Sinclair Computers

Introduction

Sinclair Research Ltd, a British company founded by Clive Sinclair, created some of the most memorable and influential microcomputers of the 80's, including the ZX80 in 1980, available for under £100, a breakthrough in price for a computer at the time in the UK. The ZX80 was followed by the ZX81 in 1981, another machine offering great value for money and selling millions of units, appealing to people of many different backgrounds. Another success was the ZX81's follow-up in 1982, the ZX Spectrum, the first of the Sinclair computers to be able to offer a colour video output while still retaining an 'affordable' price tag, and the base model was succeeded by improved versions such as the ZX Spectrum+ in 1984 and the ZX Spectrum 128 in 1985. Not all Sinclair computers sold well, with the Sinclair QL, released in 1984, failing to attract enough demand even despite its advanced features and relatively low cost. Amstrad would later release the ZX Spectrum +2 and +3, along with slight variations, having bought the Spectrum and Sinclair brand in 1986.

Read on to learn more about the various Sinclair computers discussed on this page.

Please note that unless otherwise stated the screenshots on this page were taken using an Elgato capture card using the composite video connection.

There may be multiple links to the same resource where there is a different format available or just to provide another option in case a link goes down.

Sinclair ZX81

Successor to the ZX80, the ZX81 came to market in 1981 in the UK, improving on its predecessor by reducing the ZX80's chip count from 21 to just 4, as well as a price reduction of £30, selling for £50 in kit form and £70 ready built. The computer is contained in a small, black case which contrasts greatly with the larger and mostly white, ZX80, the ZX81 being truly portable weighing only 340 grams, and measuring 167 x 175 x 40mm.

As mentioned earlier, the ZX81 uses just four chips; a Z80A running at 3.5MHz (note: slightly faster than ZX80's CPU), ULA, 8KB ROM (containing the Sinclair BASIC interpreter), and 1KB RAM (some ZX81 revisions had two RAM chips). The system RAM could officially be expanded up to 16KB but some third party expansions went beyond 16KB. The stock 1KB RAM of course made for a challenge writing software and encouraged the use of machine code to make the most efficient use of the very limited space. 

In its original form the ZX81 cannot produce sound, likely to cut down on costs by simplifying the circuitry, and the computer outputs black and white images only, again, to lower costs. Note that, for example, the much more expensive BBC Micro released in 1981, that sold for £235 to £335 depending on the model variation, produced a colour display and sound. It is possible to generate sound from the ZX81, such as through the cassette port, and colour video interfaces were available for the computer.

When viewed from the top (see below for a photo of my ZX81), the computer has a 'Sinclair' and 'ZX81' badge, the rest of the space is taken up by a 40 key membrane keyboard, which has BASIC keywords and other functions written on some keys, and above and below other keys, and some keys have graphic symbols on them.

In the following photo you can see the left side of the ZX81, please note that one of the feet is missing so the computer doesn't sit flat:

You will find a TV female RCA connector, and three 3.5mm 'audio' female connectors; EAR (connects to the earphone socket on a cassette player for loading a program), MIC (connects to the microphone socket on a cassette player for storing a program), and 9V DC for power. As you can imagine, while it may have saved a little bit of money using the same connectors where possible, I'm sure more than a few people must have accidentally plugged the power supply into the wrong connector and damaged their ZX81. For reference, the power supply connector is a male 3.5mm TS plug, the sleeve is GND, tip +V.

The RF TV connector is the only means to connect a ZX81 to a screen other than doing a composite modification, which has the advantage of better quality image and no need to tune a TV in to the computer's RF frequency. If using RF, however, the image quality may be especially bad (even for RF) since the original ZX81 computers were designed to interface with black and white TVs, causing colour TVs to have trouble displaying the images correctly. Later versions of the ZX81 should give a better image on modern TVs but either way, if you have an old B&W TV that would be best to use.

Note that the ZX81 made use of a standard household cassette player for loading and saving programs, unlike other computers of a similar time, such as the Commodore 64, which used the specialised Datasette recorder.

The only thing to be found at the rear of the computer is the male expansion edge connector:

Examples of expansions available for the ZX81 include additional RAM, Centronics printer, RS232, and joystick interfaces, 3.5" floppy drive, and high resolution graphic card.

Here is the bottom view of the ZX81:

As you can see on mine, only one of the original feet remains (top right), interestingly enough the foot that doesn't hide one of the screws keeping the case together. The previous owner glued larger feet (it certainly wasn't me who installed them) but it would appear that two of them are missing judging by two square outlines top right and bottom right. I'll have to get around to cleaning up the underside and perhaps removing the larger feet or at least installing some replacement feet to replace the missing original ones.

Emulators

While it's great to be able to use original hardware the ZX81 can be quite expensive to buy second hand and even if you do obtain a working one it can be tricky to get a stable and clear picture on a modern TV. Emulators are a type of software that recreates the ZX81 environment on modern computers, giving the cleanest imagery and ease of use while also offering the luxury of taking screenshots, video recordings, software development and debugging in a much more convenient form.

You will find a list of ZX81 emulators by following this link:

https://emulation.gametechwiki.com/index.php/Sinclair_ZX81_emulators

The various emulators run on mainly Windows, some on other operating systems too, and most of them emulate a number of Sinclair computers in addition to a ZX81.

For my first try of a ZX81 emulator I looked for recommendations online and decided to try the free EightyOne Sinclair Emulator, which emulates a range of Sinclair computers including the ZX80, ZX81, various Spectrum models, Timex models, and less well known variants including Sinclair clones. The emulator has accurate timing emulation to match that of a real Sinclair machine, support for a large number of add-on interfaces, and detailed debugging abilities. Although the emulator is no longer actively developed by the original author, the source code being available allowed for development to be continued.

EightyOne can be downloaded from:

https://sourceforge.net/projects/eightyone-sinclair-emulator/

There are downloads for both the source code and executable through the above link. 

I download V1.37 (EightyOne V1.37.zip), released 1/5/23. Starting the emulator is straightforward, just unzip the downloaded file and run the executable EightyOne.exe.

Here is a screenshot showing the EightyOne emulator once it fully starts (a splash screen is displayed while it loads):

The software defaults to emulating a 16K ZX81 as is made clear at the bottom of the window.

There are various menus for loading and saving tape images, graphics options, reset and other control, configuration, tools, and help. The next image shows the selection of hardware and options, reached through the Options->Hardware... menu:

Through the menu I switched to Spectrum +2 as seen below:

I switched  back to ZX81 mode and started to enter a simple loop program in BASIC:

Since this emulator is running on a PC we don't have the luxury of a keyboard with the keywords and symbols for a ZX81 written on it but you can call up a keyboard map from the Help menu, by going to Help->Keyboard Map:

The keyboard map reflects the hardware being emulated but it's a shame it's not interactive.

In the following window capture you can see the results of running the program I entered but note that I also enabled scanlines (Options->TV Emulation... check 'Artefacts Enabled') to look a bit more like it's running on a CRT:

A very handy feature is that you can view and save a BASIC listing to your computer in text form rather than saving as a virtual tape image, for example. The BASIC listing tool is accessed using Tools->BASIC Listing... Click the Save button for the option to save the BASIC listing to your computer.

Unfortunately there doesn't appear to be a way to copy of paste BASIC programs to/from the emulator, or load from a file.

Another helpful tool, useful for delving into the inner workings of a retro computer, is the debug window, which is called up through Tools->Debug Window... In the image that follows you will see that I have also clicked the Memory button, resulting in the Memory window coming up:

There are a number of tape images included with the emulator and others can be download. To load a tape go to File->Open Tape... choose the file and click the Open button. The process of loading the tape is automatic, making it much easier to work with tape software. You can find the included tape images in the Examples\Tapes\ZX81 folder; the Demo.t81 file has a number of games that can be played from its main menu. The next two screenshots show gameplay from 3D Monster Maze and Forty Niner, respectively:

I feel that EightyOne is a very versatile emulator that is easy to use while providing many modes and options for any Sinclair fan or for someone who wants to experience a ZX81 or Spectrum but doesn't have the original hardware.

Technical

Ram packs containing 16K or higher memory disable the ZX81's internal RAM.

Software

As well as more serious applications, the ZX81 was known for its quirky games, five of which you can see in the video that follows:

Troubleshooting

Teardown

To open up, remove the four screws from the underside, three of them are located under three of the rubber feet: when looking down with the expansion port end facing away from you, the feet that need removing are the top-left, bottom-left, and bottom-right. Once all screws have been take out you can lift the bottom piece of the case away, giving you access to the PCB:

Since my ZX81 is issue one, it has written on the PCB 'Sinclair issue one 1980'. Notice that there is a large piece of metal (which has gone 'bad') that touches the voltage regulator's heatsink just visible underneath; I don't know if it was added later perhaps to help with heat dissipation.

To remove the PCB, take out the two screws holding it down and then carefully lift up the PCB but be aware of the two keyboard flat cables which commonly end up broken - these are called ‘tails’ in the ZX81 assembly instructions. Any tear or sign that either cable is about to break, the keyboard will need replacing.

The top side of the PCB has written 'Sinclair ZX81' and 'Issue one.'

The PCB in particular features an RF modulator by Astec type UM1233, cassette and power connectors, 7805 voltage regulator with heatsink, expansion edge connector, and two keyboard connectors. The ICs are:

8120 ULA

D2364C (socketed) 8KB ROM

Z80A (socketed) 8-bit CPU

MK4118 1KB SRAM

Note: the chips in your ZX81 may have different part numbers.

According to Sinclair the board can accommodate either two SRAM chips (x2 2114, 1K x 4, 18-pin), single SRAM chip (4118, 1K x 8, 24-pin), or single DRAM chip (4816, 2K x 8, 28-pin, pseudo-static RAM). The flexibility was likely to allow for whatever RAM chips were at hand to be used and possibly other, compatible chips will also work provided they meet the minimum timing. I couldn't find a definite answer online but looking at the RAM chip in my ZX81 - MK4118-4 - it has access time of 250ns, so RAM chips should be at least that fast to work in a ZX81.

Please read on for specific repair information.

Bad power supply

WARNING: working with power supplies can be very dangerous; do not open up or attempt any repairs unless you know what you are doing and exercise caution.

I had a ZX81 power supply, model UK 1400, rated for 9V @ 1.4A, but when I measured the output with my multimeter I was getting a reading of <1VDC, so it had obviously failed. To open up the power supply you need to remove the 3 screws from the underside. It's a very simple linear supply consisting of a large transformer, 4 diodes, and a capacitor. On the underside of the PCB it says 'DPL 83’3'.

I measured 3.7VAC at the transformer output and also noticed a burning smell, likely because of one or more of the diodes, which were getting very hot. Testing the diodes (with the power off, of course) revealed that they tested fine but upon closer inspection I could see that one of the diode legs had snapped and one of the pads to another diode had lifted. I removed the diodes but before replacing them I tested the transformer output again and now I got 9.9VAC, a much more healthy result. The 4 diodes are of type 1N4002 and I changed them with 1N4007, as I had them at hand, but are actually rated better than 1N4002, and I used a wire to connect 2 of the diodes due to the lifted pad. I also replaced the capacitor, rated 4700uF/16V, and now the power supply was giving out 12.3VDC, which is more like what we would expect from a 9V unregulated power supply.

If you want to make your own power supply then it needs to output DC between 8 and 12V (8V is better to lower heat dissipation of the 7805) but does not need to be regulated, just smoothed well. Sinclair recommended the power supply needs to be able to supply a minimum of 600mA, or 1.2A if the printer is powered off the same supply. Powering my ZX81 off my bench power supply it drew 360mA @ 9VDC but that of course will go up if I attach a memory expansion or other device to the computer's expansion port.

ULA dead

The ULA chip tends to fail over time due to heat issues, if you have a ZX81 with a working ULA it's advised to install a suitable heatsink on it so that it keeps working. If the ULA has failed, other than replacing with a known working one from another source, there are modern drop-in replacements, or you can make your own, which this site has information on:

https://oldcomputer.info/8bit/zx81/ULA/ula.htm

Sinclair ZX Spectrum 16K/48K

Successor to the ZX81, the ZX Spectrum came to market in 1982 in the UK, with two main versions available; the 16KB RAM model for £125 (upgradable to 48KB using an internal upgrade or externally with an aftermarket expansion), and 48KB model for £175. The name 'Spectrum' was chosen because of its ability to produce a colour display (unlike the machine's predecessors), which was fitting since the machine proved to be very popular for video games, with some notable games including Jet Set Willy, Dizzy, and Manic Miner. In just a year the Spectrum sold 1 million even though it had initial manufacturing problems and would go on to sell 5 million in total, becoming one of the UK's best selling computers.

Powering the Spectrum is a Z80A clocked at 3.5MHz, and a 16KB ROM contains the BASIC interpreter, there is basic sound generation through the internal speaker, and the computer outputs a video signal of 256 x 192, and can produce 15 colours. Unfortunately, peripheral support was lacking in the Spectrum's on-board ROM, meaning that the periperhals themeselves had to contain a ROM for funtionality. Another issue was that, unlike other computers which required BASIC keywords to be entered in full (or optionally through shortcuts), the Spectrum required single key presses for entering keywords, which had the advantage of faster program entry once mastered but caused a steep learning curve.

Even though the Spectrum is small it is quite heavy, is mainly black with rectangular grey rubber keys (blue-grey on issue 2 and later versions), and has rainbow stripes across one corner, helping to grab attention. There is an odd placement of some of the keys by today's standards; break/space, for example, and there are colour, command and functions written between keys in various colours.

At the back of the computer is a 9VDC barrel jack for power, expansion edge connector (not labelled), MIC and EAR for cassette loading and saving, and RF TV out. Oddly, there looks to be a faint outline between the ear and TV connections. On the underside it says: Sinclair ZX Spectrum personal computer Use only approved AC adaptor Patent pending Made in UK. 16K version. There are small dots arranged in a curve near the bottom left for the internal speaker.

I couldn’t find an easy way to determine from software how much RAM the system has (in case you don't know whether you have the 16K or 48K model) but it can be done with the following BASIC:

Print peek 23733

The command gives the most significant byte of the last byte of physical RAM, this is known as system variable P-RAMT (one byte of a 16-bit address) and is set by a ROM routine which stores the address of the last working byte of upper RAM. Supposedly, if the result is 128 it’s 16K, 255 for 48K, and 127 if it’s a ‘48K’ machine sold as a 16K machine due to faulty upper RAM. But if there’s faulty RAM it’s possible to get other values.

This site has details for upgrading a 16K machine to 48K:

https://spectrumforeveryone.com/technical/upgrading-a-16k-spectrum-to-48k/

Since my Spectrum already has upper RAM chips soldered (TMS4532) yet it’s a 16K machine it looks to be an example of a 48K machine with failed upper RAM sold as a 16K computer.

To take apart the Spectrum there are 5 screws that need to be removed; be careful of the 2 keyboard flat cables that need carefully removing before the two parts of the computer shell can be separated. By opening up my Spectrum I found that it has a Issue 3B 1983 PCB, a very common version. For information about the different PCB versions please see:

https://spectrumforeveryone.com/technical/zx-spectrum-models/

The Spectrum power supplies, with the exception of the +3, are generally reliable but it's always best to check that the supply is not dead and if not, that the voltage is correct before using. When testing the power supply while not connected to a Spectrum, the voltage will be higher than 9VDC, since it’s an unregulated supply; the voltage will drop to 9V when the maximum current is being drawn. For e.g., two of my +2 power supplies that I tested (not connected to the computer) read as 11.6V, which is to be expected.

Tips


Upgrades


Composite Mod for the 48K range

https://spectrumforeveryone.com/technical/composite-mod-for-the-48k-range/


Upgrading a 16K Spectrum to 48K

https://spectrumforeveryone.com/technical/upgrading-a-16k-spectrum-to-48k/

ZX Spectrum 48K - How to replace the ROM with an EPROM

Sinclair ZX Spectrum +2

Please note that the majority of screenshots in the section were taken using an Elgato capture card with an upscaler using the computer's RGB connection.

The Sinclair ZX Spectrum +2 was Amstrad's first Spectrum since they had acquired the Spectrum name and range in '86 and was the first Sinclair to be manufactured outside UK, that is, in Taiwan. The Spectrum +2 is essentially the same as the previously available ZX Spectrum 128 but has some software compatibility issues and the boot menu lacks the Spectrum 128's "Tape Test" option.

Released in '87 and priced at £200, the Spectrum +2 runs on a Z80A CPU @ 3.5MHz, has 32KB ROM (16K for 128K mode, 16K for 48K mode), and 128KB RAM. Unlike many of the other computers of the time the Spectrum was at disadvantage because it did not have a dedicated display chip and thus had only one display mode, which provided 32 x 24 characters giving a resolution of 256 x 192 pixels. However, in BASIC the bottom 2 lines of text are used by the BASIC interpreter to communicate with the user. There are only 15 colours in total to choose from for a character since of the available 8 colours there are normal and bright versions (black looks the same in both variations).

The Spectrum +2 has a 58 key keyboard with the same layout as the Spectrum+, although with spring loaded keys, but with the most difficult to get used to layout of keys from a modern PC perspective (why on earth are the double quotes at the bottom left of the keyboard?!). As to be expected the Spectrum +2 boasts colour graphics, and has 3 sound channels with 7 octaves each.

Take a look at the photo that follows:

You can see the Spectrum +2's resemblance to a number of Amstrad computers such as the Amstrad CPC 464 mainly because of the built-in cassette recorder which is known as a Datacorder.

For a look at the various ports at the back of the Spectrum +2 see this photo:

From the left: 9VDC power in, expansion I/O, RS232/MIDI (keyboards, printers, musical devices but as MIDI out only), keypad (for connecting a numeric keypad - released only in Spain), RGB (RGB and composite), TV (RF), sound (mono). 

Note that the later revisions - +2A and +2B - output 12V on the composite pin, which could damage a connected TV/monitor. This document goes into detail about various audio and video options for a number of different Spectrums, including the +2:

https://mts.speccy.cz/doc/128_rgb.pdf

Please also see the Tips section for my own experience of making up an RGB SCART cable.

On the left side of the computer are 2 'Atari' joystick ports and the reset button. The joystick ports don't use the 'Atari' pinout since Amstrad wanted you to buy their joysticks; this is why near the joystick ports it warns to use 'SJS1' type joysticks. Alternatively, an adapter allows the use of Atari compatible joysticks or you can rewire the joystick ports internally, as shown on this site:

https://spectrumforeveryone.com/technical/rewiring-your-23-joystick-ports-to-atari-standard/


The built-in joystick ports map to keyboard keys, and adding an additional joystick port via an expansion add-on means you can have three joysticks (not that any software would normally be able to take advantage of it though).


See the Tips section for testing joysticks.

For information on connecting the Spectrum to a PC for loading/saving files please see:

http://www.fruitcake.plus.com/Sinclair/Interface2/Cartridges/Interface2_RC_New_RS232.htm

Standard composite video signal should be available on pin 1 of RGB port provided link LK4 on the motherboard is present. The RGB signals are TTL and can not be connected to a TV via SCART without a circuit that makes use of the bright and RGB signals to get full range of colours. See following link for more info:

http://www.fruitcake.plus.com/Sinclair/Spectrum128/SCARTCable/Spectrum128SCARTCablePlus2.htm

As was common with Spectrum computers the +2 has no power switch; as soon as you plug in the power supply the computer turns on.

When the Spectrum +2 boots or reset is pressed (see image below) it displays a menu allowing you to choose between Tape loader, 128 BASIC (Spectrum 128 software mode), calculator, and 48 BASIC (Spectrum 48 software mode). Other than providing backward compatibility, some notable differences between 48K BASIC and 128K BASIC is that 128K BASIC requires keywords to be typed in full and it has a full screen editor.

Having chosen '128 BASIC' I've wrote a simple BASIC program (see screenshot below); can you guess what the output will be when run?

You will notice that the computer makes a sound every time a key's pressed.

A nice feature of Spectrum 128 BASIC is that each line is checked when entered and if typed in correctly, the computer will beep and the line will be added to your program, unlike other BASIC implementations in which errors in program syntax are only highlighted when the program is run. If a program line has error(s), the computer will make a different sound and will point out the error while not allowing the line to be added to your program until it's corrected. In the next screenshot you can see that I have purposely spelled 'next' wrong and the computer has pointed it out:

The arrow keys can be used to move to the part of a listing you want to alter and edits can be made in place as needed (BASIC on other computers made editing much more difficult).

Here's the output of running the program when entered correctly:

Notice that toward the bottom of the screen the computer reports that program execution was successful and it ended on line 30. Press a key to return to your program listing.

In a moment we'll be looking at a simple BASIC program to show off the computer's colours but first let's look at the options menu which can be brought up by pressing the edit key while in 128 or 48 BASIC:

The option '128 BASIC' just returns you to BASIC, 'Renumber' renumbers a BASIC program, 'Screen' puts you at the bottom of the screen so that you can run commands or enter program lines without disturbing whatever is already on the screen, 'Print' outputs a program to an attached printer, and 'Exit' returns you to the boot menu.

The Spectrum +2 can generate 16 colours but two of the colours are identical blacks so really it's 15. Here is a simple program which introduces a few useful BASIC keywords and shows the range of colours available:

5 INK 9

10 FOR b=0 TO 1

20 BRIGHT b

30 FOR c=0 TO 7

40 PAPER c

50 PRINT "colour ";c;" bright ";b

60 NEXT c

70 NEXT b

Starting on line 5, The INK keyword is used to set the text colour but the value 9 has a special effect - instead of actually setting the text colour, it ensures that the text contrasts with the page (background) colour, which is very useful so we don't have to change the text colour to avoid colour clash. The text colour will remain in its default, which is black.

Line 10 sets up a loop using variable b to start on the lowest brightness (0) and we actually set the brightness level on line 20 using the BRIGHT keyword.

On line 30 we start a new loop, this time using variable c to loop through each of the 8 colours (0 to 7) and the background is set to c on line 40 using the PAPER command.

Line 50 is where we output text identifying the current colour and brightness values in the colours that are currently being used.

On line 60 we go to the next value of c as to go through each colour and once we've done that we'll end up at line 70 where we'll move on to the last brightness value (1) and then display the coloured text again. When the program finishes there will be 16 lines of coloured text as follows:

Also available from the boot screen is '48 BASIC', of which you can see me putting together a simple program in the following image - this should be familiar with anyone who has used a Spectrum 16/48K machine:

As with many computers of the time, the Spectrum  +2 uses cassette tapes for data storage, which was far from idle but at the time of the Spectrum it was one of the cheapest methods. Anyone who has loaded games from cassette will be familiar with a loading screen such as the following (taken from Tranz Am):

It was common practice with microcomputers to rapidly change the colour of the border and produce a sound to show that the program was being loaded from cassette as it was a lengthy process. Some games, such as Tranz Am seen above, would display a splash screen some way through the loading process almost as a reward for waiting so long.

As well as loading software from cassette using the traditional method you can also take advantage of the Spectrum  +2's built-in Tape Loader, accessible from the boot screen:

Peripherals

A numeric keypad was released for the ZX Spectrum 128 in 1986 to the Spanish market (apparently as part of a bundle), it appears no version was available outside Spain even though the UK ZX Spectrum +2 manual mentions it. You can view the keypad at this site (which oddly mentions a UK price):

https://spectrumcomputing.co.uk/entry/1000503

Even if you did obtain the keypad, likely it won't work with a UK Spectrum 128, learn more at this site for the details including the fix:

https://spectrumforeveryone.com/technical/fixing-keypad-issues-on-an-issue-6k-128k-toastrack/

Tips

BASIC

LET must be used when assigning a value to a variable.

NEXT requires the variable even if there is only one active loop in the program.

GO TO can be entered as either 'GO TO' or 'GOTO' but will get corrected in the program listing.

Joysticks

The Spectrum +2 doesn't use Atari compatible joysticks but as well as joysticks designed especially for the Spectrum +2 (such as Amstrad's ones) a number of third party joysticks - such as the Cheetah 125+ supports both the Amstrad and Atari standards by providing two plugs; grey for Amstrad and black for Atari. Whatever compatible joystick(s) you are using you can test them using this simple BASIC program:

10 LET J$=INKEY$

20 PRINT AT 0,0;J$

30 GO TO 10

A value will be displayed corresponding to the direction/fire button that was pressed for either joystick port, as follows:

For port 1:

6=left, 7=right, 8=down, 9=up, 0=fire

For port 2:

1=left, 2=right, 3=down, 4=up, 5=fire

Although the test program demonstrates a means to read the joystick it's actually even easier to test than using a program, just press on either joystick or fire button and the number value will be displayed as if entered from the keyboard (and will auto repeat if held down, just like a keyboard key). This works because the joystick port signals are wired to the number keyboard keys and will work in both 128 and 48 BASIC, take note. This approach has the advantage that software not written with joysticks in mind will actually support a joystick, provided they use number keys (or can be configured to do so).

Power supply

The original UK power supply outputs 2.1A at 9VDC, when running off my bench power supply I found that my Spectrum +2 had a current draw of 930mA at 9V, suggesting that a 1A 9VDC power supply could be used provided the computer was being used without any peripherals attached.

RGB SCART cable

It's possible to connect a Spectrum +2 to an RGB enabled SCART socket of a TV, which will give the best quality image, using either a readily available cable or you can make one yourself, which will be described here. It's important to understand, however, that even if you buy a cable that's supposedly suitable, you may still have to do modifications to the computer, which is what I discovered through my own experience and researching online. Note that my Spectrum +2 is a UK model, issue 3, PCB type Z70500, you may have to make different changes for your particular Spectrum so exercise caution before making any modifications.

The Spectrum +2 RGB connector outputs R, G, B, and brightness signals on pins 7, 6, 8, and 3, which initially I was under the impression I would have to combine together externally to get the full range of colours, however, it turns out that the Spectrum +2 already combines the brightness signal with RGB internally (provided that resistors R12-R14 and diodes D9-D11 have been fitted) even though it also outputs the brightness signal but we'll get back to that in a moment. To drive RGB SCART we need to connect R, G, and B to the corresponding signals on a SCART cable via 150R resistors, which I found to give the best contrast between the colours even if the brightness levels aren't exactly right - feel free to try other resistor values but resistors must be included to get the full range of colours.

Most TVs and upscalers require a blanking voltage to tell it that it is to use RGB instead of composite and we can get a suitable voltage from the Spectrum +2 by cutting LK1 on the motherboard (behind the RGB socket) and soldering LK3, which will cause +12V to be output on pin 5 of the RGB socket instead of vertical sync. However, on my Spectrum +2 there was no such voltage on pin 5 and looking online supposedly there is a resistor that's too high value that needs to be swapped but there was no such resistor on mine. So I soldered a 560R resistor between LK3 and a nearby 12V rail on the solder side of the board, which gives 1.6V blanking voltage.

The other thing we have to do is connect composite video (pin 1 on the RGB conncetor) to composite in on the SCART cable, which not only provides sync to the TV for RGB but it also means that the TV (or upscaler) can use composite should RGB not be available (e.g., the TV doesn't support it). Handily, we can also route audio to pin 3 on the RGB socket (and still have it available through the audio socket) by cutting LK7 (near the AY-3-8912A chip) and soldering LK8, the audio signal can then be fed to the L and R audio in channels of the SCART socket.

Although the image through RGB is much cleaner than composite and RF, I noticed faint 'jail bars' and jittering, something that possibly can be cleaned up. I haven't yet investigated further but this site explains how to fix the issue for various Spectrums:

https://spectrumforeveryone.com/technical/fixing-vertical-jailbars-48k-128k-spectrum/

Troubleshooting

General

The Spectrum +2 has a built-in colour and sound test which can be accessed by holding down the break key and while keeping it held, press and release the reset button. Alternatively, you can hold break and power on (plug in the power supply). A number of coloured bands will be displayed with '1986' written in various colours, and a tone will be played. Please see the image that follows:

Poor composite video

Although the RF connection worked on my +2 it wouldn't display a clear image through composite (there is a lot of distortion) even though you would expect composite to give a better image. Looking inside I found that the motherboard is issue 3 which is known to have 3 transistors (all 2N3904) installed the wrong way. While it's supposedly fine to leave 2 of the transistors as they are, TR4 (next to the modulator - see photo below) needs to be desoldered and checked; if the transistor is fine then solder it back in but the other way round, if it's bad replace it with a working transistor and install it the opposite way to the failed transistor. 

Even after changing the transistor, and C6 also for good measure, I was still getting poor quality over the composite connection. Looking at a guide I found at:

https://www.benophetinternet.nl/hobby/vanmezelf/ZX%20Spectrum%20128K%20video%20fixes%20and%20video%20cables.pdf

I followed the mod to reroute the specified capacitor and now the composite signal is a lot cleaner.

Expansions for ZX Spectrum

RamPrint with RamWrite

RamPrint with RamWrite is an expansion device for the ZX Spectrum 48K, Plus and 128K, released by Ram electronics Ltd. (designed & manufactured in the UK) in 1986 for £34.95 and Datel also, for £34.99. It incorporates a Centronics printer interface, Kempston compatible joystick port(supporting Atari type joysticks), as well as RamWrite word processor software on board. As there is a joystick interface built in there is no need to swap out RamPrint when gaming and the having the word processor part of the expansion device means it can be instantly called up when needed.

You can see RamPrint in the following photo:

Note the RAM logo bottom left of the device, the RAMPRINT WITH RAMWRITE label (unfortunately peeling off) bottom right, and the Centronics cable and joystick port at the back.

In the next image you can see the expansion connector that plugs into the appopriate port on the Spectrum:

Note that on the right side of the RamPrint there is a missing plastic support ring that was intended to go around the Spectrum's power socket (sadly it was broken off when I bought my RamPrint).

The bottom side of the RamPrint isn't too interesting, there are four screws that need to be removed to take apart the device, which we'll look at shortly:

My ZX Spectrum is 16K, which isn't supported by RamPrint, but I do also have a +2, RamPrint however, does cover up the MIDI port, which isn't a big deal, more of an issue is that RamPrint doesn't work in 128 mode - there is a mention online that it needs initialising but no details how to do that. At the time of trying out RamPrint I found no copy of the manual online but a I did find a few reviews, reproduced from magazines from what I can tell, for example, RamPrint was covered in issue 58 (Jan '87) of Spectrum user. Here are some links as they do have some useful information about RamPrint:

https://www.crashonline.org.uk/35/ramprint.htm

https://spectrumcomputing.co.uk/zxsr.php?id=1000327

Fortunately RamPrint does work in 48 mode on the +2 but is tricky to get working because of the unusual means of entering BASIC keywords. To start the word processor use:

LPRINT "©word"

Yes, that is the copyright symbol and not just '(c)'. You will instantly be greeted with the start screen:

Press the enter key and the version number will disappear and you will then get a flashing cursor in the command window. If you press E and enter you will move to edit mode but before you can type you will be prompted for a name. Type in a name and press enter and the cursor will appear at the top of the screen - the text window - where you can type your document, an area of 32 x 21 characters. You can see an example of some test text I entered - note the carriage return symbols:

The cursor keys let you move around the text and make edits, typing will overwrite and the computer's edit button toggles between insert/overwrite, as indicated in the status area. Break is used to switch back to the command window.

D is the display command (entered in the command window) and will show you how your test will look on printer.:

'Page' will flash; press enter to move through each page of your document or press break to return to the command window.

This was a brief look at using RamWrite - please see the previously linked sites to learn more about using RamWrite. I didn't have a suitable printer to test out printing using RamPrint but I was able to test the joystick port. If you want to test the joystick port you will need an Atari compatible joystick and you can use this simple BASIC program which will indicate the direction/fire button that was pressed (only one button at a time):

10 LET J=IN 31

20 IF J=1 THEN PRINT AT 0,0;"RIGHT"

30 IF J=2 THEN PRINT AT 0,0;"LEFT "

40 IF J=4 THEN PRINT AT 0,0;"DOWN "

50 IF J=8 THEN PRINT AT 0,0;"UP   "

60 IF J=16 THEN PRINT AT 0,0;"FIRE "

70 GO TO 10

I tested using a Cheetah 125+ joystick using its black connector (the Atari compatible plug).

To take apart RamPrint remove the four screws from the underside and then lift the bottom piece off, note that the top piece is actually composed of 2 pieces. On my RamPrint it has written on the PCB 'SIDE 1 ISS. 3', so this is a later version.

Lifting out the PCB reveals the other side which, on my version, has '8636' printed on it - possibly the date -'SIDE 2 ISS.3', 'PRINTER I/F', 'SPECTRUM', and 'SP48P'.

Of particular interest is the ICs, which are:

74LS374 octal D-Type edge triggered flip-flops with 3-State outputs

74LS366 hex bus driver with 3-state outputs

74LS125 quadruple bus buffers with 3-state outputs

74LS139 dual 2-line to 4-line decoders/demultiplexer

74LS74 x2 Dual D-type flip-flop

74LS32 x2 Quad 2-input OR gate

P2764A-2 x2 (socketed) 8K x 8 ROM

Presumably two 8KB ROMs were used as a single 16KB ROM would have been more expensive. I have made copies of the ROMs that you can download for research purposes or if you need to burn new ROMs, they are available at the bottom of the page. 'Ramprint with Ramwrite ROM 1.bin' is the ROM closest to the joystick port, 'Ramprint with Ramwrite ROM 2.bin' is the ROM near the expansion connector.

As I had my Spectrum +2 running off my bench power supply I was able to observe that RamPrint draws about 80mA.

Currah µSpeech (Microspeech)

The µSpeech (a.k.a. as Microspeech) from Currah Computer Components Ltd was released in 1983 for £29.95 and gave the Spectrum the ability to speak. You may like to watch a video I did on the Microspeech:

The original Microspeech package consisted of a small box containing the µSpeech cartridge, Game & demo cassette, and programming manual. The box states 'SPEECH & SOUND From your T.V. set FOR SINCLAIR ZX SPECTRUM'. Here some highlights from the back of the box:

Speech and Spectrum Sound from your T.V.

Infinite vocabulary.

All speech handled by custom gate handled by custom gate array and integral ROM based software.

Full key voicing on power up. (Disabled by LET keys = 0) (Re-enabled by LET keys = 1)

Generate any speech string using S$, eg: LET S$="HE(LL) (OO)" will say "hello"

Syntax check on your speech strings to indicate where errors occur.

Intonation to add character.

Hi-fi or tape recorder output.

Compatible with Sinclair Microdrive.

The back of the box also has an illustration showing the cartridge plugged into a Spectrum's expansion port as well as the EAR and TV ports, and the cartridge connected to a TV via its aerial lead.

The speech may seem very primitive by today's standards and although some words can be difficult to understand, you have to appreciate for the time that Microspeech was quite groundbreaking. What is annoying, however, is that when keyvoice is on (speaking out the keys you press) you also get the usual key click in addition to the speech. However, you can just connect the audio plug from the Microspeech cartridge into a speaker and get just the speech, and that also gets round the issue of having a modded Spectrum that outputs composite, which is not compatible with the Microspeech without itself being modded to accept composite input.

As well as controlling Microspeech from your own programs the cartridge is also supported by some games to add speech, with an example of a game with optional support for Microspeech being Steve Davis Snooker published by CDS Microsystems of which you can view a video of the game with the speech enabled but be warned there are some far from pleasant sound effects:

Another example is Blade Alley published by PSS and you can watch some gameplay of it below:

In the case of the Spectrum game Booty, Microspeech appears to unlock a secret sub game but may actually be due to the Microspeech corrupting memory used by the game, triggering the sub game. Some games - such as RoboCop - won't even work while Microspeech is connected.

If you do not have access to the original hardware, the EightyOne Sinclair emulator (see the Emulators section on this page) emulates the Microspeech add-on. After launching EightyOne select Options->Hardware..., pick a Spectrum machine, check 'Currah μSpeech', and then click the OK button. The machine will then launch with Microspeech activated. Oddly, you can even use Microspeech with an emulated Spectrum +2 even though on a real Spectrum +2 the Microspeech doesn't work (or at least, it wouldn't work on my +2).

To learn further about Microspeech please see the programming manual at:

https://k1.spdns.de/Vintage/Sinclair/82/Peripherals/Currah%20uSpeech/Manual.pdf

Sinclair QL

The Sinclair QL or Quantum Leap was a less successful computer from Sinclair Research from 1984 that can be thought of as a higher end version of the Spectrum that was aimed at serious home users and professionals including businesses, contrasting with the Spectrum which had been seen more as a 'games' computer. The QL sold for £399 in UK, also available in Europe and America, and did away with the Spectrum's 8-bit Z80 CPU running at 3.5MHz, using instead an 8/32-bit 68008 clocked at 7.5MHz. The machine features 128KB RAM (expandable up to 896KB), two  built-in microdrives (each microdrive cartridge stores 100KB), and unlike the Spectrum it can output composite and RGB as standard, providing for much clearer images. The graphics is handled by a ZX8301 ULA and an Intel 8049 drives the built-in speaker as well as dealing with the keyboard, joystick ports and RS-232 ports.

The QL's keyboard has 63 'standard' keys and 5 function keys.

While the QL doesn't suffer from 'colour clash' as seen on the Spectrum, the QL only has 8 colours compared to the Spectrum's 16 (15 really as there are two blacks), and this may have been down to the QL not intended to be a games machine although of course business software, for example, can still make good use of a decent colour range. According to David Karlin, chief designer of the QL, there wasn't an available pin to increase the total number of colours. While talking about the QL's graphical capabilities, the machine only has only bitmap video modes, which has the disadvantage that text display is slow compared to a computer with character video modes, such as the Spectrum.

It's interesting that a form of BASIC is built into the QL considering it was designed to be a 'serious' computer, support for CP/M - which would have allowed for loading of  BASIC amongst other software - would have been more appropriate.

The QL originally was packaged with the user guide, power supply, QL software pack by Psion containing QL Abacus (spreadsheet), QL Archive (database), QL Easel (business graphic), QL Quill (word processor), 3 plastic feet (to tilt the QL forward), aerial lead and network lead.

At boot the computer will prompt you to press F1 for monitor mode (high resolution of 512 x 256) or F2 for TV mode (low resolution 256 x 256). After pressing F1 or F2 the QL will try to load software from a cartridge in microdrive 1 (the drive LED will be illuminated) and if unsuccessful you will be dropped into BASIC. 

I had never used microdrive cartridges until getting a QL, along with the originally bundled software and a number of blank cartridges (which the seller had applied new felt to to ensure their continued operation). Unlike other computers which prevent computer use while files are being accessed, the microdrive motor may continue running even after control has returned to the user, allowing you to continue giving commands while the microdrive finishes its task

Although I would have preferred the QL to have a built-in floppy drive, which would have allowed transferring of files from PC to be more straightforward I actually think the microdrive cartridges are quite neat. They are small, light, and while not that fast even for the time, floppy disks are quite unreliable and slow so I could see Sinclair's reasoning for use microdrives. 

An unboxing of a QL can be viewed in the following video:

The RF socket can be used to connect a QL to a TV but that gives the worse looking image where composite through the RGB socket using an appropriate lead is the next best option and is suitable for a TV or monitor with composite input. For the very best image quality RGB signals can (not surprisingly) be obtained though the RGB socket which can be connected to a TV with a SCART lead or a monitor with RGB input. Whichever option you use you may find that some of the screen is missing (likely the left side), especially in high resolution mode, as the QL produces a non-standard video signal in monitor mode. Using a modern TV or monitor doesn't help although you may even have problems when using a CRT TV. I found that although my TV (LG plasma) cut off the left side of the image (and oddly added grey vertical bars both sides) my SCART upscaler showed a more complete image, just cutting off the very top. Keeping with Sinclair tradition, sound is not passed through to a connected TV and is only available through the internal speaker.

For the images in this section I used a video lead I made up which carries both colour composite video and RGB, conncected to an RGB to HDMI upscaler and an Elgato capture card; RGB can be selected by providing the blanking voltage to the SCART socket. So as to show the difference in quality between composite and RGB I will show a couple of screenshots taken using composite video but the majority will be using RGB. Even though RGB looks much better than composite as to be expected, it doesn't look as good as viewing directly on a TV without the upscaler and capture card, the TV showing brighter colours. Additionally, note that the capture card adds black sections to the images to form an HD picture which results in an off-centre image.

There is no power switch on the QL and so the computer boots as soon as you plug in the power, which results in a few seconds in which a garbled colour screen appears (see image below) - the user guide states that at this point the QL is testing its memory.

Note: the above image was taken using RGB.

You are then given two options, as seen in the following screenshot:

Note: the above screen capture was done using composite.

Press F1 for monitor mode which is the high resolution mode designed for monitors and may not display well on a TV, unlike TV mode which is accessed using F2, and puts the QL into low resolution mode with a different window arrangement.

For comparison here is the same screen but taken using RGB, resulting in a clear and more vibrant image:

The remaining screenshots in this section were taken in RGB mode.

After pressing F1 or F2 the QL will attempt to load a program from a cartridge in microdrive 1 and failing that drop you into SuperBASIC. The next screen shows the window arrangement for TV mode (F2) in which BASIC commands are entered at the bottom of the screen and the BASIC listing appears at the top of the screen as well as output from a program, which in this case is the available 8 colours (I didn't bother to change the paper colour for red so consequently the red text appears invisible).

As mentioned, the colours look better on a TV than the captured card shows.

BASIC commands can be entered in upper or lower case but always appear in upper in a BASIC listing. Note that if you have caps lock on, shifting a key doesn't result in a lower case letter like a modern computer does.

For reference, here is the SuperBASIC program I used to demonstrate the available colours:

10 CLS
20 FOR c=0 TO 7
30 INK c
40 PRINT "colour ",c
50 NEXT c

For reference here is a list of colours available in low resolution mode for use with the various colour commands including INK:

0 black
1 blue
2 red
3 magenta
4 green
5 cyan
6 yellow
7 white

Even though I previously selected TV mode I can use the command MODE 4 to switch to high resolution mode and four colours, which gives us the opportunity to run the BASIC program again and see a different result:

Because there are only four colours in high resolution mode, two values represent each colour (0 and 1 result in black, for example), as listed below:

0, 1 black
2, 3 red
4, 5 green
6, 7 white

You can use MODE 8 to go back to low resolution mode with eight colours.

If instead I had selected F1 at boot to put the computer into monitor mode there will be a different window arrangement, which can be seen in the next image, which shows a simple program being run:

Notice the slight jail bars on the grey (white on a TV) background and the stipples (alternating pattern acting as a border) missing from the right side, likely due to my capture card.

In monitor mode commands that are entered appear at the bottom of the screen, the BASIC program appears in the large section on the left and the results from the program appear on the right.

I also wrote a program to generate 10 circles of random size and colour, which I ran several times in low resolution mode, which you can see below:

It's impressive how fast drawing takes place considering other computers of the time, an advantage of the powerful processor.

This is the program:

10 RANDOMISE:PAPER 0:CLS
20 r=25:mX=170:mY=100:lR=5
30 FOR s=1 TO 10
40 INK RND(1 TO 7)
50 CIRCLE RND(r TO mX-r),RND(r to mY-r),RND(lR TO r)
60 NEXT s

As the program is a bit more complicated I'll explain how it works. On line 10 RANDOMISE initialises the random routine so we get different results each time, PAPER 0 sets the background colour to black and CLS clears the screen. On line 20 we set the maximum radius*, r, to 25, the maximum X position, mX to 170, the maximum Y position, mY, to 100, and the lowest radius value, lR, to 5. Although SuperBASIC supports long variable names I kept them short to save on typing.

*I realise now I should have named r as mR to be consistent but it was a program I quickly put together.

At line 30 we set up a FOR loop to generate 10 circles and on line 40 we set the drawing colour to a random value using RND() to select a colour other than black (a value of 0 is black). Interestingly, INK actually accepts a value from 0 to 255 as it uses the binary combination of bits to select the resulting colour.

On line 50 we draw a circle, first specifying a random X position from the maximum radius, r, to the maximum X position less the maximum radius, to ensure circles don't appear partly off the screen. The next parameter for CIRCLE is the Y position, using r and mY again to keep the circle on screen**, and lastly, we supply the circle's radius, which ranges from the lowest radius value to the maximum.

**QL's coordinate system has 0,0 at the bottom left of the screen.

On line 60 the NEXT runs the loops until we've done 10 circles.

Originally I used FILL 1 to have filled circles but it causes the filled colour to spill out of the circles so I dropped that; the problem may be that overlapping circles confuse the fill routine.

To enable flash use:

FLASH 1

Which affects only what is rendered after the command. Unfortunately, FLASH doesn't work in high resolution mode.

There are other commands for drawing, such as the LINE command, which is versatile in that it can take a variable number of parameters, allowing for a single line or connected line to form complicated shapes. For example, to draw a single line:

LINE 0,0 TO 0,50

And for two connected lines:

LINE 0,0 TO 0,50 TO 50,50

QL has an internal clock which can be queried using:

PRINT DATE$

Which will result in something like:

1965 Feb 03 17:35:18

(I hadn't previously set the date and time.)

If you want to get just the day you can use:

PRINT DAY$

Which for me returned 'Wed'.

The QL has an internal speaker and we can generate a sound using BEEP like this:

BEEP 1000, 10

Which gives a short beep.

As well as being able to issue BASIC commands, QDOS instructions are also accepted, for example, use DIR to get a listing of the files on a microdrive cartridge by specifying the microdrive name like this:

DIR MDV1_

The results can be seen below:

As mentioned, the first microdrive is referenced using 'MDV1_', and the second as 'MDV2_' (case insensitive), and while it may seem odd to have the underscore included, you could think of it as a colon, just as you may in Windows, for example, use 'DIR C:'. In the above directory listing we can see the name of the microdrive cartridge is 'my_files', the number of available sectors and total sectors is 219 and 224 respectively, and the list of files follow.

A DIR listing can take about eight seconds - consider that it takes about 7 seconds to go through the microdrive cartridge loop once, which likely it will have to do to find the directory information. If you do another DIR without changing anything on the cartridge the results will be much fast because of the drive's cache.

To format a cartridge - which will wipe all files on it - use 'FORMAT' with the drive number and required cartridge name, for example, to format a cartridge in drive 1:

FORMAT MDV1_my_files

Will format the cartridge in drive one with the name 'my_files'.

Note that because Spectrum formatted microdrive cartridges aren't compatible with the QL they must be formatted in a QL to be usable and thus the cartridges cannot be used as a means to transfer files between a Spectrum and QL.

When I formatted a microdrive cartridge in the QL it took 30 seconds and reported 208/229 sectors, formatting it again resulted in 220/229 sectors and a third time 224/228 sectors, demonstrating that multiple formatting can increase the number of available sectors but decrease the total.

A BASIC program can be saved to a microdrive cartridge using 'SAVE'. the microdrive name, and the filename, like so:

SAVE MDV1_colour_test

When saving the colour demonstration BASIC program you saw earlier using the above command it took 15 seconds and you get no feedback if successful.

You won't be surprised that you use the same format to load but replacing 'SAVE' with 'LOAD'. It only took seconds to load the file I had just saved but perhaps that was due to the microdrive's cache. After loading you don't get any response other than the screen going blue just like when you list a BASIC program.

We will shortly look at two of the bundled software titles from Psion that originally came with the QL but first it's worth mentioning that like with floppy discs it's always a good idea to work with a copied version of the original microdrive cartridge, which can be cloned again in the future should the copy become unusable. Unfortunately, there is no built-in ability to clone microdrive cartridges, which seems like something basic that should have been standard. Fortunately, the bundled software does let you clone each software title individually and to do so you place the master cartridge in drive 2 and a blank cartridge in drive 1 (all files will be deleted on the cartridge). Then you use:

LRUN MDV2_CLONE

After pressing the enter key the computer will prompt for you to press the space bar to perform the duplication and each file copied will be displayed on the screen.

I found that Abacus takes 10 minutes to clone and consists of eight files, Quill took six minutes.

Now I will give a brief overview of the word processor, Quill.  Please see the QL user guide (see the Resources section) for full information on using the bundled software.

The software takes about 30 seconds to load from the microdrive cartridge but at 10 seconds in a loading screen appears, as below:

After Quill finishes loading you are presented with the main display:

I have to say I was impressed with Quill considering its age, it's easy to use but has lots of features that are easily accessible with reminders of the various functions and the shortcuts at the top of the screen and status information at the bottom. You can start typing and the program handles indents for you but as is the QL way you have to get used to using CTRL + arrow left to delete to the left of the cursor and CTRL + arrow right to delete to the right of the cursor.

Here I have started to write a story:

As you can see the text I entered is in green; for the title I accessed the underline feature which you get by pressing F4, then U, then typing the title. I wanted to enbolden 'Brits' so I moved to the 'B' in Brits, pressed F4, then P, and used the arrow keys to move through 'Brits' and it changed to bold, shown in white. I also centre justified the title by moving to the title, pressing F3, J for justify, C for centre, which also affected the rest of the document so I moved to the first paragraph and pressed L to left justify.

I saved the document by putting a cartridge in microdrive 2 then pressed F3, then S and typed the filename I wanted and pressed enter. Initially I used 'brave_Clive' but the program responded with 'not a valid quill file'; instead I used clive, which it accepted, taking 15 seconds to save. Because Quill appends '_doc' to the filename you specify, perhaps it gets confused if you use a filename with an underscore. You can load a previously saved document with F3, then L and type the filename followed by enter. I specified 'clive', rather than 'clive_doc', and it loaded the file no probably, taking just 3 seconds.

Help can be called up by pressing F1, wich takes 10 seconds and requries the Quill cartridge to be in microdrive one; you will also need the cartridge in the drive when printing. Here is the help screen:

You can then type what you want help on and a help screen will be displayed, which, is this example I typed 'insert' and pressed enter:

The ESC key returns you to your document.

Next we will look at Abacus, the spreadsheet program, which is another well thought out piece of software, which also took about 30 seconds to load. Its loading screen can be seen below:

Abacus' main display follows, which shows the familiar shortcut reminders at the top and status at the bottom, as with Quill:

The currently selected cell is marked with a red rectangle and the cell reference is mentioned at the bottom of the screen. You can select different cells with the arrow keys, which scrolls the screen as necessary. Help can be accessed with F1, the prompts at the top of the screen can be toggled on/off with F2 to give more space, and F3 lets you select from various commands. You can jump to a cell by pressing F5 and typing the cell reference (e.g. c3) followed by enter.

In the next screen you can see a few cells in which I've entered data:

Numbers are entered as expected by text must be preceeded by double quotation marks (if you forget and start typing text without quotes you will have to press escape and then type double quotation marks as it assumes you was typing a formula). Use CTRL + arrow key left or CTRL + right to delete to the left or right of the cursor respectively.

The next screenshot shows that I have finished putting together my simple spreadsheet:

I right justified 'Total:' in cell A:6 by pressing F3, then J, then pressed enter twice, then R, followed by the range (A6:A6). Additionally, I calculated the total number of units sold by entering the formula sum(b2:b5) in cell B:6. By the way, the units sold values I pulled from Wikipedia.

A spreadsheet can be saved by pressing F3, S, and the typing the filename followed by enter ('_aba' will be appended automatically to the filename). If you want to clear the spreadsheet press F3, Z and enter, and to perform a load, press F3, L, type the filename and press enter. Abacus data can be exported for use in Quill, Archive and Easel, and data can be imported from Archive or Easel.

Unfortunately the QL was plagued with problems from the start, having delayed delivery and technical problems, and reportedly only selling 150000, before being discontinued in April 1986, which was at the time of the Amstrad takeover of the Sinclair brand and products. If the QL had at least maintained some backward compatibility with the Spectrum it may have proved more popular but the differences in architecture would have made such a feature costly. It also didn't help that the QL was launched two weeks before the impressive Apple Macintosh 128K sporting a GUI, which may have drawn people's attention away from the QL, although the Macintosh was in a different (more expensive) price bracket.

Having microdrives as the QL's main form of storage was a poor choice even if Sinclair's intentions were good, considering that even without the unreliable nature of the microdrives, the use of floppy drives would have been a more welcome decision considering how much faster (or at least some drives) and higher capacity floppies were and more widespread in the world of electronics.

Emulators

Obtaining a QL can be expensive especially in working condition but a cheaper way to experience a QL is by use of an emulator, which simulates a QL on a modern computer. Please check out this site for a list of QL emulators:

https://www.rwapsoftware.co.uk/emulators.html

I tried out QPC2 v5, which uses the SMSQ/E variant of the QL operating system, and can run on Windows XP or higher, although Windows 10 is recommended. The emulator can be downloaded from:

https://www.kilgus.net/qpc/downloads/

I downloaded using the link 'QPC2 v5.02 (x86) executable files only', and once downloaded I extracted and double-clicked the QPC2.exe file. It pops up with QPC configuration window:

This window pops up everytime you start the emulator but you can click the checkbox 'Don't show this dialog on next startup' to prevent it from showing. There are various buttons you can click on for further configuration options, for e.g., 'Devices':

And 'SER/PAR' (serial/parallel):

I kept everything at default and clicked OK, then the main QL window appeared (there is no F1/F2 prompt):

In the above screenshot I've typed a simple BASIC command to display some text. As you will notice, there is a lot of empty space in the window, lowering the resolution causes the QL 'screen' to take up more of the window but then the window will also be larger.

Unfortunately the emulator doesn't support microdrives from what I can tell but it does have support for virtual floppy and hard disk drives. Wanting to try out some software I stumbled upon a 2019 amateur cyberpunk text adventure called game called 198? which was especially designed for the QL.

It can be found at:

https://qlforum.co.uk/viewtopic.php?t=3072

I downloaded and extracted the file and set the emulator to boot off 198adDisk ImageFinal.IMG file by clicking the Devices button in the QPC configuration window and setting FLP1 to use the floppy disk image file by clicking on the open button, navigating to and selecting the file and clicking Open. I set the drop-down selection under Boot options to use 'flip1_'. To deal with the window issue I found that setting Resolution to 512 x 384 and Window to 1024 x 768 (2x) worked as other combinations caused a glitched display when booting off the virtual floppy (there is still the large black area toward the bottom of the window though). The title screen:

Here is a screen of the game started having pressed a key as instrcuted:

And a screenshot after giving a command:

Peripherals

A wide range of peripherals and other types of add-ons were developed for the QL, some of which you can find more about in this section.

Some Sinclair QL peripherals are viewable on the Centre for Computing History's site:

https://www.computinghistory.org.uk/cgi/archive.pl?type=Peripherals&platform=Sinclair%20QL

Others can be viewed on the SINCLAIRQL site:

http://sinclairql.emuunlim.com/hardware.html

Centronics printer interfaces were available, allowing the use of a parallel printer, some of the interfaces could only be connected to SER1, others either serial port.

Tips

Microdrive

Microdrive cartridges formatted on a Sinclair Spectrum need to be reformatted for use on a QL.

Some programs are hardcoded to run from the first microdrive only.

Software


Troubleshooting & Repair

Teardown

Although the videos in this section contain teardowns of the QL, I will briefly go over the basics of taking the machine apart - see the following videos for more details. Remove the four long screws from the underside toward where the ports are located and the four short screws on the opposite end located lower down. Carefully lift up the top part of the case, mindful of the keyboard flat cables, which you will need to carefully pull out. Additionally, there are a number of wires that terminate in a 6-way connector soldered to the mainboard; if you are replacing the keyboard membrane then you can avoid the need to desolder the aforementioned wires and instead rest the top piece of the case on something so it puts no strain on the wires.

General

A series from YouTube user Noel's Retro Lab including overview, diagnostic, key replacement, cleaning, history, microdrive repair:

Keyboard

Like with other Sinclair computers, the keyboard membrane of the QL tends to fail over time so if you find that your QL doesn't respond to some keys or none at all then likely the membrane will need to be replaced. Although the Spectrum+ keyboard appears similar to the QL's there are differences in the keys and the membrane cables are different.

Please see this video that details the keyboard issue and shows the fix:

If you have sticky keys then try washing with hot soapy water the keyboard mat that sits between the keyboard membrane and the keys.

Microdrives

If, when trying to load from a microdrive cartridge you get this error or similar:

At line 8 bad or changed medium

Then the cartridge may be faulty but it may just need the felt replacing.

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