The world around the Sinclair Spectrum ZX48

While the Commodore 64 dominated the US market; in Europe and many other places in the world, the Spectrum was a more popular choice. The ZX48 was a worthy successor to its predecessor, the ZX81. Introduced by Sinclair Research Ltd in 1982, the Spectrum may not have been technically more advanced, in fact it had the same CPU clocked faster; but it did not matter, the Spectrum had what everyone wanted: color, sound, and more memory; all at an affordable price. Its success was guaranteed and instantaneous, as it was the natural choice for loyal ZX81 users, who awaited this computer eagerly and were not disappointed. Its popularity spread worldwide, as no other computer could offer anything similar at that price point.

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The price made it very attractive!

The price made it very attractive! (Sinclair User)

World Best Computer

Specs showed significant improvements over the ZX81 (ZX Computing)

The price made it very attractive!

The US cousin of Spectrum, the Timex Sinclair 2068 (Timex Sinclair Catalog) 

The price made it very attractive!

Backwards compatibility was limited; you needed to avoid some basic commands to ensure things would run on the ZX81. (ZX Computing)

Spectrum Interfaces 

Following the ZX81, Sinclair came back with exactly what every user wanted. An improved model, with color and sound, that was still as affordable. So, the next challenge for Sinclair was to improve connectivity, and it had to be cool and affordable. It also had to be competitive with the new generation of computers. The solution proposed by Sinclair was the Sinclair Interface 1, designed to expand the functionality of the Sinclair ZX Spectrum. It was released in 1983 and was meant to be a general-purpose interface, and included a controller for the Sinclair Microdrive, a serial port, and network connectivity (QLAN). It was a failure, in every sense. Mostly because the main motivation to get it was the Microdrive controller, and the actual Microdrive was terrible. The rest of the functionality was seldom used by the average user: serial port, and QLAN networking.

So, what comes after the Interface 1. You guessed right: The interface 2, which was a lot less ambitious and probably more useful. It was just a joystick adaptor and a small ROM cartridge reader. Remember, in keeping the Spectrum's entry price low, the ZX48 did not have a joystick port. This does not make a lot of sense considering that this computer was meant to compete with the C64, MSX, CPC464, Coleco and other computers and gaming consoles of the time. So, the Interface 2 enjoyed some level of success, but mostly for using joysticks. ROM cartridges never picked up on the Spectrum.

Eventually there were several interfaces which added connectivity and functionality to the Spectrum. Most of those were made by third-parties and seemed to address the actual needs and desires of the Spectrum community.

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Expansion Interface

Alternative for expansion popped up everywhere. SP-DOS was a great attempt to make the Spectrum more mature. (Spectrum User)

Expansion Interface

Bulky and very industrial looking, here you have an expansion module that address all the issues of the Interface 1 (Spectrum User)


Eventually the expansion units became more serious, offering all-in-one solutions to connectivity (Spectrum User)


Just like people compete over how many ingredients you can add to you Starbucks coffee... (ZX Computing)

Joysticks and joystick mapping devices

Did I mentioned the Spectrum was meant to be an affordable computer? When the Sinclair planning team said affordable, they meant it. The other obvious requirement for the Spectrum was gaming capabilities (The ZX48 was going head-to-head against the C64 and other computers and gaming consoles of the time). So, the logical conclusion: you would probably want a joystick with your Spectrum. Well. It is not that easy.
The Sinclair Spectrum did not have a joystick port. You needed an interface to connect a joystick. I will give you a moment to process this. Now, please take a sip of coffee, tea, or whatever you are drinking, I know you will need it. This was a little bit of a mess. All games could be played with the keyboard. Different vendors sold different joystick interfaces. Some mapped joystick movements to keystrokes. Other used interrupt calls. Games were generally program for one, the other, and sometimes both methods. The point is that choosing an interface and joystick was a calculated decision. Unless... You could somehow map your joystick interactions to keys and interrupts as you wish. And of course, someone came up with this Joystick mapping devices that created more confusion and complexity. I told you to sit down for this.
Once you chose the interface you liked best, you would buy a compatible joystick, most of them were the Atari style, so it was fairly easy.

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Joystick Mapping
Joystick mapping device

Connecting a joystick to a computer should not be that complicated (Sinclair User)

Competition Joystick

This thing sparkles and shines. You are ready to compete... in some competition... like a pro (Sinclair User)

Programmable Joystick Interface

Metal shaft, with autofire, and a uniquely styled hand grip. It is also extremely sensitive. Just reading (Sinclair User)

Programmable Joystick Interface

The sheer complexity of simply connecting a joystick kills your desire to play. (Sinclair User)

Spectrum Keyboards

Loyal ZX81 fans who were eagerly awaiting the ZX48 knew that this computer will have everything they have been waiting for: more memory, color, sound, and a better keyboard. And Sinclair did not disappoint in any of these. The keyboard was actually better; but that doesn't mean it was a good, usable keyboard. It was just a minimal improvement over the ZX81 keyboard. So, you may be asking: how bad was it? Well, bad enough that a whole new industry of ZX48 keyboards developed. And they came in all flavors, from some that you just had to assemble, and solder parts, to other that required shipping your computer to have it undergo plastic surgery, and everything in between.

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DK Tronics Keyboard
ZX Keyboard

In some cases the keyboard offered a minimal improvement over what you already had (Sinclair User)

Saga Keyboards

The keyboard at the bottom looks pretty serious. That would actually be make your Spectrum fulfill its wildest dreams of being a PC (Sinclair User)

This should have been how the Spectrum should have been packaged (Sinclair User)

Sinclair Microdrive and other storage solutions

In another parallel universe, the microdrives would have taken off, and become a standard. They were small, portable, convenient. The disks were tiny compared to cassettes or diskettes. Form factor was great. Albeit slow, the whole thing was just nicely designed. Even the name "ZX Microdrive". And with time improvements could have been made to the speed. It could have been a standard and it could have been licensed to everyone. Unfortunately, the technology was bad, and the whole thing was quite unreliable, with some magnetic tape breaking inside. Adoption was very low.
Years later they were made standard (built-in) on the Sinclair QL... but we all know what happened to that one, right? Sad.
Other options became available for storage, with different disk formats. While these were more reliable, they were clunky, and no one really paid much attention to them. Also, there was really no good disk operating system, or set of commands to effectively operate these.
One unusual option was a "faster" cassette deck, which simply load and saved your program 4 times as fast. This was a significant improvement which never really took off.

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Light Pen
Sinclair Microdisk

The Interface 2 supported ROM cartridges. These were never really popular on the Spectrum (ZX Computing)

Spectrum External Drive

Yes. You could connect your Spectrum to a 3.5 inch drive. And by the way this was a more than just a drive (Sinclair User)

OS for the Sinclair Spectrum

Officially called Spectrum DOS. Who would have though you would end up with a real OS on your Sinclair (Sinclair User)

Sinclair Microdisk

Sinclair Microdisk. Rather expensive (Sinclair Catalog)

Sinclair Microdisk

Sinclair Microdisk. Rather expensive (Sinclair Catalog)

Sinclair Microdisk

A "fast" cassette player, that loaded programs at 4 times the speed of a regular tape deck! (Sinclair User)

Sinclair Microdisk

A "fast" cassette player, that loaded programs at 4 times the speed of a regular tape deck! (Sinclair User)

ZX Printer

Back in the 80s, standing in front of a computer retail window was magical. The Commodores, Sinclairs, Radio Shacks, all their accessories, television with some dumbed-down version of an arcade game. Everything looks awesome.
The one thing that did not cause any fascination from my part was the ZX printer. In fact, it looked just like the ZX81 printer. And just like the ZX81 printer, the ZX printer was useless. It printed on 4-inch paper (I get it, 32 columns, but still); was Sinclair hoping that someone would use their computers to print supermarket receipts? Why not make a A4, or letter size printer?
The printer itself was not bad. It was not good either. It resembled a POS (Point of Sale) ticket machine. I would guess the kids in the family could play "Shopping day" more realistically. Needless to say, no graphics on this printer, basic text.
Another thing that was actually bad was the claim of 50 characters per second. Indeed, the rate of print was 50CPS, but the max width was 32 characters, and then you needed to move to the next line and do a carriage return, because this was not bi-directional. So, there is no possible scenario in which you could print 50 characters in one second.
There is no information available on the number of units sold. My guess is that this was not a very successful product. A few competitors from third parties came about, also suffer from the same 32-character limitation.

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ZX Printer
Alphacom Printer

Basically the same thing as the ZX Printer. It has two buttons on the front panel! (Sinclair User)


The 20-40 printer is the standard Timex Sinclair 1000 printer, that is compatible with the Spectrum (Sinclair User) 

Size for reference

Size of the printer, for reference. Slightly bigger that a cassette tape (Sinclair User)

Spectrum light pens and other pen input devices

Just like any other computer of this era, the Spectrum had a light pen, or many light pens. Sinclair did not make an official light pen for the ZX48. The ones available were from third party manufacturers. The first light pens to come out for the Spectrum required some tinkering; the spectrum did not have a standard joystick port, so it was not an option to plug the light pen like in most other computers. The process involved opening your computer and connecting or soldering some cables. Life was not easy back then.
Later, and with the help of some magic, light pens connected via the MIC audio input, the clunky installation process. The new pens were a lot more successful and sold by many manufacturers. In terms of quality, there were as bad as any other light pen of the time. In terms of productivity and functionality: useless. But once again, the wow factor!
Graphic tablets were also available, but at a much smaller scale. While the offered more precision, they were still useless, and had a lesser wow factor; writing on a TV is almost a poltergeist kind of situation! 

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ZX Printer

Spectrum Speech / Voice Generators

If you were not able to impress your friends, mom, dad, or your kids with a light pen described in the section before, don't worry. The next item in the magician’s hat is a talking computer. Sinclair did not manufacture an official voice generator for the Spectrum, like Amstrad did for the CPC464. There were, however, plenty of options from third party manufacturers. Software came with voice generators, just like with light pens. However, there are some significant differences: light pens were useless without the software. For voice generators you could actually interact with them from BASIC. This was pretty easy: just put the string that you wanted the computer to say in a variable and send it to the right memory address. This meant that you could actually use the voice commands in your own computer program. Was this the first API/plug-in ever on a home computer?

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Talking Spectrum

Voice Input and Sound Samplers

If a light pen or voice generation is not sufficient to satisfy your multimedia cravings, we still have something else. How about voice input and sound sampling? If you were a kid, and no one ever listen to you, this was amazing: you would give an order and the computer will actually follow along.
The Spectrum could not sample on its own, it did not have the processing power. Samplers would have some external processing power to capture the audio signal and do some magical A/D conversion. The sampling rate was very low, as you would expect in the early ‘80s, so it will be impossible to sample music, but it worked for voice and sounds. Also, the limited memory of the Spectrum, would prevent you from capturing anything too long.
As it is the case with the Light Pen, there was not a lot you could do with this.

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Micro Command

Video Digitizer

Video digitizing devices were not that common back then. The first computer that made significant progress towards video capturing in the world of home computing was the Amiga. The Spectrum was a little ahead in this field. Further, the fact that a computer running a Z80 processor was able to digitize from a video signal is quite remarkable. Of course, most of the processing was on the digitizing device itself but still, this was a great feat for such a little computer. It was also fast. Granted the images were not great and will take a lot of space. If you were a developer working on an application or a game, this could help create incredible opening screens. Even better, if you were willing to crop the size of the captured images, and make sequence, you would get something that resembled a small video clip.

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ZX Printer

The community of enthusiasts around the Spectrum

The Spectrum was not just great out of the box, it was part of a thriving community of enthusiasts, hobbyists, and small businesses that spent endless hours of reading, writing, and sharing technical details, software, and peripherals. Home computers were no longer a fad, and a mature market with fan was slowly emerging. Clubs, local groups, and meet up were happening. As a result, a vast assortment of peripherals and software was created, making the Spectrum an even better investment. Soon, your Spectrum had a bunch of cool peripherals!

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Keyboard and memory

There were multiple pages with ads on the popular magazines (Sinclair User)


Hundreds of publication existed and were traded at local events and fairs (Sinclair User)


Specialized businesses offer peripherals and all kinds of services (Sinclair User)

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