Remembering the Sinclair ZX Spectrum: A Milestone 8-Bit Computer Turns 40

Is it truly the 40th anniversary of the Sinclair ZX Spectrum? Time has flown by!

I couldn’t let this momentous day pass without penning my thoughts. Therefore, I compiled this piece at the last moment, drawing from material I had previously written for a now-defunct blog.

First Computer At Home

The Sinclair ZX Spectrum holds a special place in my heart as it was the very first computer I owned.

Improving on the ZX81

Much like its predecessor, the ZX81, the Spectrum was heavily promoted in the electronics magazines I frequented during the 80s.

Launched in 1982, the Spectrum introduced several enhancements over the ZX81, including vibrant color, sound capabilities, increased memory (16/48 KB as opposed to 1 KB), and a better keyboard.

Additionally, its ROM was significantly larger—16 KB, double that of the ZX81.

The Spectrum featured a Z80 microprocessor that operated slightly faster than that of the ZX81 (3.5 MHz versus 3.25 MHz), and it eliminated the previous model's FAST and SLOW modes by merging the best of both.

Though the Spectrum’s rubber keyboard didn’t measure up to those found on the Apple II and BBC Micro, it was certainly an improvement over the ZX81’s membrane keyboard.

Some argued that the Oric-1 had a superior keyboard. Regardless, it was a significant upgrade compared to the previous model.

Programs were typically stored on cassette tapes using a standard audio cassette recorder. The Spectrum's cassette interface ran at 1500 bps, making it roughly five times faster than that of the ZX81.

Alternatively, the optional Microdrive could be used, which was an economical yet unreliable floppy disk alternative later utilized in the Sinclair QL.

Despite its advancements over the ZX81, the Spectrum remained a compact and straightforward machine, aimed at the more budget-conscious segment of the market.

It had limited external connectivity, with a sole expansion port that permitted the addition of devices such as the ZX Printer, Sinclair’s Interface 1 and 2, and various third-party peripherals.

These expansions allowed the Spectrum to connect to joysticks, Microdrives, modems, and serial printers.

Becoming a ZX Spectrum Owner

My interest in computing began in high school during the early 80s, sparked by our computer studies class. However, the Apple II and BBC Micro we used were quite pricey, making them inaccessible for most families.

When my computer studies teacher offered a Sinclair ZX81 for sale, I was eager to buy it. Sadly, by the time I got my parents on board, another student had already purchased it.

A few months later, my parents surprised me with a 16K Sinclair ZX Spectrum as a Christmas gift! I was overjoyed and quickly forgot about the ZX81.

I will always remember the excitement of loading the Horizons cassette for the first time and playing games like Night Flite and Horace Goes Skiing.

Wanting to Program

The prospect of owning a programmable computer with a built-in sound generator was incredibly appealing to me as a child. The Spectrum’s limitations didn’t bother me much at that time.

It was my Spectrum, and I was just thrilled to have anything I could use at home.

Over the months, I delved into every facet of the Spectrum and thoroughly read all the manuals.

I learned to code using the Spectrum’s version of BASIC and even ventured into ‘machine code’ (Z80 assembly language).

The Spectrum’s BASIC supported graphics and sound—unlike other machines like the Commodore 64—making it accessible for beginners to experiment.

Graphics

For its price range, the Spectrum’s graphics were quite impressive at 256 x 192 resolution with 8 colors (or 15, including ‘bright’ versions).

However, its color attribute system limited each 8 x 8 block to just two colors.

Making Music

I attempted to create music and percussion sounds by coding my own software. Over time, I became increasingly dissatisfied with the Spectrum’s sound capabilities.

Similar to the Apple II, the Spectrum could only produce sound as a series of pulses or clicks, consuming processor time without offering proper control over waveform or volume—plus, it only had one channel.

The Spectrum’s BASIC manual included a ridiculous note in its sound chapter, claiming that it could only play one note at a time because it had a single speaker. Even as a child, I found that hard to believe!

Software techniques could help create more intricate sounds, but the absence of a dedicated sound chip (like those in the BBC Micro or Oric-1) meant it wasn't the best choice for anyone interested in music production.

Sound Add-On

I had an interest in electronics from an early age, having previously tinkered with various circuits and audio amplifiers.

Frustrated by the subpar sound generation, I designed and built a circuit to connect an external sound chip, which I had found in the Maplin catalog when I was around 14–15 years old.

I was thrilled when my sound generator add-on worked flawlessly, and I used it for weeks. But disaster eventually struck...

There wasn’t enough space at home to keep the Spectrum set up permanently, so I stored it away every night. This led to the polarizing key on the edge connector—connecting my sound circuit to the Spectrum’s expansion port—wearing out over time.

Without a working polarizing key, the connector shorted out the contacts on the Spectrum’s PCB, damaging the ULA chip.

I reached out to Maplin, and they kindly provided a free replacement connector. However, after the Spectrum was repaired, I couldn’t afford to risk damaging it again and ceased my experiments with add-ons.

New Models — Too Late for Me

In 1984, the Spectrum+ was released, which was essentially a 48K machine housed in a different case with a new keyboard—but it still lacked a dedicated sound chip.

At that moment, it felt like the Spectrum would never receive upgrades in that regard, prompting me to explore computers with superior sound capabilities.

That’s when the Commodore 64 caught my eye.

Its SID chip, responsible for sound, resembled a mini-synthesizer—leading me to transition to that machine soon after. (But that's a tale for another time...)

By 1986, it was somewhat frustrating to see Amstrad acquire the Spectrum and Sinclair brand, releasing new and enhanced models, starting with the ZX Spectrum +2.

In addition to an integrated cassette recorder, the Spectrum +2 boasted more RAM.

Most importantly, it finally included a sound chip!

Had it been released sooner, I might have remained loyal to the Spectrum—even though the Commodore 64’s SID chip was still more advanced.

The Smell of the ZX Printer

Towards the end of my time with the Spectrum, my parents gifted me a ZX Printer for my birthday.

While it was a nice addition, I was slightly disappointed that it couldn’t print on regular paper and was rather small in size.

The ZX Printer required its own special rolls of aluminum-coated paper, which were quite pricey, especially given their small size!

It was a novelty to print screenshots and program listings. I recall attaching a program listing to a school project and feeling somewhat embarrassed about its narrow, curled-up, silver-colored paper.

Ultimately, the printer had limited practical value.

Whenever I used the ZX Printer, I found myself wondering whether the burning aluminum smell it emitted was harmful!

During the time I owned a ZX Printer, I remember that Oric computers had a compact printer that could produce four-color prints on narrow rolls of regular paper.

The Oric’s superior printer and sound capabilities did make me a bit envious.

Conclusion

Regrettably, I had to sell my original 16K Spectrum in the 1980s to fund my next computer, the Commodore 64.

However, in 1988, I acquired a second-hand 48K ZX Spectrum, which I still possess.

Unfortunately, the condition of my replacement Spectrum was not great when I bought it. This was disappointing because my original 16K model was in pristine condition.

Occasionally, I set up my ZX Spectrum again. Those old cassettes evoke a flood of memories, and I can still recall some BASIC demo programs and Z80 instructions, like DJNZ!

Do you have any nostalgic memories of using the ZX Spectrum? Feel free to share your thoughts in the comments below.

If you enjoyed this article, you might also like these pieces:

Vintage Computers Microcomputers from the 70s and 80s that meant something to me

My Programming Journey 1: The Cereal Box and Knitting Needle Computer I was exposed to ideas about logical thinking years before I started programming

External Links

• Happy 30th Birthday Sinclair ZX Spectrum (The Register)
• ZX Spectrum is 40 (The Register)
• ZX Spectrum (Wikipedia)

Note: This is an updated version of an article I previously published in 2018 and 2020 on two now-defunct blogs.