Spectrum is 35!

35 years ago today, long before my time, a ZX Spectrum was first launched (23.04.1982).

Here I am holding one of the early models released – Issue One Spectrum often identified by its grey coloured keys . Only approx. 16,000 were made making it one of the least common and most collectable model across the whole Spectrum range.

Although the Spectrum has undergone many changes in its design, the rubber-keyed model remains one of the most iconic 8-bit computers, still loved by hundreds around the world today.


Official 35th Birthday Celebration will be held on the 28th of October 2017 in The Centre For Computing History in Cambridge (England). Pre-order your tickets here.


What is Issue 1.5?

“Issue 1.5” is an unofficial name used to describe an early issue 2 Spectrum incorporating leftover issue 1 parts. Basically, a fancy name for an issue 2 Spectrum that is a bit more special and a bit less common than any normal (later) issue 2.

Apart from using an Issue 1 ULA (5C102E) with the mandatory cockroach modification, early examples also encompass case parts specific to issue 1 Spectrums. Owing to little interest or demand they aren’t as collectable so don’t tend to fetch the high prices actual issue 1 machines command. Hence it could also be called “Poor Man’s Issue 1”.
Another name for such machine I’ve come across is Prototype Issue 2 but that name doesn’t sit well with me so I’ll stick to calling it “Issue 1.5”.


Cockroach modification

Externally it can be difficult telling it apart from an issue 1 Spectrum, especially when featuring a grey keymat normally associated with issue 1 machines. (Interesting little-known fact: Not all issue 1 Spectrums have grey keymats, and equally a grey keymat isn’t always a token of issue 1 machine.)
Even the serial numbers stamped on the bottom of the case aren’t always conclusive with first issue 2 issue 1.5 machines appearing as early as 15,000 and issue 1’s being spread out all over the place and appearing randomly where you wouldn’t normally expect them to.
It may be a coincidence but none of my issue 1.5’s feature an adjustment hole present on issue 1 cases – it could be a distinguishing element.
Look out for various types of moulds when met with a case embodying an adjustment hole – note the position of the logo:



The only certain way to be sure what issue is your Spectrum without opening the case is looking through the hole in the expansion port at the rear of the case.

Issue 1:
Look for a solitary orange capacitor

16K Issue 1 Rear View

16K Issue 1 Rear View

Issue 1 with 32K daughterboard expansion:
Lots of orange capacitors inside

48K Issue 1 Rear View

48K Issue 1 Rear View

Issue 2:
Like a normal issue 2 (the colour of the capacitors may vary)

Issue 2 Rear View

Issue 2 Rear View

Issue 1.5:
Like issue 2 but with visible wires (connecting to the cockroach)

Issue 1.5 Rear View

Issue 1.5 Rear View

And here are some hi-res photos of topless Issue 1.5 Spectrums for your viewing pleasure:


Number 9

This is the earliest known released Spectrum to be around!
The serial number is 001-000009 meaning it’s exactly 9th Spectrum to roll off the production line.
The datacodes on the chips suggest the board might have originally belonged to a later issue 1 Spectrum. It has also been fitted with a replacement faceplate.

And here’s me holding it!
Seeing one of the earliest Spectrums in real life, what an honour that was!


Issue 1 Blue Keyboard


Not all Issue 1 Spectrums come with light grey keyboards, although vast majority of them do. Occasionally there might be Issue 1 Spectrum with a darker coloured keyboard, such as this one. It’s not completely alike the later keyboard revision – it only shares the same colour. The texture still feels the same as the original light grey key mat.



Spectrum No. 515

There were around 16,000 Issue 1 Spectrums made.
This one is believed to be the 515th Spectrum to roll off the production line.
As early as the serial number is, even earlier serial numbers are known to be still in circulation.


Note the small hole at the back of the case mostly used on Issue 1 Spectrums. Its purpose is to facilitate an access to the area of the motherboard which enables the picture calibration.



Rare grey rubber keyboard specific to most Issue 1s.
This one is in a fairly good condition, with all the red markings still present, even rarer!


Issue 1 Spectrum motherboards feature handdrawn tracks, as opposed to latter machine printed tracks.
Very early Issue 1s, such as this one, also feature a handwired dead coachroach factory modification.

This 16K Spectrum is part of my personal collection, it is in a fully original state, and no changes/modifications have been carried out.