OS: Sinclair Basic
Sinclair's first computer! ...
This computer was presented in 1979 and sold from 1980 until 1981, already a little bit but let's find out together.
One of the first home computers that brought information technology into our homes was built with a view to saving and in fact, as you can see, there isn't much. Everything is controlled by the Z80 microprocessor which takes care of practically everything, from video to communications with the RAM, keyboard and the outside world. The case is made of plastic and does not even have screws, it is kept closed with plastic latches (similar to rivets). The keyboard is built on top of the pcb with a membrane or rather a film that closes a contact on the printed circuit. The RAM was only 1kb and used a 4kb ROM for the operating system, the classic Sinclair Basic that we know well by now !.
This computer was even sold in a mail order kit, you could buy it for a low price, at the time £ 79.95 and £ 99.95 for the assembled version! note already the pricing policy to make them look like less than £ 100.
The computer, even if it was really reduced to the bone, was not too bad at the time and being able to have a small programmable computer in Basic for that price was a good initiative.
The production lasted only one year and was soon replaced by the ZX81 due to some of its defects, mainly there was a video refresh problem that when a key was pressed the screen flickered because the processor was busy decrypting the given commands and could not simultaneously manage the video output, there was therefore a small interruption. The keyboard was very uncomfortable not to say unusable, there was already to become familiar with the strange system adopted by Sinclair in typing the commands, in addition the key did not have a stroke and if you did not press the key centrally enough you risked not to have the command written. The ZX81 in fact solves the video problem with a component dedicated to this and slightly improves the keyboard with a membrane.
Below are the communication ports of the computer, we find 3 3.5mm jacks, yes all the same, the first on the left (seen from behind) is the microphone signal of the recorder, the second is the headphone (or audio signal) and the one near to the TV connector is the 9V DC power supply with the central pin (better to say the tip) positive and the bottom negative. This jack are all mono, so they only have 2 contacts, the problem is that they can be easily interchanged .. be careful not to plug the power supply jack into one of the others, otherwise we fry the computer.
Slightly higher there is the modulator connector to be connected to an RF cable TV and at the end an expansion connector
Nice is not it?
Well, below is the classic computer screen that will accompany all models up to the Spectrum 48k.
Think back then it was no small thing to have the opportunity to build a computer all by yourself with a processor, a ROM and a RAM plus a handful of logic components.
Even though the computer is very cheap, with no colors, no graphics capabilities, some games and adventures were made. Today with the greater knowledge of the processor features they have also managed to create incredible games for this computer given its reduced memory, which was unthinkable at the time.
Finally we talk about the price, very cheap when released, now this computer costs up to 8-10 times its initial price, it is considered a rare and sought-after computer. Unfortunately the models that are found today often have scratches or loose parts due to contact with the cables, up to broken pieces on the body or cut because modified, this only increases the price of the “perfect” model.
We at Retrofixer are not looking for perfection, but to be able to save and preserve these machines, watch this video about repairing a ZX80!