I thought that would make a good first post.
My ZX81 only had a brief but busy time as my only computer. When I received it for my birthday, it had a massive 1024 bytes of RAM. The memory was shared between display, the operating system and the user programs. The display dynamically occupied memory, so as you increased the number of displayed lines it occupied more memory.
For Christmas I got the 16K RAM pack (sitting on top of the manual). This occupied the same mempry map as the on-board memory (you did not end up with 17K of memory).
One of the cost cutting measures of the design was the membrane keyboard. It was not particularly good and so there was a number of companies supplying better quality keyboard. The one above is from Redditch Electronics. To install it you had to open the case and pass the two ribbon cables through and replace the ribbon cables from the existing keyboard. This is similar to fitting a camera to the Raspberry Pi, but without all the supporting videos found on the Internet.
The other box is a sound card. The ZX81 expansion port allowed the addition of a number of devices, with the RAM pack as the last item. Using the AY8192 sound chip, it allowed the programmed generation of sounds. Certain games would also also make use of the sound generation.
Not shown is the cassette player used for storage. Not the most reliable of storage media.
I do seem to have misplaced the power supply. It may be in the box with the ZX-Spectrum, its successor.
My ZX81 only had a brief but busy time as my only computer. When I received it for my birthday, it had a massive 1024 bytes of RAM. The memory was shared between display, the operating system and the user programs. The display dynamically occupied memory, so as you increased the number of displayed lines it occupied more memory.
For Christmas I got the 16K RAM pack (sitting on top of the manual). This occupied the same mempry map as the on-board memory (you did not end up with 17K of memory).
One of the cost cutting measures of the design was the membrane keyboard. It was not particularly good and so there was a number of companies supplying better quality keyboard. The one above is from Redditch Electronics. To install it you had to open the case and pass the two ribbon cables through and replace the ribbon cables from the existing keyboard. This is similar to fitting a camera to the Raspberry Pi, but without all the supporting videos found on the Internet.
The other box is a sound card. The ZX81 expansion port allowed the addition of a number of devices, with the RAM pack as the last item. Using the AY8192 sound chip, it allowed the programmed generation of sounds. Certain games would also also make use of the sound generation.
Not shown is the cassette player used for storage. Not the most reliable of storage media.
I do seem to have misplaced the power supply. It may be in the box with the ZX-Spectrum, its successor.
