The project has started off quite simple. I removed the case
and the RF modulator and gave myself a composite output. I then removed the 7805
and the coil and connected a USB-B socket to the board to take a 5V input. I am
now realising that the graphics memory requires 12V and -5V to power it as all
I am now getting on the screen is the flashing bars of doom. I am going to try
and replace this memory with a more modern device, preferably a single chip
rather than eight.
I am also thinking about what I want to achieve from the board.
I am definitely going to be attempting to recreate the Spectrums ULA using a
combination of some logic and a microcontroller, this will be challenging but
there is enough information about the part out there. I will probably also
create a new PCB as the old one uses a lot of one bit memory chips which eat up
space where the modern eight bit parts will be much smaller. I think the new
PCB will be more than achievable on a dual layer 100mm X 100mm board. I also
think that it would be a good idea to integrate two game ports rather than
having an edge connector on the back. Also, being able to use a modern keyboard
would be a plus as the Spectrums keyboard is horrific.
As I have no plans to use the original keyboard I have removed the connectors and replaced them with pin header which is much easier to connect to.
Parts used so far
- 1 x ZX Spectrum with issue 4b board from 1983
- 1 x USB-B connector
- 1 x Phono RCA connector
- Wire
Pictures from today
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