CPC ZERO Part 0: Intro, CPU and ROM
Reverse engineering the Amstrad CPC Revision Zero PCB made me wonder exactly what a 6502 based Amstrad would look like. So I have begin a project, which I’m calling the CPC ZERO, to design such a machine. The prototype PCB is so broken that it doesn’t give much of a starting point for a system, …. Read More
Amstrad CPC Revision Zero: Can It Be Fixed?
I think the genesis of the Amstrad CPC is fairly well known among retro enthusiasts: Amstrad hired some guys to design a machine based around the MOS 6502 processor, but the task was beyond them, Alan Sugar said “You’re Fired”, and a new team, headed by Roland Perry, were hired and came up the the …. Read More
Designing an Intel 8008 Computer. Part 1: Power, Clocks and Signals
The Intel 8008 was the second microprocessor, and the first 8-bit one, as well as being the first microprocessor to go on general sale. It’s an interesting and quirky beast which was constrained by bleeding edge technology and a curious edict from the Intel management. In terms of history, the 8008 was designed under contract …. Read More
Breadboarding With Diode Logic
I was thinking recently about OR gates. We normally do these with TTL logic chips but I wondered whether it would be possible to do the same thing with diodes. A quick Google showed that this was not merely a workable idea but something which has a name – ‘diode logic‘ – and which has …. Read More