Retro Computer

Hi All,
inspired by discussion in the Electronics Wednesday group I have decided to build a retro computer based on the 6502 chip. A couple of weeks back I received a backplane from tindie.com. I’ve completed the assembly and it’s ready to go.

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Yesterday I got my PCB’s back from China and have started building the single step/debug board.

The PLCC socket is for a Xilinx CPLD. I’ve reduced the debug circuitry from 6 or so 9 74’ series TTL chips to a single device.

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The schematic below is taken from the 6502 Hardware Manual. It’s the circuit suggested by MOS for debug/single stepping. The functions shown, things like button debounce and RDY signal control have been translated into Verilog and compiled into the CPLD. I will upload the sample code to the MHV GitHub account when I get a chance.

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Had a busy day yesterday and managed to complete the last of the 4 board designs I’ve been working on, the processor board.

I sent it to JLCPCB, a big outfit in China. Ordered 5 of each board, 20 in total. Two designs are 75x100mm, two are 100x100mm. The total charge, including DHL 3 day delivery was AUD50.

24 hours after the order was placed the boards are being silkscreened. If you have 30 mins free then https://www.youtube.com/watch?v=ljOoGyCso8s. It’s likely the same factory processing my order.

With any luck they’ll be delivered before next weekend.

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The logistics gods have smiled and DHL delivered my boards this afternoon. Now if they can do the same for Toll and my Element14 order I just may have something fun to do over easter.

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