Retromaster’s Electronics Projects

…related to old computers and other assorted stuff…

An Older Project Revisited: A2601

Posted by retromaster on August 16, 2010

Having made quite a bit of progress with UFE, I’ve decided it’s time to take a little break from it while I wait and see how recent developments in the manufacturing front pan out (sorry, cannot give details on that yet). So, I am now revisiting a never-before-released project of mine that is almost five years old now.

The project is an ATARI 2600 clone on FPGA, including 6502 and TIA cores in VHDL and dedicated PCB layout, all developed by me. The design fits in a 100K gate Xilinx Spartan 3E, and works quite well in the simulator. The PCB design contains the FPGA, resistor-ladder DACs for video and audio, custom joystick input ports and flash memory for storing ROMs. Few years ago I even built a prototype. It worked well, but unfortunately it did not survive, since my PCB-making techniques were not as advanced back then…

So, what’s new this time around? Basically, a reworking of the PCB layout that fits in a smaller case and contains a single input port for a Genesis/MegaDrive gamepad instead of custom-wired pads. I’ve ended up choosing MegaDrive pads because they are commonly available, very easy to drive and they contain the necessary auxiliary buttons (start/select etc.). I’ve already started manufacturing the board and the photo above shows the work in progress. Hopefully, all will go well and next time I’ll be posting working photos of the board…

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