monsonite Posted April 21, 2015 Report Share Posted April 21, 2015 Hi Jack & All, After yesterday's faux-pas of forgetting to reload the FPGA circuit (doh!) I have now made some progress with the VGA graphics at 800x600x60Hz - running on the ZPUino with 2MB of SRAM. My intention is to create a suite of simple tools, written in C, which can explore, and help to debug the application running on the ZPUino. The first of these is a Hex memory dump, which allows the contents of a range of RAM addresses to be viewed. Currently it's just dumping 1K x 16bit words - which is almost a screen full at a VGA resolution of 800x600. It takes just under a second to dump Address + 16 columns of hex memory contents. So it's not the fastest hexdump known to mankind. I believe that there are about 16K words left available to ZPUino, after it has taken care of the video RAM. This is in preparation for running a simulator of James Bowman's J1 Forth processor - so I can single step instructions and see what the memory and stacks/pc etc are doing. This is all leading towards a recreation of a simple "retro-style" computer - which runs entirely out of the PapilioDuo - fitted with a Computing Shield - for Keyboard, mouse, uSD and VGA support. At the moment, all the code is written on the ZPUino, but I am keen ultimately to explore other FPGA softcore processors. First I need a crash-course in VHDL/Verilog and simulation. I reach 50 in August - I have been looking at hexdumps since summer of '78 when a friend first dumped the memory of "Space Invaders" running on an early Z80 CP/M machine. He showed me which bytes to modify to alter the speed, add more bases/less spaceships etc. This is part nostalgic and part a learning exercise, programming doesn't come easy to me - but I'd rather code and keep my mind fresh - than do endless Suduko puzzles in my retirement. This will be the first, hopefully of a series of posts - as I undertake this project. Ken London Quote Link to comment Share on other sites More sharing options...
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