Turning a Top2005 EPROM Programmer into a Desktop Test Bench

Here’s a couple small demos that just toggle ZIF pins high or low.   Don’t have an IC plugged when you do this.   For these demos, the unused VPP and TOPBUS lines should be commented out in the ucf file.   This verilog file contains both demos, and only one should be compiled at a time – comment the other one out as we’ve done here.


module Vtest(MCLK24, ZIF);
input MCLK24;
output [40:1] ZIF;
reg [40:1] ZIF;
// Use the ZIF pins as a binary counter
always @(posedge MCLK24)
begin
ZIF <= ZIF + 1;
end
//
// Rotate a single bit around the pins in a shift register
// always @(posedge MCLK24)
// begin
// ZIF[40:2] <= ZIF[39:1];
// ZIF[1] <= ~(ZIF[40] | ZIF[39] | ZIF[38] | ZIF[37] | ZIF[36] |
// ZIF[35] | ZIF[34] | ZIF[33] | ZIF[32] | ZIF[31] | ZIF[30] |
// ZIF[29] | ZIF[28] | ZIF[27] | ZIF[26] | ZIF[25] | ZIF[24] |
// ZIF[23] | ZIF[22] | ZIF[21] | ZIF[20] | ZIF[19] | ZIF[18] |
// ZIF[17] | ZIF[16] | ZIF[15] | ZIF[14] | ZIF[13] | ZIF[12] |
// ZIF[11] | ZIF[10] | ZIF[9] | ZIF[8] | ZIF[7] | ZIF[6] |
// ZIF[5] | ZIF[4] | ZIF[3] | ZIF[2] | ZIF[1]);
// end
endmodule

More advanced verilog stuff is going to have to go into another article that you'll see in a few days.   It's a topic onto itself as you can certainly imagine!
We expect this article is interesting to different people for different reasons.   We can see a few target audiences, and have tried to include enough detail for each to get some use out of it.   Here's our guess on those audiences:

  1. Person who just wants a test bench.   Maybe not concerned with internals initially and just wants to twiddle pins and write some scripts.   But in time, his needs will probably grow to the point where he has to dig in deeper and write some verilog.
  2. Person who wants to do something specific to an IC, but doesn't know exactly how to develop the hardware to do so.   Lots of benefit here, as this hack provides a pretty generous set of capabilities and should have enough detail to allow more complex and semi-custom functions with a small amount of labor.
  3. Person who hates when EPROM programmers don't support device X.   You're always saying to yourself that you'd write it yourself if you just knew how...   So here you go, please share your work!
  4. Guy who just likes taking things apart.   Well this thing has been disassembled from the case to the software, to the internal logic structure.   Hope we've included enough detail to inspire you to tear down your own device, or at least given you a good story on what process we use in getting into the nuts and bolts.

Stay tuned for some more follow-up stores on this little box.   Until then....

Cheers,

-Openschemes


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