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Products => Computers => Vintage Computing => Topic started by: Alex Eisenhut on October 29, 2021, 07:28:59 pm

Title: An address generator
Post by: Alex Eisenhut on October 29, 2021, 07:28:59 pm
The idle thought occurred to me that a possible test of a 6502-based board is to drive the address bus through all states. The usual solution is to strap a "NOP generator" somewhere, but it seems easier to just replace the 6502 with a test harness that drives the address lines. The purpose being to observe the address decoding circuitry on the board.

A 40 pin DIP board with a 16 bit counter connected to the clock, plus whatever is needed for the phase signals.

Does such a thing already exist?
Title: Re: An address generatorlock,
Post by: Benta on October 29, 2021, 08:21:26 pm
The purpose being to observe the address decoding circuitry on the board.

A 40 pin DIP board with a 16 bit counter connected to the clock, plus whatever is needed for the phase signals.

Does such a thing already exist?

Yes. It's called an in-circuit-emulator (very expensive, though). But I fail to see the real purpose on a system as simple as 6502. Just follow the PCB traces, combined with the 74LS138/139 data sheets.
Title: Re: An address generator
Post by: Alex Eisenhut on October 29, 2021, 08:48:12 pm
The 6502 might be simple, but the system it's in might be crap.