gfoot wrote:
Cookie13! wrote:
This also does nothing. Totally confused.
I know it's probably just a careless idiom, but note that this is almost certainly not true! It is quite hard to get a 6502 to do nothing, unless you stop its clock. It is probably doing something, but not what you expect, and
it is important to find ways to determine what that is. A good way to do that is to use a bus monitor. If you can slow your clock way down you can use an Arduino the way Ben Eater does. But better - and not too expensive - is to use an FX2 dev board as a logic analyzer and feed its capture file to Hoglet's 6502 decoder software. Here's a recent thread about that:
viewtopic.php?f=12&t=7710If your DMM has a frequency counter (My Aneng 8008 does and it's a pretty cheap DMM) you could also try setting up the VIA as a frequency generator:
Code:
lda #$FF
sta DDRA ; Set PORTA to OUTPUT
forever:
inc PORTA
bra forever ; or 'jmp forever' if you're using an NMOS CPU
If your VIA is working you should see 8 square waves on the PORTA pins, each half the frequency of the previous one.
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