4004 emulator - jump into instruction?
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GlideThestral
2015-11-12 01:00:10
I've tried to use old trick of jump to the second byte of 2-byte instruction (to save 1 byte & 1 cycle), like this:
jcn az xx1
...
db $28 ;; fim r8 ... instruction, used to skip next byte
xx1:
xch r0 ;; second byte of fim
...
but program gave wrong result.
Unfortunately I haven't time to investigate it now, so the question is: is it supposed to work and I made error somewhere or emulator doesn't support such tricks?
> is it supposed to work
I'm sorry to say, but it is not. This emulator was created so that it executes literally list of instructions, mnemonics - so it do not convert them to real hex codes. It is my fault and to fix this we need the whole thing to be rewritten. Though I hope to do this in future.
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