asm context issue? - Printable Version

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asm context issue? - britlion - 10-25-2011

sub a,3
end asm

I think this is expecting sub to be the basic context subroutine, not the asm subtract command, so fails to compile?

zxb 1.2.8-s758

Re: asm context issue? - boriel - 10-25-2011

According to the ZX Spectrum manual, the Z80 syntax instruction is sub N not sub a, N for 8 bits.
sub 3
end asm
should work ok.
Try this and tell me :?:

Re: asm context issue? - britlion - 10-26-2011


Looks like my reference may be incorrect:

SUB A,imm8
Operation Subtracts the immediate value from A.
Op Code 11010110 : [imm8]
Flags S Z H C are affected as defined
P/V detects overflow
N is set
T States 7

You're right. It looks like Zilog officially use SUB N - which is inconsistent with all their other instructions! How bizarre!

Re: asm context issue? - boriel - 10-26-2011

I used the speccy user manual to get the asm mnemonics! :mrgreen:
Anyway, I will try to make de ASM to allow SUB A, N also. :roll: