4 Nov
2000
4 Nov
'00
4:06 a.m.
Allison wrote:
To be exact the z80 has
[list of registers
deleted]
You forgot IFF2. :-)
And both the Z-80 and 6502 have at least one more
bit that's "sort of" programmer visible, the NMI
edge-detect flop.
6502
SP 9BIT (HIGH BIT =1)
It's either 8 bits, or 16 bits with the high 8 being stuck at "00000001".
There's no meaningful reason to consider it a 9-bit register. I personally
only find it sensible to count the bits that change, so I call it 8.
STATUS 8BIT
7 bits, or 8 with one bit stuck high..