4 Nov
2000
4 Nov
'00
12:10 p.m.
I'm not including internal temporaries that are
not
exposed in any way either. But depending on how your
hardware is wired, the NMI edge detect flop can have
substantial influence on how you write your interrupt
handler. Thus it is in fact programmer visible, though
not as much as e.g. the Z-80's R register.
It is a feature as they say. I like to use it for a RTC
heartbeat as you bang it with and edge. Hard to use
for CP/M as it hits the default FDB.
Z80 is as feature rich a cpu one could ask for at that time
or since. Z180 and all added some nice touches.
I happen to like the 8085 for mid sized tasks that are too
big for 8048/9 but Z80 may not fit as well. SIN/SOUT and
the four RST{5.5, 6.5, 7.5,TRAP) lines are handy for
some things. THose interrupts and IO lines offere more
than most minimal z80 systems without Zilog peripherals.
The 8085 is often forgotten despite being a decent chip.
Allison