4 Apr
2006
4 Apr
'06
8:12 p.m.
On Tuesday 04 April 2006 10:23 pm, Don Y wrote:
Yes. And I often wished that they'd had one that would work with BC, as
well... :-)
The typical usage was HL & DE for source/destination pointers and BC as
length/byte count.
Yup! I just like orthagonality, I guess...
Blame that H-11 that was my first hand-on exposure to a computer for spoiling
my expectations in that regard. :-)
<...>
That's what Osborne thought when they used it for _the keyboard interrupt_ (if
I'm remembering right) and then along came Turbo Pascal and Mix C and you had
to run a patch program or upgrade to a 1.21 rom (in the executive) to get 'em
to work at all.
Makes sense to me. My fiddling monitor program used a couple of those, I
think, but not most of them.
<...>
We would often develop our own interpreters to make some of this
stuff more efficient to code. This would get coded in-line
with appropriate macros. For example:
STATE IDLE
ON '0' THRU '9' GOTO IDLE EXECUTING Accumulate_Digit
ON BARCODE GOTO TEST EXECUTING Clear_and_Read_then_Test
ON CLEAR GOTO IDLE EXECUTING Clear_Accumlator
ON ENTER GOTO TEST EXECUTING Test_Value
ENDSTATE
STATE TEST
ON GOODVALUE GOTO ACCEPT EXECUTING Process_Value
ON BADVALUE GOTO REJECT EXECUTING Signal_Error
ENDSTATE
So, with ~25 bytes, I can code a numeric data entry routine
(trivial example) in a way that actually is reasonably easy
to read.
Macros were one thing I never really got going on, although one of the books
I have on hand here that deals with this stuff (I forget which one it is now,
and if it's z80-specific or cp/m-specific) was so heavily awash with them
that I had trouble wrapping my head around it. I should probably dig that
book out of whatever box it's in and have another look one of these days.
<...>
THogh this caused all sorts of problems when I got my first
ICE! :-( (think about it :> )
Never used one, so I'm not sure how you mean here.
For the z80? I'd sure like to see that if so.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Yeah. Though
XTHL was another one...
As was PCHL. But, XCHG was lots of bang for the buck (4 clocks?) But I never
used most of that stuff. Never got around to doing anything
with the index registers, the alternate set, or a lot of those
"specials" that
Alternate register set was ideal for interrupt service (assuming
IRQs aren't nested *or* you restrict the alt registers for use by
a single IRQ that can never interrupt itself). Consider the
cost of saving all of that state and restoring it before RETI
and you can see how quickly you can save a lot of time! were added. I
kinda liked relative jumps, though, since it made it way
easier to do relocatable code and plus they were a byte smaller. :-)
A favorite trick was to finish a product. Then grep for all
CALLs. Sort this list to come up with the N most common CALLs,
and then assign those to the "unused" RST's. You could often
save 500 bytes of code with that 10 minute exercise... DB 'Hello, World!'
<insert next instruction here>
Just so. Or, using INR M to 'test' flags.
Yep! Sometimes I
like the absolutely minimalist approach to things, too. One
of these days I'm gonna dig that code out, burn it, and see how small a
z80 box I can build that'll still prove useful for all sorts of things.
I sure have enough of those parts on hand here...
I have a tiny multitasking executive that runs in a handful of
bytes. Slick as snot -- if you adopt its coding style.