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Author Topic: Opcodes that should have been incorporated into the Z80 processor  (Read 17128 times)

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Offline Hot_Dog

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Opcodes that should have been incorporated into the Z80 processor
« on: March 13, 2012, 07:21:30 pm »
If too many opcodes are put into a processor, it becomes expensive.  But sometimes there are commands that we Z80 programmers use so often, we wonder why they don't exist in the Z80 hardware by default...we wonder why we have to code the routines ourselves. 

What are some that you wish the Z80 had?  Keep it simple--if time changes and the z80 becomes what we want it to be, we don't want it to be expensive ;D

For me:  add hl, a     sub hl, a     cp hl, reg16
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Offline calc84maniac

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #1 on: March 13, 2012, 08:42:13 pm »
eZ80 has pretty much everything I'd want. LD HL,(HL) ftw
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Offline Runer112

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #2 on: March 13, 2012, 08:52:38 pm »
mul reg16

EDIT: I don't think this is too high-end/expensive for Zilog to have added, I'm pretty sure the eZ80 had it.
« Last Edit: March 13, 2012, 08:59:17 pm by Runer112 »
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Offline calc84maniac

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #3 on: March 13, 2012, 09:10:58 pm »
Sure would be darn expensive in the 1980s :P
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Offline Xeda112358

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #4 on: March 13, 2012, 09:46:45 pm »
How about add hl,(**)? I would use that in cases where, say, HL is the offset into a buffer and the location of the buffer is at **. Or an instruction I just invented off the top of my head:

asjnc *

It performs add a,c \ sub b and does a relative jump if it did not go below zero. That might be useful, especially for line drawing and circle drawing and whatnot. I think it would be 16 cycles using the current processor.
« Last Edit: March 13, 2012, 09:47:01 pm by Xeda112358 »
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Offline ralphdspam

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #5 on: March 26, 2012, 02:47:11 am »
It would be nice if there were IX' and IY'. 

LD (REG 16),REG 16 and LD (REG 16),REG 16 would be extremely useful as well.
I wonder how the computer world would be if Zilog made the eZ80 immediately after the z80.  Nobody would have to deal with the 8086's yucky segment registers.  The world would be a better place.  :P
« Last Edit: March 26, 2012, 02:49:23 am by ralphdspam »
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ld a, 0
ld a, a

Offline C0deH4cker

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #6 on: March 26, 2012, 04:48:27 pm »
Quote from: ralphdspam on March 26, 2012, 02:47:11 am
It would be nice if there were IX' and IY'. 

LD (REG 16),REG 16 and LD (REG 16),REG 16 would be extremely useful as well.

Lol, those are the same.
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Offline DJ Omnimaga

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #7 on: March 26, 2012, 05:31:20 pm »
Quote from: calc84maniac on March 13, 2012, 09:10:58 pm
Sure would be darn expensive in the 1980s :P
I bet TI today would use the z80 power as excuse to the $100-130 price tags on their 83+ <_<
« Last Edit: March 26, 2012, 05:31:28 pm by DJ_O »
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Offline ralphdspam

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #8 on: April 02, 2012, 09:00:37 pm »
Quote from: C0deH4cker on March 26, 2012, 04:48:27 pm
Quote from: ralphdspam on March 26, 2012, 02:47:11 am
It would be nice if there were IX' and IY'. 

LD (REG 16),REG 16 and LD (REG 16),REG 16 would be extremely useful as well.

Lol, those are the same.
Yeah, I meant LD (Reg 16),Reg 16 and LD Reg 16,(Reg 16).  :P
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ld a, 0
ld a, a

Offline chickendude

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #9 on: June 18, 2012, 08:34:44 am »
Quote from: calc84maniac on March 13, 2012, 08:42:13 pm
eZ80 has pretty much everything I'd want. LD HL,(HL) ftw
A little bump, but ld hl,(hl) would have been great.
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Offline thepenguin77

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #10 on: June 18, 2012, 06:37:50 pm »
Quote from: chickendude on June 18, 2012, 08:34:44 am
Quote from: calc84maniac on March 13, 2012, 08:42:13 pm
eZ80 has pretty much everything I'd want. LD HL,(HL) ftw
A little bump, but ld hl,(hl) would have been great.

Oh, ho, ho, let's not forget bcall(_ldHlInd). At three bytes, it's only one byte bigger than ld hl,(hl) would be :D
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Offline chickendude

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #11 on: June 19, 2012, 12:21:11 am »
...and just as quick ;)
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Offline calc84maniac

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #12 on: June 19, 2012, 07:45:39 am »
Quote from: thepenguin77 on June 18, 2012, 06:37:50 pm
Quote from: chickendude on June 18, 2012, 08:34:44 am
Quote from: calc84maniac on March 13, 2012, 08:42:13 pm
eZ80 has pretty much everything I'd want. LD HL,(HL) ftw
A little bump, but ld hl,(hl) would have been great.

Oh, ho, ho, let's not forget bcall(_ldHlInd). At three bytes, it's only one byte bigger than ld hl,(hl) would be :D
But does it blend?
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Offline chickendude

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #13 on: June 19, 2012, 11:48:10 am »
I was looking through some old code of mine today and found "getHL()" all over the place. Btw, what is the ez80? It sounds pretty cool, what devices use it? :D
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Offline TIfanx1999

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Re: Opcodes that should have been incorporated into the Z80 processor
« Reply #14 on: June 20, 2012, 04:08:47 am »
No idea what devices use it, but it's essentially an updated Z80 that has (at least some,not sure how much) backwards compatibility. It was being discussed here because there were a couple of hobbyist projects going on attempting to build a "dream" graphing calculator. That was one of the chips being discussed, and largely for backwards compatibility with TI's stuff IIRC. Ease of transition was also a plus, as many current Z80 programmers would be (largely) familiar with it due to the similarities.
« Last Edit: June 20, 2012, 04:09:40 am by Art_of_camelot »
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