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Groups > alt.folklore.computers > #161804 > unrolled thread

OT: processor binary- or pin-compatibility, was [Re: Processor ISAs]

Started byRod Pemberton <NoHaveNotOne@bcczxcfre.cmm>
First post2016-04-01 21:22 -0400
Last post2016-04-17 02:37 -0500
Articles 18 — 10 participants

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  OT: processor binary- or pin-compatibility, was [Re: Processor ISAs] Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-04-01 21:22 -0400
    Re: OT: processor binary- or pin-compatibility, was [Re: Processor ISAs] Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-04-01 21:26 -0400
    Re: OT: processor binary- or pin-compatibility, was [Re: Processor ISAs] Bob Eager <news0006@eager.cx> - 2016-04-02 08:46 +0000
      Re: OT: processor binary- or pin-compatibility, was [Re: Processor Bogus@Embarq.com (Steve) - 2016-04-03 12:31 +0000
        Re: OT: processor binary- or pin-compatibility, was [Re: Processor Morten Reistad <first@last.name.invalid> - 2016-04-03 14:44 +0200
        Re: OT: processor binary- or pin-compatibility, was [Re: Processor Bob Eager <news0006@eager.cx> - 2016-04-03 18:53 +0000
          Re: OT: processor binary- or pin-compatibility, was [Re: Processor Bogus@Embarq.com (Steve) - 2016-04-03 20:07 +0000
            Re: OT: processor binary- or pin-compatibility, was [Re: Processor Bob Eager <news0006@eager.cx> - 2016-04-03 21:18 +0000
              Re: OT: processor binary- or pin-compatibility, was [Re: Processor "J. Clarke" <j.clarke.873638@gmail.com> - 2016-04-03 20:20 -0400
          Re: OT: processor binary- or pin-compatibility, was [Re: Processor "J. Clarke" <j.clarke.873638@gmail.com> - 2016-04-03 20:17 -0400
          Re: OT: processor binary- or pin-compatibility, was [Re: Processor pechter@pechter.dyndns.org (William Pechter) - 2016-04-04 15:53 +0000
    Re: OT: processor binary- or pin-compatibility, was [Re: Processor ISAs] roger.ivie@gmail.com - 2016-04-02 09:48 -0700
    Re: processor binary- or pin-compatibility, was [Re: Processor ISAs] "Charles Richmond" <numerist@aquaporin4.com> - 2016-04-04 17:24 -0500
      Re: processor binary- or pin-compatibility, was [Re: Processor ISAs] Bob Eager <news0006@eager.cx> - 2016-04-04 23:08 +0000
      Re: processor binary- or pin-compatibility, was [Re: Processor ISAs] Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2016-04-05 03:05 +0000
      Re: processor binary- or pin-compatibility, was [Re: Processor ISAs] Bogus@Embarq.com (Steve) - 2016-04-05 17:43 +0000
        Re: processor binary- or pin-compatibility, was [Re: Processor ISAs] Ahem A Rivet's Shot <steveo@eircom.net> - 2016-04-05 19:15 +0100
          Re: processor binary- or pin-compatibility, was [Re: Processor ISAs] "Charles Richmond" <numerist@aquaporin4.com> - 2016-04-17 02:37 -0500

#161804 — OT: processor binary- or pin-compatibility, was [Re: Processor ISAs]

FromRod Pemberton <NoHaveNotOne@bcczxcfre.cmm>
Date2016-04-01 21:22 -0400
SubjectOT: processor binary- or pin-compatibility, was [Re: Processor ISAs]
Message-ID<20160401212231.1c439bc6@_>
On Fri, 1 Apr 2016 22:48:32 +0100
James Harris <james.harris.1@gmail.com> wrote:

> On 01/04/2016 12:16, wolfgang kern wrote:
> > James Harris wrote:

> > [Z80 binary compatibility]

The issue of processor pin-compatibility versus
binary-compatibility comes up from time to time
on alt.os.development.

I decided to post a basic list for reference:

NEC V20 - pin compatible with 8088
NEC V30 - pin compatible with 8086
Cyrix Cx486 series - pin compatible with 80386
W65C802 - pin compatible with 65C02
6501 - pin compatible with 6800
68010 - pin compatible with 68010

NEC V20 - binary compatible with 80186
Z80 - binary compatible with 8080
8008 - binary compatible with 2200
KL5C8400 - binary compatible with Z80


Rod Pemberton

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#161805

FromRod Pemberton <NoHaveNotOne@bcczxcfre.cmm>
Date2016-04-01 21:26 -0400
Message-ID<20160401212654.16d3f9f0@_>
In reply to#161804
On Fri, 1 Apr 2016 21:22:31 -0400
Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> wrote:

> On Fri, 1 Apr 2016 22:48:32 +0100
> James Harris <james.harris.1@gmail.com> wrote:
> 
> > On 01/04/2016 12:16, wolfgang kern wrote:  
> > > James Harris wrote:  
> 
> > > [Z80 binary compatibility]  

> The issue of processor pin-compatibility versus
> binary-compatibility comes up from time to time
> on alt.os.development.
> 
> I decided to post a basic list for reference:
> 
> NEC V20 - pin compatible with 8088
> NEC V30 - pin compatible with 8086
> Cyrix Cx486 series - pin compatible with 80386
> W65C802 - pin compatible with 65C02
> 6501 - pin compatible with 6800
> 68010 - pin compatible with 68010

Correction:
68010 - pin compatible with 68000

> NEC V20 - binary compatible with 80186
> Z80 - binary compatible with 8080
> 8008 - binary compatible with 2200
> KL5C8400 - binary compatible with Z80
> 

Rod Pemberton

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#161819

FromBob Eager <news0006@eager.cx>
Date2016-04-02 08:46 +0000
Message-ID<dm9f78FflomU36@mid.individual.net>
In reply to#161804
On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:

> NEC V20 - binary compatible with 80186

That sort of depends on whether you limit yourself to the instruction 
set. The 80186 had a very different software interface to (e.g.) the 
interrupt controller.

-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#161866 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

FromBogus@Embarq.com (Steve)
Date2016-04-03 12:31 +0000
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<c1.2b8.3qdDy3$05p@NOVOSAD3.EMBARQ.COM>
In reply to#161819
Hi,

Bob Eager <news0006@eager.cx> writes:
>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
>
>> NEC V20 - binary compatible with 80186
>
>That sort of depends on whether you limit yourself to the instruction 
>set. The 80186 had a very different software interface to (e.g.) the 
>interrupt controller.

   According to "The Undocumented PC", the V20 did not support
undocumented 80186 opcodes.  It also had a mode where it
supported 8080 binary code.

Regards,

Steve N.

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#161868 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

FromMorten Reistad <first@last.name.invalid>
Date2016-04-03 14:44 +0200
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<7qf7tc-i61.ln1@sambook.reistad.name>
In reply to#161866
In article <c1.2b8.3qdDy3$05p@NOVOSAD3.EMBARQ.COM>,
Steve <Bogus@Embarq.com> wrote:
>Hi,
>
>Bob Eager <news0006@eager.cx> writes:
>>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
>>
>>> NEC V20 - binary compatible with 80186
>>
>>That sort of depends on whether you limit yourself to the instruction 
>>set. The 80186 had a very different software interface to (e.g.) the 
>>interrupt controller.
>
>   According to "The Undocumented PC", the V20 did not support
>undocumented 80186 opcodes.  It also had a mode where it
>supported 8080 binary code.

Also, it was noticably faster, especially with early multitasking
stuff like QNX and GEM. 

-- mrr


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#161916 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

FromBob Eager <news0006@eager.cx>
Date2016-04-03 18:53 +0000
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<dmd755Fs66uU1@mid.individual.net>
In reply to#161866
On Sun, 03 Apr 2016 12:31:39 +0000, Steve wrote:

> Hi,
> 
> Bob Eager <news0006@eager.cx> writes:
>>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
>>
>>> NEC V20 - binary compatible with 80186
>>
>>That sort of depends on whether you limit yourself to the instruction
>>set. The 80186 had a very different software interface to (e.g.) the
>>interrupt controller.
> 
>    According to "The Undocumented PC", the V20 did not support
> undocumented 80186 opcodes.  It also had a mode where it supported 8080
> binary code.
> 
> Regards,
> 
> Steve N.

I actually had some V30s on a few PCs (the V30 was to the 8086 what the 
V20 was to the 8088). The V3x was significantly faster than the 808x on 
multiply and divide, etc.



-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#161928 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

FromBogus@Embarq.com (Steve)
Date2016-04-03 20:07 +0000
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<c1.2b8.3qdR4T$05q@NOVOSAD3.EMBARQ.COM>
In reply to#161916
Hi Bob,

Bob Eager <news0006@eager.cx> writes:
>On Sun, 03 Apr 2016 12:31:39 +0000, Steve wrote:
>
>> Hi,
>> 
>> Bob Eager <news0006@eager.cx> writes:
>>>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
>>>
>>>> NEC V20 - binary compatible with 80186
>>>
>>>That sort of depends on whether you limit yourself to the instruction
>>>set. The 80186 had a very different software interface to (e.g.) the
>>>interrupt controller.
>> 
>>    According to "The Undocumented PC", the V20 did not support
>> undocumented 80186 opcodes.  It also had a mode where it supported 8080
>> binary code.
>> 
>> Regards,
>> 
>> Steve N.
>
>I actually had some V30s on a few PCs (the V30 was to the 8086 what the 
>V20 was to the 8088). The V3x was significantly faster than the 808x on 
>multiply and divide, etc.

   Yes I had a Zenith Z-100 and swapped out the 8088 for a while with
a V20.  It seemed to run 10 to 15 percent faster, on average .  It did
not like the 8087 I put in, so I went back to the 8088.

Regards,

Steve N.

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#161929 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

FromBob Eager <news0006@eager.cx>
Date2016-04-03 21:18 +0000
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<dmdfkqFs66uU2@mid.individual.net>
In reply to#161928
On Sun, 03 Apr 2016 20:07:53 +0000, Steve wrote:

> Hi Bob,
> 
> Bob Eager <news0006@eager.cx> writes:
>>On Sun, 03 Apr 2016 12:31:39 +0000, Steve wrote:
>>
>>> Hi,
>>> 
>>> Bob Eager <news0006@eager.cx> writes:
>>>>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
>>>>
>>>>> NEC V20 - binary compatible with 80186
>>>>
>>>>That sort of depends on whether you limit yourself to the instruction
>>>>set. The 80186 had a very different software interface to (e.g.) the
>>>>interrupt controller.
>>> 
>>>    According to "The Undocumented PC", the V20 did not support
>>> undocumented 80186 opcodes.  It also had a mode where it supported
>>> 8080 binary code.
>>> 
>>> Regards,
>>> 
>>> Steve N.
>>
>>I actually had some V30s on a few PCs (the V30 was to the 8086 what the
>>V20 was to the 8088). The V3x was significantly faster than the 808x on
>>multiply and divide, etc.
> 
>    Yes I had a Zenith Z-100 and swapped out the 8088 for a while with
> a V20.  It seemed to run 10 to 15 percent faster, on average .  It did
> not like the 8087 I put in, so I went back to the 8088.

I couldn't afford an 8087, so I stuck with the V30!



-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#161945 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

From"J. Clarke" <j.clarke.873638@gmail.com>
Date2016-04-03 20:20 -0400
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<MPG.316b7d3ea66d790698a079@news.eternal-september.org>
In reply to#161929
In article <dmdfkqFs66uU2@mid.individual.net>, news0006@eager.cx says...
> 
> On Sun, 03 Apr 2016 20:07:53 +0000, Steve wrote:
> 
> > Hi Bob,
> > 
> > Bob Eager <news0006@eager.cx> writes:
> >>On Sun, 03 Apr 2016 12:31:39 +0000, Steve wrote:
> >>
> >>> Hi,
> >>> 
> >>> Bob Eager <news0006@eager.cx> writes:
> >>>>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
> >>>>
> >>>>> NEC V20 - binary compatible with 80186
> >>>>
> >>>>That sort of depends on whether you limit yourself to the instruction
> >>>>set. The 80186 had a very different software interface to (e.g.) the
> >>>>interrupt controller.
> >>> 
> >>>    According to "The Undocumented PC", the V20 did not support
> >>> undocumented 80186 opcodes.  It also had a mode where it supported
> >>> 8080 binary code.
> >>> 
> >>> Regards,
> >>> 
> >>> Steve N.
> >>
> >>I actually had some V30s on a few PCs (the V30 was to the 8086 what the
> >>V20 was to the 8088). The V3x was significantly faster than the 808x on
> >>multiply and divide, etc.
> > 
> >    Yes I had a Zenith Z-100 and swapped out the 8088 for a while with
> > a V20.  It seemed to run 10 to 15 percent faster, on average .  It did
> > not like the 8087 I put in, so I went back to the 8088.
> 
> I couldn't afford an 8087, so I stuck with the V30!

Interesting--I didn't have an 8087 in my Zenith, but it worked fine in 
the Genuine IBM PC at work when I added a V20 (note--I _was_ the IT 
department in that company--no approvals needed except for the 
expenditure).



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#161944 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

From"J. Clarke" <j.clarke.873638@gmail.com>
Date2016-04-03 20:17 -0400
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<MPG.316b7cb038f251da98a078@news.eternal-september.org>
In reply to#161916
In article <dmd755Fs66uU1@mid.individual.net>, news0006@eager.cx says...
> 
> On Sun, 03 Apr 2016 12:31:39 +0000, Steve wrote:
> 
> > Hi,
> > 
> > Bob Eager <news0006@eager.cx> writes:
> >>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
> >>
> >>> NEC V20 - binary compatible with 80186
> >>
> >>That sort of depends on whether you limit yourself to the instruction
> >>set. The 80186 had a very different software interface to (e.g.) the
> >>interrupt controller.
> > 
> >    According to "The Undocumented PC", the V20 did not support
> > undocumented 80186 opcodes.  It also had a mode where it supported 8080
> > binary code.
> > 
> > Regards,
> > 
> > Steve N.
> 
> I actually had some V30s on a few PCs (the V30 was to the 8086 what the 
> V20 was to the 8088). The V3x was significantly faster than the 808x on 
> multiply and divide, etc.

I may still have a V30 machine upstairs (I know there are a couple with 
V20s but I don't recall for sure whether the V30 went in one of _my_ 
machines or a machine at work).

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#162011 — Re: OT: processor binary- or pin-compatibility, was [Re: Processor

Frompechter@pechter.dyndns.org (William Pechter)
Date2016-04-04 15:53 +0000
SubjectRe: OT: processor binary- or pin-compatibility, was [Re: Processor
Message-ID<ndu2l7$r14$1@pechter.eternal-september.org>
In reply to#161916
In article <dmd755Fs66uU1@mid.individual.net>,
Bob Eager  <news0006@eager.cx> wrote:
>On Sun, 03 Apr 2016 12:31:39 +0000, Steve wrote:
>
>> Hi,
>> 
>> Bob Eager <news0006@eager.cx> writes:
>>>On Fri, 01 Apr 2016 21:22:31 -0400, Rod Pemberton wrote:
>>>
>>>> NEC V20 - binary compatible with 80186
>>>
>>>That sort of depends on whether you limit yourself to the instruction
>>>set. The 80186 had a very different software interface to (e.g.) the
>>>interrupt controller.
>> 
>>    According to "The Undocumented PC", the V20 did not support
>> undocumented 80186 opcodes.  It also had a mode where it supported 8080
>> binary code.
>> 
>> Regards,
>> 
>> Steve N.
>
>I actually had some V30s on a few PCs (the V30 was to the 8086 what the 
>V20 was to the 8088). The V3x was significantly faster than the 808x on 
>multiply and divide, etc.
>
>
>
>-- 
>Using UNIX since v6 (1975)...
>
>Use the BIG mirror service in the UK:
> http://www.mirrorservice.org

I used the V30 in my AT&T 6300 (Olivetti M24?) and it was pretty amazing how
well the box compared with a 286 on many things...  Some instructions seemed
to be much faster and it wasn't half bad with Xenix-86 either.

Too bad that the they didn't do a 286 look alike as a swap into the AT Clone
motherboards with the V20/30 8080 instructions.

Bill


-- 
-- 
Digital had it then.  Don't you wish you could buy it now!
pechter-at-gmail.com  http://xkcd.com/705/

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#161827

Fromroger.ivie@gmail.com
Date2016-04-02 09:48 -0700
Message-ID<778fd0a8-337d-484a-914b-2738194ce577@googlegroups.com>
In reply to#161804
VAX NV5+ largely pin-compatible with Alpha 21064. There are some things that are configurable options for 21064 that are fixed on NV5+.
-- 
roger ivie
roger.ivie@gmail.com

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#162046 — Re: processor binary- or pin-compatibility, was [Re: Processor ISAs]

From"Charles Richmond" <numerist@aquaporin4.com>
Date2016-04-04 17:24 -0500
SubjectRe: processor binary- or pin-compatibility, was [Re: Processor ISAs]
Message-ID<ndupd5$5d1$1@dont-email.me>
In reply to#161804
"Rod Pemberton" <NoHaveNotOne@bcczxcfre.cmm> wrote in message 
news:20160401212231.1c439bc6@_...
>
>           [snip...]                 [snip...]                   [snip...]
>
> Z80 - binary compatible with 8080

The Z80 is *not* strictly "binary compatible" with the 8080.  There is some 
slight difference in the way the parity flag is used in some compare 
instructions, and also some incompatibility with the half-carry flag. 
Everywhere I look on the 'net, it seems people are trying to plow this 
knowledge under and ignore it.

-- 

numerist at aquaporin4 dot com

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#162052 — Re: processor binary- or pin-compatibility, was [Re: Processor ISAs]

FromBob Eager <news0006@eager.cx>
Date2016-04-04 23:08 +0000
SubjectRe: processor binary- or pin-compatibility, was [Re: Processor ISAs]
Message-ID<dmgafnFrjkoU3@mid.individual.net>
In reply to#162046
On Mon, 04 Apr 2016 17:24:28 -0500, Charles Richmond wrote:

> "Rod Pemberton" <NoHaveNotOne@bcczxcfre.cmm> wrote in message
> news:20160401212231.1c439bc6@_...
>>
>>           [snip...]                 [snip...]                  
>>           [snip...]
>>
>> Z80 - binary compatible with 8080
> 
> The Z80 is *not* strictly "binary compatible" with the 8080.  There is
> some slight difference in the way the parity flag is used in some
> compare instructions, and also some incompatibility with the half-carry
> flag. Everywhere I look on the 'net, it seems people are trying to plow
> this knowledge under and ignore it.

Very few things are 100% binary compatible. Even the 8088 was different 
to the 8086 - it was easy to write a program to tell them apart.




-- 
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
 http://www.mirrorservice.org

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#162100 — Re: processor binary- or pin-compatibility, was [Re: Processor ISAs]

FromCharlie Gibbs <cgibbs@kltpzyxm.invalid>
Date2016-04-05 03:05 +0000
SubjectRe: processor binary- or pin-compatibility, was [Re: Processor ISAs]
Message-ID<ndva17115nk@news6.newsguy.com>
In reply to#162046
On 2016-04-04, Charles Richmond <numerist@aquaporin4.com> wrote:

> "Rod Pemberton" <NoHaveNotOne@bcczxcfre.cmm> wrote in message 
> news:20160401212231.1c439bc6@_...
>
>>           [snip...]                 [snip...]                   [snip...]
>>
>> Z80 - binary compatible with 8080
>
> The Z80 is *not* strictly "binary compatible" with the 8080.  There is some 
> slight difference in the way the parity flag is used in some compare 
> instructions, and also some incompatibility with the half-carry flag. 

I remember reading about programs that would figure out which processor
they were running on...

> Everywhere I look on the 'net, it seems people are trying to plow this 
> knowledge under and ignore it.

"The worst thing about getting older is watching knowledge die."  -- me

-- 
/~\  cgibbs@kltpzyxm.invalid (Charlie Gibbs)
\ /  I'm really at ac.dekanfrus if you read it the right way.
 X   Top-posted messages will probably be ignored.  See RFC1855.
/ \  HTML will DEFINITELY be ignored.  Join the ASCII ribbon campaign!

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#162132 — Re: processor binary- or pin-compatibility, was [Re: Processor ISAs]

FromBogus@Embarq.com (Steve)
Date2016-04-05 17:43 +0000
SubjectRe: processor binary- or pin-compatibility, was [Re: Processor ISAs]
Message-ID<c1.2b8.3qfbn2$05r@NOVOSAD3.EMBARQ.COM>
In reply to#162046
Hi,

 "Charles Richmond" <numerist@aquaporin4.com> writes:
>"Rod Pemberton" <NoHaveNotOne@bcczxcfre.cmm> wrote in message 
>news:20160401212231.1c439bc6@_...
>>
>>           [snip...]                 [snip...]                   [snip...]
>>
>> Z80 - binary compatible with 8080
>
>The Z80 is *not* strictly "binary compatible" with the 8080.  There is some 
>slight difference in the way the parity flag is used in some compare 
>instructions, and also some incompatibility with the half-carry flag. 
>Everywhere I look on the 'net, it seems people are trying to plow this 
>knowledge under and ignore it.

   Well if the Z80 runs your 8080 operating system, editor,  games,
assembler, and other programs, perhaps it is compatible enough to
ignore the differences.  Or at least to forget about them.

Regards,

Steve N.

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#162141 — Re: processor binary- or pin-compatibility, was [Re: Processor ISAs]

FromAhem A Rivet's Shot <steveo@eircom.net>
Date2016-04-05 19:15 +0100
SubjectRe: processor binary- or pin-compatibility, was [Re: Processor ISAs]
Message-ID<20160405191505.3b9d78b93f580beed65481ac@eircom.net>
In reply to#162132
On Tue, 05 Apr 2016 17:43:34 GMT
Bogus@Embarq.com (Steve) wrote:

> Hi,
> 
>  "Charles Richmond" <numerist@aquaporin4.com> writes:
> >"Rod Pemberton" <NoHaveNotOne@bcczxcfre.cmm> wrote in message 
> >news:20160401212231.1c439bc6@_...
> >>
> >>           [snip...]                 [snip...]
> >> [snip...]
> >>
> >> Z80 - binary compatible with 8080
> >
> >The Z80 is *not* strictly "binary compatible" with the 8080.  There is
> >some slight difference in the way the parity flag is used in some
> >compare instructions, and also some incompatibility with the half-carry
> >flag. Everywhere I look on the 'net, it seems people are trying to plow
> >this knowledge under and ignore it.
> 
>    Well if the Z80 runs your 8080 operating system, editor,  games,
> assembler, and other programs, perhaps it is compatible enough to
> ignore the differences.  Or at least to forget about them.

	It was a rare program that depended on the difference, and anyone
sane wrote for the intersection knowing that there were a lot more Z80
machines than 8080 but you couldn't rule out the latter.

-- 
Steve O'Hara-Smith                          |   Directable Mirror Arrays
C:>WIN                                      | A better way to focus the sun
The computer obeys and wins.                |    licences available see
You lose and Bill collects.                 |    http://www.sohara.org/

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#162585 — Re: processor binary- or pin-compatibility, was [Re: Processor ISAs]

From"Charles Richmond" <numerist@aquaporin4.com>
Date2016-04-17 02:37 -0500
SubjectRe: processor binary- or pin-compatibility, was [Re: Processor ISAs]
Message-ID<nevea1$q9c$1@dont-email.me>
In reply to#162141
"Jon Elson" <jmelson@wustl.edu> wrote in message 
news:arWdnVu0vfUQZJLKnZ2dnUU7-fPNnZ2d@giganews.com...
> Ahem A Rivet's Shot wrote:
>
>
>> It was a rare program that depended on the difference, and anyone
>> sane wrote for the intersection knowing that there were a lot more Z80
>> machines than 8080 but you couldn't rule out the latter.
>>
> Subtle differences, maybe so.  But, the Z80 had a bunch of instructions to
> handle 16-bit address calculations that were very useful.  And there were
> the INIR and OUTIR (I think) opcodes that were almost DMA, but controlled 
> by
> the processor.  VERY handy for controlling various gear.  They put the CPU
> in a loop, moving some counted number of bytes from a sequence of memory
> locations to or from an I/O port.  You could do this at something like 
> half
> a MB/second.
>

Yes, and the Z80 added PC relative addressing and *two* index registers. 
But the discussion was compatibility.  The Z80 got rid of the need for a 12v 
power supply, and the 8085 did the same later for Intel.

-- 

numerist at aquaporin4 dot com

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