Re: Intel 8085 - interview?

[Eric Smith via cctalk]

On Fri, Feb 9, 2018 at 3:41 PM, Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:

> The V-series may be a good example of why Intel didn't want to publicize
> the added 8085 instructions.
>

Maybe. What I'd heard from multiple sources was that they only wanted the
8085 to replace the 8080, so it was supposed to be "better" in terms of
being a lower-cost 8080 replacement, needing fewer support chips (except an
address latch, but that's cheaper than an 8228/8238), but they didn't want
it to have a better instruction set that might put it into sockets that
might otherwise get filled with an 8086/8088.

Re: Intel 8085 - interview?

[Chuck Guzis via cctalk]

On 02/09/2018 01:59 PM, allison via cctalk wrote:

> I use that as an example of compatibility or extensions another more 
> familiar is the NEC V20 fits in the 8088 socket but has enhanced
> performance and native 8080 emulation mode.
The V-series may be a good example of why Intel didn't want to publicize
the added 8085 instructions.

Aside from 8080 emulation, the V-series also has some x86 "orphan"
instructions, such as the BCD string instructions that were never
carried over into any other x86 design.

It reminds me a bit of the 386 bit-string instructions that were
publicized early on, but never implemented AFAIK in any 80386.

--Chuck

Re: Intel 8085 - interview?

[allison via cctalk]

On 02/09/2018 04:18 PM, Sean Conner wrote:
> It was thus said that the Great allison via cctalk once stated:
>> The industry was loaded with that the 6502 series also had that going on
>> as well as the 6809 and others.
>   Do you have any information about undocumented opcodes for the 6809?  
>
>   -spc
Not a processor I use much bt there is a version of the 6809 that has
additional modes.
Thats the Hitachi 63b09 wich is 6809E compatable save for it has an
extended
mode and more registers.

I use that as an example of compatibility or extensions another more
familiar
is the NEC V20 fits in the 8088 socket but has enhanced performance and
native
8080 emulation mode.

Allison

Re: Intel 8085 - interview?

[Chuck Guzis via cctalk]

On 02/09/2018 12:26 PM, allison via cctalk wrote:

> IBM PC early also did that... other vendors of the 8088 didn't work
> in the 64K and early 256K IBM PCs due to a slight timing variation
> that reputedly intel helped design in.  One gate fixed it but it was
> undocumented thing you could getaway with only with Intel 8088s.

Hmm, must have been *very* early PCs, as mine had an AMD 8088 in it--but
wasn't AMD a licensee of the Intel part?   But then, so was NEC.

I think IMSAI used the "different" NEC 8080s in their floppy controller,
as they were inexpensive (because of the incompatibility) and in the
particular application, it didn't matter.

I do recall very early 8085s having a "reset" bug, necessitating some
external glue, but it's been too long for me to remember the details.

--Chuck

Re: Intel 8085 - interview?

[Sean Conner via cctalk]

It was thus said that the Great allison via cctalk once stated:
> 
> The industry was loaded with that the 6502 series also had that going on
> as well as the 6809 and others.

  Do you have any information about undocumented opcodes for the 6809?  

  -spc

Re: Intel 8085 - interview?

[Eric Smith via cctalk]

On Thu, Feb 8, 2018 at 9:56 PM, Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:

> On 02/08/2018 07:18 PM, Eric Smith via cctalk wrote:
> > At some point I read an article or a transcript of an interview with an
> > Intel employee (or former employee) who had been involved with the design
> > of the 8085, describing how he had specified additional instructions over
> > those of the 8080, and they had been implemented in the silicon, but then
> > the decision was made to not document any of the new instructions other
> > than RIM and SIM.
> >
> > I no longer recall which Intel employee that was, and can't find the
> > article or interview. Does anyone else remember that, and perhaps have a
> > copy?
>
> Do you mean Cort Allen?   His email a couple of years ago was:
>
> manofqu...@aol.com
>

That's not the interview I was thinking of, but it's definitely interesting!

Re: Intel 8085 - interview?

[Chuck Guzis via cctalk]

On 02/09/2018 10:57 AM, Warner Losh via cctalk wrote:

> For those that don't want to read through the entire datasheet,
> https://electronicerror.blogspot.com/2007/08/undocumented-flags-and-instructions.html
> has a good summary.

RIM and SIM were always documented for the 8085.   Not doing so would
have made it difficult to use the added features, such as "half" and
TRAP interrupts, in addition to bit-bang serial I/O.

In the Calmos document cited by Al, the discussion of added flags and
instructions begins on PDF page 39 and is much clearer.

--Chuck

Re: Intel 8085 - interview?

[Warner Losh via cctalk]

On Fri, Feb 9, 2018 at 11:29 AM, Al Kossow via cctalk  wrote:

>
>
> On 2/9/18 9:23 AM, Chuck Guzis via cctalk wrote:
>
> > Calmos (then later Tundra) Semiconductor actually documents them in
> > detail in their CA80C85 datasheet, but those were from the early 1980s.
>
>
> the info is still out there
> http://saxelec.com/doc/T8000.pdf


For those that don't want to read through the entire datasheet,
https://electronicerror.blogspot.com/2007/08/undocumented-flags-and-instructions.html
has a good summary.

Warner

Re: Intel 8085 - interview?

[Al Kossow via cctalk]

On 2/9/18 9:23 AM, Chuck Guzis via cctalk wrote:

> Calmos (then later Tundra) Semiconductor actually documents them in
> detail in their CA80C85 datasheet, but those were from the early 1980s.


the info is still out there
http://saxelec.com/doc/T8000.pdf

Re: Intel 8085 - interview?

[Chuck Guzis via cctalk]

On 02/09/2018 05:22 AM, allison via cctalk wrote:

> Also all of the competitors and second sources that made 8085s had the
> added instructions.  The are indeed handy too.

Calmos (then later Tundra) Semiconductor actually documents them in
detail in their CA80C85 datasheet, but those were from the early 1980s.
What was interesting was that even through we were working pretty
tightly with Intel in 1976, not a word of the added instructions was
uttered by our sales guy, "Fast Eddie", who usually was pretty well
informed about the goings on over in Santa Clara.   Bill Davidow was on
our BOD as well.

That's a shame; we could have used those instructions too.

--Chuck

Re: Intel 8085 - interview?

[allison via cctalk]

On 02/08/2018 11:56 PM, Chuck Guzis via cctalk wrote:
> On 02/08/2018 07:18 PM, Eric Smith via cctalk wrote:
>> At some point I read an article or a transcript of an interview with an
>> Intel employee (or former employee) who had been involved with the design
>> of the 8085, describing how he had specified additional instructions over
>> those of the 8080, and they had been implemented in the silicon, but then
>> the decision was made to not document any of the new instructions other
>> than RIM and SIM.
>>
>> I no longer recall which Intel employee that was, and can't find the
>> article or interview. Does anyone else remember that, and perhaps have a
>> copy?
> Do you mean Cort Allen?   His email a couple of years ago was:
>
> manofqu...@aol.com
>
> He wrote;
>
> Actually, all of these instructions were 100% tested when they were
> manufactured at Intel. The test program used to test these devices
> contained all of these instructions and was written to do an extensive
> test on ALL instructions in many combinations and order. So, unless the
> 8085 broke after it was shipped, these instructions were tested and were
> working.
>
> I know this because I was the Test Engineer at Intel that developed the
> 8085 Production Test Program. I wrote all the code for this test and it
> ran on a Megatest @8000 test system.
>

Also all of the competitors and second sources that made 8085s had the
added instructions.  The are indeed handy too.

Allison

Re: Intel 8085 - interview?

[Chuck Guzis via cctalk]

On 02/08/2018 07:18 PM, Eric Smith via cctalk wrote:
> At some point I read an article or a transcript of an interview with an
> Intel employee (or former employee) who had been involved with the design
> of the 8085, describing how he had specified additional instructions over
> those of the 8080, and they had been implemented in the silicon, but then
> the decision was made to not document any of the new instructions other
> than RIM and SIM.
> 
> I no longer recall which Intel employee that was, and can't find the
> article or interview. Does anyone else remember that, and perhaps have a
> copy?

Do you mean Cort Allen?   His email a couple of years ago was:

manofqu...@aol.com

He wrote;

Actually, all of these instructions were 100% tested when they were
manufactured at Intel. The test program used to test these devices
contained all of these instructions and was written to do an extensive
test on ALL instructions in many combinations and order. So, unless the
8085 broke after it was shipped, these instructions were tested and were
working.

I know this because I was the Test Engineer at Intel that developed the
8085 Production Test Program. I wrote all the code for this test and it
ran on a Megatest @8000 test system.