Is anyone interested with the Z80?

Did you know that the Z80 has different memory access timings for instruction fetches and standard memory accesses?

I worked at Mostek maintaining the Fairchild Sentry testers used to test the Z80s when they first began to manufacturer them. The second computer I every

built (parts, pcb, solder) was the SDB-80 which was the Mostek Software Development Board for the Z80 with 16K bytes (8 - MK4116 16K bit) dynamic RAMs

which Mostek also made. The first wire wrap board I ever made was a 48K byte dynamic RAM board also using MK4116s that worked with the SDB-80. I can

tell you there were a bunch of happy technicians when we were told that Mostek would be second sourcing the Z-80 and even happier when we were told we

could buy SDB-80 kits and build them ourselves! Those were really fun days. I still have a Zilog Z80 in a ceramic package that says it was manufactured in

Dallas even though Mostek was actually in Carrollton a suburb in Dallas County just north of north-west Dallas.

Wow! that's amazing that you got such a large DRAM board working with Wire-wrap.

Do you still have any photos or schematics of it?

It was quite rare to come across Mostek parts in Australia. We usually got Zilog, SGS and Sharp.

And from memory the SGS parts didn't support the undocumented instructions.

(addendum to audio discussion)

It would seem that I was not right after all in stating that various audio debates have become a thing of the past.

(while visiting him, my son pointed this out to me:)

- (as to the objectivists vs. subjectivists debate) a class-D* power amp has been presented at recent Munich High-End Show**,

   which is said to be "100% mathematically correct". The following statement, however, is the relevant one in our issue:

  "We build what we simulate and simulate what we build. ... We believe that all matters for the sound quality can be measured

   although we often have to develop new measurement methods that are indicative of the subjective sound quality. We direct

   all R&D efforts on such measurable metrics. If this does not agree with the listening results we improve our objective metrics."

   For all interested:  https://www.audioxpress.com/news/purifi-audio-promises-to-reduce-distortion-in-speakers-and-amplifiers  .

   For all not versed in audio who-is-who:  the people behind Purifi are leading developpers in their field.

- (as to the being there - at recording - experience) Dr. Edgar Choueiri, professor of applied physics at Princeton University,

   has developped a 3D audio processor, enabling the listener to enjoy his records in 3D via a normal stereo set: BACCH SP.

   All we can do is hope and pray that MS will leave this alone, to prevent it from suffering the same fate as HDCD ...

Ray

*for all not versed in audio: the D does not stand for digital; class D means switching amps.

**once again: HD Vinyl nowhere to be seen (heard), no news, no nothing - a hoax ... ?

COMPACT  wrote:

 

Take a look at this - I think it is impressive!

 

http://www.fagginfoundation.org/biography/

Sorry for this late response, COMPACT (seen too many doctors lately) !

Thanks for sharing this fascinating, illustrated time-line through the life and works of one of the key figures in (micro)computer history.

I knew most of the facts and figures, but getting everything presented from the horse's mouth really is something else.

From the many things that caught my eye, let me comment on a few:

- (1965) "The Olivetti Programma 101 ... contained a small computer made of discrete components ... ". However much my admiration for the

   development of the IC, I've never been able to commit myself to applying them in my designs, still (since the sixties) preferring hand-picked

   discrete components over 'black boxes'. That way I feel full freedom and more in control of things, although I'm aware of the drawbacks; so

   call me oldfashioned ...

- (1970) "The layout of the Z80-CPU. Handdrawn by Federico (by two thirds) ... ". "Those were the days !" - no CAD-CAM. Has anybody ever

  assessed the error rate in both cases ?

Having written this, I wonder: wouldn't we have been better off here, sticking to your original question and everything directly related, than

wandering off(-topic) to audio nirvana ... ?

Cheers

Ray

COMPACT  wrote:

 

Take a look at this - I think it is impressive!

 

http://www.fagginfoundation.org/biography/

Sorry for this late response, COMPACT (seen too many doctors lately) !

Thanks for sharing this fascinating, illustrated time-line through the life and works of one of the key figures in (micro)computer history.

I knew most of the facts and figures, but getting everything presented from the horse's mouth really is something else.

From the many things that caught my eye, let me comment on a few:

- (1965) "The Olivetti Programma 101 ... contained a small computer made of discrete components ... ". However much my admiration for the

   development of the IC, I've never been able to commit myself to applying them in my designs, still (since the sixties) preferring hand-picked

   discrete components over 'black boxes'. That way I feel full freedom and more in control of things, although I'm aware of the drawbacks; so

   call me oldfashioned ...

- (1970) "The layout of the Z80-CPU. Handdrawn by Federico (by two thirds) ... ". "Those were the days !" - no CAD-CAM. Has anybody ever

  assessed the error rate in both cases ?

Having written this, I wonder: wouldn't we have been better off here, sticking to your original question and everything directly related, than

wandering off(-topic) to audio nirvana ... ?

Cheers

Ray

(addendum to audio discussion)

It would seem that I was not right after all in stating that various audio debates have become a thing of the past.

(while visiting him, my son pointed this out to me:)

- (as to the objectivists vs. subjectivists debate) a class-D* power amp has been presented at recent Munich High-End Show**,

   which is said to be "100% mathematically correct". The following statement, however, is the relevant one in our issue:

  "We build what we simulate and simulate what we build. ... We believe that all matters for the sound quality can be measured

   although we often have to develop new measurement methods that are indicative of the subjective sound quality. We direct

   all R&D efforts on such measurable metrics. If this does not agree with the listening results we improve our objective metrics."

   For all interested:  https://www.audioxpress.com/news/purifi-audio-promises-to-reduce-distortion-in-speakers-and-amplifiers  .

   For all not versed in audio who-is-who:  the people behind Purifi are leading developpers in their field.

- (as to the being there - at recording - experience) Dr. Edgar Choueiri, professor of applied physics at Princeton University,

   has developped a 3D audio processor, enabling the listener to enjoy his records in 3D via a normal stereo set: BACCH SP.

   All we can do is hope and pray that MS will leave this alone, to prevent it from suffering the same fate as HDCD ...

Ray

*for all not versed in audio: the D does not stand for digital; class D means switching amps.

**once again: HD Vinyl nowhere to be seen (heard), no news, no nothing - a hoax ... ?