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.

Thanks for your explanation and friendly comment, Doug !

I will certainly share my story in this blog, but hope you don't mind me waiting a bit for COMPACT to react ?

Btw, I've always been intrigued by the Friends-Amis story in connection with Matsushita Corp., leading to the development of the HHC.

Although based on the 6502 microprocessor, the resemblance to the design of the SHARP PC-1500 (including bay with peripheral) is

striking. The idea behind it may have been original, but just assuming that Matsushita had no knowledge of the earlier presented SHARP

pocket seems a case of blind faith.

Apart from that, European companies, Olivetti and Nixdorf, should be included in stories about the history of the development from calculators

to handhelds i.m.o.

Cheers

Ray

You can create your own blog on any topic just by clicking on the "Create" button at the top of the page.

Threads like this Z80 topic just fade from view unless members keep adding anecdotes, so I think it is great to add stories directly to the thread, even if they are only peripherally related.

As a newbie to this forum, I'm afraid I don't quite understand.

I don't have my own blog, and was responding to an 'invitation' by COMPACT.

You could put a link here to your own blog, or put the story here. I can't speak for everyone but either would be fine with me.

Hi COMPACT,

May I add another PC-1500A project story in response to your earlier interest, and present that, assuming you have also read my posts to Shabaz ?

(It would be boring i.m.o. to tell intertwined stories to two forum members, as if they didn't read each others 'incoming' posts, wouldn't it ?)

This story unfolded in the aftermath of PC-1500A's demise - ending in the permafrost of Siberia ...

As the story hasn't anything to do per se with Z80, does it interest you, and would it be acceptable in this thread ?

Would appreciate hearing from you

Cheers

Ray

Hi Shabaz,

As Appendices at the end of the 276 page PC-1600 Tech Ref Manual I found mnemonics, op-codes, and what have you of both the SC- and the

LH-processor. Not my cup of thea, really ... But maybe someone else finds the clues, required to answer the question: was LH-5801/3 a Z80

derivative, or not ?

For me Chapter 7 is much more evocative, and it confirms my belief all along, that not only 'Ol Blue Eyes did everything "My Way" ...

It is quite impressive what Sharp has integrated on-chip*, next to the processor 'core' - this goes for the Z80A derivative, as well as for the LH.

I've called what they have packed into this pocketcomputer "no mean feat". If you look at the features, you can say that again:

- 3 microprocessors, two 8-bit main CPUs (one emulating the PC-1500A a.o.) + one 4-bit subprocessor (I/O)

- 3 x 36 kB ROM

- RS-232C I/F

- serial optical I/F, 38.4 kbaud

- analog input (ADC)

- automatic power off with external wake-up from peripheral

- floppy and RAM-disk options

- 60-pin fully programmable system/expansion bus output

- 2 memory module slots

Impressive ? Sure ! A joy to work with (as a programmer or a user) ? Not really ... And that's a shame.

PC-1600 has never been able to replace PC-1500A in the market, possibly because it became the victim of its own over-complexity ?

At the time (mid eighties and on) Sharp had already her organizer concept ready, later shared in the PDA concept with Apple (Newton),

and so probably didn't care too much ... (PC-12xx, 14xx, E200, and E500 series thriving)

Cheers

Ray

* a.o. the complete port processor, LH-5811, of PC-1500 in the SC main CPU

Hi Ray,

It could be derived from the Z80, I really cannot tell one way or another.

I used the Z80 a lot in the home 8-bit computer era with plenty of machine code (I had no assembler) but I cannot recall much apart from a few instructions and op-codes that won't seem to leave the brain : )

The embedded 8-bit stuff I encountered later was mostly Motorola based (6805 and 6811 particularly) and a few other manufacturers.

Hi Shabaz,

Further to the Z80 discussion in relation to the Sharp PC-1600: reading the Technical Reference Manual, answers to several questions can be

found:  http://pockemul.com/Documents/PC1600/PC1600TechnicalReference.pdf .

First of all, the main CPU, SC-7852, is a Z80A-clone. Second: Sharp specifies LH-5801/3 for what they call the subprocessor; so early production

probably was equipped with the 'old' PC-1500A CPU, which was then later on replaced by an upgraded version, the LH-5803.

After that the LH-58xx series was obviously discontinued, in favour of their SC family of micrprocessors - maybe to improve Z80(A)-compatibility.

The best - most comprehensive yet concise - overview: https://sharppocketcomputers.com/index.htm#basic . As an aside: It is remarkable that

after the 4-bit SC dual processor in Sharp's first pocketcomputer, the PC-121x had been succeeded by the 8-bit LHs, 4-bit SC-processors were

used again in later models.

Where the master-slave operation in the PC-1211 worked flawlessly, cooperation between the SC-Z80A and the LH-subprocessor more often than

not led to system instability, up to complete crashes.

The main disappointment with the PC-1600 however was its substandard (for Sharp at least !) LCD. Cramming this 4 times bigger display plus an

extra full size PCB, etc. into the same case as the PC-1500 however, is of course no mean feat ...

Maybe taking a glance at mnemonics and opcodes in the PC-1600 Tech Ref Manual can bring our decission nearer as to the LH-5801 was a Z80

derivative, or not. Memory allocation of the SC-Z80 surely differs considerably from that of the LH-5801, yet addressing range is equal (512 kB),

thanks to the flipflop registers in the LH; the SC seems having to do a lot of bank switching in large applications ...

Cheers

Ray

Hi Shabaz,

Very interesting musings about Z80 and possible 'mimicry' ... And thank you for the literature suggestions.

I believe having gotten some idea of Sharp policy in the dozen or so years I've made a living out of their products in many applications.

Do share your viewpoint that a lot of Japanese manufacturers of the time had more than enough innovation capability of their own, in order

not having to rely on copying; they did however clever- and selectively enter into strategic alliances and joint ventures.

I was appalled to learn that the company was recently taken over by Foxconn, of all the lousy manufacturers of today ...

The Japanese goverment should be ashamed for not having done anything to prevent this - the company that produced the unique amber

EL-displays for the Space Shuttle and where Philips had to buy all their LCD patents !

Back to the good ol' eighties and Sharp policy: I still feel the only explanation that makes sense for the model number, (LH-)5801, is as follows.

Next to their OEM production of Z80 clones - LH080, etc. - they wanted a proprietary microprocessor design for their indeed innovative line of

pocket computers. However they did not want to isolate these products too much from the brands and models that had become well-known

market leaders, in order to reach the broadest possible acceptance. So they devised the number 5800, with a wink to the 6800; but in order

to prevent the impression that they would suggest to make a predecessor, or down-graded version, they made the number their own by changing

it into 5801. Speculative ? Sure, but have I "entered into the realms of phantasy" ?

There was btw a LH-5803, which was meant to emulate the 1500 in its successor, the PC-1600 in order to attain full SW-compatibility. (It didn't

work 100% - much like my XP Pro overlay on Windows 10; this was probably also the reason for the PC-1600 being a less stable system than the trustworthy 1500).

Cheers

Ray

Hi COMPACT,

Sorry for my late response.

Thanks for your friendly reply, and for sharing your broad knowledge to fill-in some of the white spots in mine.

Further to the Nestlé project (and risking being thrown out by the moderator on account of wandering too much off topic ...): the 'poor'

PC-1500A had to communicate with 68000 processors in the Swiss units. When the info required to tackel this problem didn't come in time

to meet the project deadline, I decided to try and overcome the speed differences ... in BASIC (call me crazy). The only solution to get around

a formal handshake was applying probability calculation. It worked fine and reliable.

Reading the history of the Z80, it seems safe tot conclude that Sharp must have been (one of) the very first (1980/81) to produce a CMOS

derivative (?) with many on-chip extras. Just out of curiosity I've once tested the PC-1500A for power consumption (keep in mind that there

was also an I/O controller on board, the LH-5811). Battery life was specified as 300 hrs, i.e. with the usual unrealistic operational limitations.

So after a fortnight of continously running an endlessly repeated program with heavy duty calculations, that made as much use as possible

of display functions, and most of all of the BEEP option, I expected to find my PC-1500A 'dying'. But after more than 3 weeks only the LCD

contrast showed some signs of a nearing 'low battery' condition. Unfortunately I had to abort the experiment, simply because I needed the

pocket computer for my programming work.

The first assembler, as far as I know, was made by Rasso von Schlichtegroll, fairly soon after the PC-1500's introduction; later he developped

a successful line of system programs and tools under the RvS brand, eventually commercialized by the Holtkötter publishing firm.

Jumping to the present, recently produced emulators may be the best way to keep the PC-1500(A) alive (and leave curious young users

in awe). As to the limited storing capacity of RAM chips in those days: the LH-5811 has a direct adressing capability of 64 kB - nothing fancy;

but because of the PU and PV flipflop registers, the full addressing range was 512 kB. And would you believe it: in the early eighties a small

third party company, AMS in Germany on the Danish border, managed to pack this huge amount of storage inside the pocket computer !

I'm not sure if/how his maybe conflicted with an eventual RAM module in the bay for external memory ... Later they had their Gold Card

produced in Taiwan for the top models in Sharp's organizer line: 256 kB, while Sharp was still fiddling with 32/64 kB.

Didn't know the TI-84 was Z80-based; always wanted to have one, never got around to it ... The origin of my interest stems from the late

seventies, and was thus calculator-oriented. I could go now into the old AOS vs. RPN debate, but this would be a) off-topic, and b) maybe

not of interest to anybody in this group. Suffice it to say that It is useless to try and grasp Sharp's design concept for its pocket computers

without taking her EL-5100 scientific calculator into account.

Cheers

Ray

Hi COMPACT,

Sorry for my late response.

Thanks for your friendly reply, and for sharing your broad knowledge to fill-in some of the white spots in mine.

Further to the Nestlé project (and risking being thrown out by the moderator on account of wandering too much off topic ...): the 'poor'

PC-1500A had to communicate with 68000 processors in the Swiss units. When the info required to tackel this problem didn't come in time

to meet the project deadline, I decided to try and overcome the speed differences ... in BASIC (call me crazy). The only solution to get around

a formal handshake was applying probability calculation. It worked fine and reliable.

Reading the history of the Z80, it seems safe tot conclude that Sharp must have been (one of) the very first (1980/81) to produce a CMOS

derivative (?) with many on-chip extras. Just out of curiosity I've once tested the PC-1500A for power consumption (keep in mind that there

was also an I/O controller on board, the LH-5811). Battery life was specified as 300 hrs, i.e. with the usual unrealistic operational limitations.

So after a fortnight of continously running an endlessly repeated program with heavy duty calculations, that made as much use as possible

of display functions, and most of all of the BEEP option, I expected to find my PC-1500A 'dying'. But after more than 3 weeks only the LCD

contrast showed some signs of a nearing 'low battery' condition. Unfortunately I had to abort the experiment, simply because I needed the

pocket computer for my programming work.

The first assembler, as far as I know, was made by Rasso von Schlichtegroll, fairly soon after the PC-1500's introduction; later he developped

a successful line of system programs and tools under the RvS brand, eventually commercialized by the Holtkötter publishing firm.

Jumping to the present, recently produced emulators may be the best way to keep the PC-1500(A) alive (and leave curious young users

in awe). As to the limited storing capacity of RAM chips in those days: the LH-5811 has a direct adressing capability of 64 kB - nothing fancy;

but because of the PU and PV flipflop registers, the full addressing range was 512 kB. And would you believe it: in the early eighties a small

third party company, AMS in Germany on the Danish border, managed to pack this huge amount of storage inside the pocket computer !

I'm not sure if/how his maybe conflicted with an eventual RAM module in the bay for external memory ... Later they had their Gold Card

produced in Taiwan for the top models in Sharp's organizer line: 256 kB, while Sharp was still fiddling with 32/64 kB.

Didn't know the TI-84 was Z80-based; always wanted to have one, never got around to it ... The origin of my interest stems from the late

seventies, and was thus calculator-oriented. I could go now into the old AOS vs. RPN debate, but this would be a) off-topic, and b) maybe

not of interest to anybody in this group. Suffice it to say that It is useless to try and grasp Sharp's design concept for its pocket computers

without taking her EL-5100 scientific calculator into account.

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 ... ?

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

The questions you've raised are certainly worthwhile, albeit far from new ...

First of all, there is broad consensus, that audio is the art of reproducing sounds, recorded in one acoustic environment, in an other - usually totally

different. As a (recent) result, room acoustics have become a hot item; with DSP prices coming down, ever more components in the reproduction

chain - both amps and active speakers e.g. - are equipped with some form of electronic adaptation. While this may seem progress, oldtimer audio

buffs (like us ?) probably wonder, what has become of good (?) old tone controls, or - a bit more sophisticated - equalizers ? The 'tilt control' on the

QUAD 34 pre-amp, beloved in the eighties (and not much unlike RIAA equalization, COMPACT), springs to mind. DSP-based room-correction

circuitry is said to spare you fysical adjustments, like COMPACT described; I don't think I'm convinced.

As to equalizers, in the nineties we were allowed one afternoon to 'play' with the famous Cello Audio Palette, originally intended for studio-use, and

the wet dream of many an audiophile. Although we really had a great time at the circular controls of that gem, we had second thoughts afterwards:

had we not in fact been indulging ourselves in 'bettering' recordings of top-notch mastering engineers ? Who did we think we were ?! Our host had

'encoded' the favourite tracks on his discs with the letters of the controls and the corresponding numbers of the scale settings ... (audiot).

Live vs. recorded comparisons were popular in both the UK and USA during the fifties, aiming at answering the question: how close have we come

with HiFi ? It was reported frequently that even highly experienced audiences (regular concert visitors) sometimes had trouble discerning one from

the other. But this only works in the same room, with the speakers exactly positioned, where the instruments/vocalists were before (and everything

else also kept constant, preferably). So there's not much hope of ever bridging the gap from concert hall/studio to listening room ... And "Bringing

the concert hall to your living room" a bluddy (marketing) lie !

The 'being there (present)' experience /illusion is in fact the last frontier in high-end audio. When auditioning a Cello set with Martin Logan CLS,

a much more experienced audiophile commented: "Ah, this is precisely the sort of set that enables you to hear a fly fart on the rear wall of the

recording studio !". That made us think: are we chasing ultra resolution in sound reproduction, or is our real aim musical satisfaction ? It took some

time to cure ourselves of 'audiophilia nervosa', but we have since been enjoying our music via much more down-to-earth equipment.

Stereo is btw. as much an illusion (and this goes as well for 'glued-together-again' digital signal samples, in an attempt to mimic analog sound).

I believe, though, ultimately most people do not care that they are listening to illusions, nor how far off they are from reality - they've simply come

to like them !

I hope you see my point: this kind of discussions is in fact a thing of the past, and when repeated all the same, bound to be ... pointless.

"The whole audiophile experience is subjective."

That was exactly my point, aimed directly at Ray.  The problem with subjective interpretation of audio reproduction is

that it is always "in the ear of the beholder".

"and audiophiles are passionate of what constitutes a great sound"

They just can't explain in objective terms what constitutes that great sound. And there is clearly such a thing as being

too passionate. That is one reason why the ear of the beholder is not a good thing.

"The recorded sound may not be technically perfect but it sure does sound crisp and clear."

There are a few acoustic instruments that produce sound that is not crisp and clear, a muted horn is a good

example. Various kinds of distortion are widely used with electronic instruments and some of these also produce

sound that is not crisp and clear. Does a crisp and clear reproduction of these instruments constitute great sound?

It does not represent a faithful reproduction of the instrument's sound in the acoustic environment where it was

made (being there as you previously put it). And to me that faithful reproduction is what constitutes a "great sound".

It's just not possible to do, at least for now, no matter how much technology, subjective audiophile BS, or money

thrown at it.

The whole audiophile experience is subjective.

Our universe conspires to prevent perfect recording and playback and audiophiles are passionate of what constitutes a great sound.

I wish that some Astronauts would set up some speakers and microphones outside the International Space Station to see how well they work.

Here is one audiophile's take on things. Have a listen for 90 seconds.

The Australian company RODE is successful making microphones and associated paraphernalia. The recorded sound may not be technically perfect but it sure does sound crisp and clear.

Their latest offering is a wireless Lavalier microphone transmitter receiver combination for digital cameras. ("Go") which is very convenient.

Sorry but those are easily provable deficiencies in vinyl recordings/turntables.

COMPACTS claim that audiophiles want the sense of being there at the original recording is a classic example of subjective.

How do they have the slightest idea of what the acoustics were at the original recording without actually being there? How

do you objectively reproduce something you've never heard?

I do like your down-to-earth way of enjoying your music, COMPACT !

As audio advisors, we've always aimed at improving someone's music enjoyment for reasonable money. In the age of streaming, and what have you,

it's hard to pin-point that to a fixed amount, but in the nineties we felt, you could not expect the average customer to be willing to spend more than say

$ 5.000 on a decent player, amp, and pair of speakers (cable-mania was not yet wide-spread then). Of course, this statement immediately raises the

question: what is 'decent' ?

Objectively: equipment, apart from reliable and user-friendly, should be free of apparent flaws like hum/hiss, disturbing 'plops', or distortion levels that

were considered acceptable before the seventies. Furthermore limited performance is less of a problem than a lack of balance*.

Subjectively: equipment should raise the enjoyment level of the customer at least to 'content', but we were only really satisfied, when he reported

"having heard details in his music, he had never heard before", "discovering his music anew" - that sort of thing ... (one customer even declared:

"You have enriched my life" - he has become a friend). Best proof of having succeeded in improving matters came from the wife, though. If she made

a spot-on remark while removing the emptied coffee cups, we knew we had hit bull's eye. Why ? Because women just listen without any prejudice,

while men (audiophiles) are busy trying to hear what they have read ... ; sadly, didn't do much for the WAF (Wife Acceptance Factor).

Cheers

Ray

* that is a.o. why 2-way mini-monitors (not the Bose crap !) can be so very satisfying - certainly if they've been designed by Andrew Jones

P.S.: thank you for the Faggin-link, COMPACT - I'll dive into it

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

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

Hi COMPACT and Garry,

(Better late than never:) I'm sorry, if I have provoked replies that to me read like a kind of vinyl bashing ... won't go into that, because the

arguments are mostly too well-known to make a discussion in this day and age still worthwhile. I've been used to these arguments in audio

circles, but didn't expect them here, to be honest. And the worn-out objective vs. subjective discussion - culminating in head vs. heart ratings -

better be left alone, too, wouldn't you agree ?

Never mind; I was in fact just closing off some musings with an anecdote, but perhaps it would have been wise to present it with a bit more

context. Here that is yet.

The show was during the vinyl revival in the nineties, and we only had a speaker brand plus hi-grade vinyl at the time - all the rest was borrowed

from friendly colleague-importers. A high-grade CD-player was part of the demo set, but only used on request from our visitors. Btw, we didn't

do analog vs. digital comparisons.

The purpose of the shredded Mona Lisa poster was to show in a (simplified) pictorial manner, what digitizing is in essence. Apart from a good deal

of laughter, we als got recognition by colleagues referring visitors to our demo room. Only Philips was 'not amused' (and that was long before we

demoed the CD Clarifier the next year, thereby proving their slogan - "Perfect for Ever" - wrong; but that's an other story).

I also like to make an other point: as an importer of high-grade audio, I had to audition/listen to numerous gear/sets. With a few exceptions

the equipment was not 'my cup of tea', and I was pretty sure that I wouldn't be able to enjoy my music through it. Most of the time I tried to

imagine however, what enthralled the owner/seller. And by doing so, I often succeeded in 'hearing his point' ...

To prevent allegations that I'm living in the past, and that vinyl is obsolete, let me turn my eyes to the future* for a change: after virgin, HQ, and

Quiet Vinyl, vinyl lovers recently were treated to (the promise of) the Holy Vinyl Grail: HD-Vinyl. Multi millions have been invested in this project

that stems from the country where mr. Adolf H. was born, and that is frequently mixed up with your beloved 'Down Under', COMPACT. At the

risk of being judged too critical this time (and even because the concept is basically on digital), I think it's a mad men's scheme, and am certainly

not alone in that: https://www.analogplanet.com/content/hd-vinyl-exciting-concept-its-last-years-news .

Cheers

Ray

* the commercial product has been announced several times - yet have seen nothing so far ...

Hi COMPACT,

"Like oscilloscopes, sound should be sampled at about 5x or more than the desired maximum bandwidth", COMPACT wrote.

This ex-Tektronix test & calibration engineer couldn't agree more, but ... at the time of development, this was technically way out of reach for the

people working on e.g. the quadrophonic sound registration on vinyl, as well as those working on the Red Book standard.

Nowdays, cartridges with a frequency range of up to 50 kHz are available, serving people who have been convinced that they need super-tweeters

at the other end of their music reproduction chains ...

"And how does one get a speaker to playback perfect square waves?", COMPACT asked.

Peter Walker of QUAD Mfg fame came pretty close; in fact it was his ultimate way of testing (300 Hz) his almost single-handedly developped ESL

(Electrostatic LoudSpeaker; (fifties). Ever auditioned one ? You will never forget the listening experience ! We've also enjoyed Martin Logan's CLS

very much; of the electrodynamic units, Manger and Dynaudio probably have the best pulse responses. With ED speakers one tries to avoid square

waves because reproducing the top part would mean sending DC trough the poor unit(s), which very few would survive eventually. Furthermore,

audio is about reproducing natural sounds, not technical noises*; and music is the most complicated of sounds. Faithfully reproducing it means

getting the rise and fall right - these coïncide with the attaque of the musical instrument played, and the decay of the resulting sound. The most

demanding instrument attaque-wise, in terms of amplifier slew rate, turned out to be the harpsichord (& family), which is easy to understand once

you look at its playing mechanism. The same cousin who introduced me to electronics via his self-built Xtal receiver, made replicas of famous old

European harpsichords, together with his father (my godfather). I quickly grew to like the sound, that many audiophiles loathe. A possible cure might

be listening to the first chords of Bach's Italian Concerto in a harpsichord rendition (as it was meant to be) - it sings so much more that way than on

the piano ! (Try Glenn Gould's fifties recording vs. his almost anemiatic eighties registration by Sony).

(to be continued)

Ray

* I know, that same Peter Walker in an interview made a statement in relation to his ESLs that seems to argue otherwise ...