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.

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,

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 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

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.

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 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.

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

Hi COMPACT and Doug,

While the PC-1600 just didn't take off in the second half of the eighties, Sharp out of the blue discontinued the whole PC-1500A line. Among the

large number of commercial users worldwide with business application programs, one company especially had a huge practical problem with that:

Allianz, Germany's largest insurance company. They had abt. 50.000 (no typo !) PC-1500A systems for their commercial field service - now to be

written off just like that !

An other, very small, German company, having invested heavily in a rather unique application, decided, they could perhaps ensure continuity by

purchasing several dozen used systems from Allianz. Thus in the aftermath of the PC-1500A era a remarkable opportunity presented itself for us

(i.e. me and my son). Weilekes also was a father & son operation, who had devised a corrosion testing system for oil and gas pipes, to be used

in Siberia. The PC-1500A system was choosen because of its virtual indestructability and reliability in harsh environments. If anything, the mate

to the pocket computer - in fact a tiny 4-color plotter with system I/F - had to be overhauled meticulously. And that's where we came in.

My son (15 at the time) had already done so with several of these cigarette-pack size little gems*. Next the NiCad pack had to be exchanged for

a 'real' Sanyo (ask any model 'copter builder !). PC-1500A got a new keyboard switch mat, and any worn-out keys were replaced**. Refurbishing

further included all connectors, scratched LCD windows - sometimes complete cases were replaced.

Together with the Weilekes custom unit, the pocket computer + plotter were built into a special sort of cradle that the user wore like a candy seller

in a movie theatre; except this one had to shield the equipment from Siberian climate ... Sensors connected to the cradle were used for the actual

measurements. I believe these were basically resistance measurements - not surprisingly, taking into account the prominent position of German

developpers in skin resistance measuring medical devices.

What puzzles me now (was'nt aware of this then): both the former Soviet Union, and Hungary produced their own PC-1500A clone at the time;

wasn't Gazprom aware, or didn't they care ...?

Cheers

Ray

*of the Japanese ALPS brand, these days famous a.o. for its high-end audio-grade potentiometers

**Sharp spare part sets with only the [SPACE] and [ENTER] keys came in very handy indeed

I like your posts. They're fascinating!!

I wholly agree!

I wholly agree!

Hi Andrew,

Reading your profile, several thoughts spring to mind:

- seems like a wonderfulfilling (language economy) job/passtime - educating people, in order to enrich nowdays' ict with an intriguing past

- visiting my wife's family in Canada years ago, we went to the Toronto Science Museum - I had the time of my life !

- your level denominator goes, well ... lovely with your 'job' -:)  Women's role in technology is grossly underrated, and almost neglected

  (ENIAC, NASA, etc).

Cheers

Ray