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Re: RTL for Z8000 series CPU?
Chuck F.,

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I wish we could bring the same business necessity around again...
Engineers today have no options left - things get monopolised
faster than developed. It is a social rather than a technical problem,
not necessarily solvable in our lifetimes.
 Not that I disagree with you that engineers had more sense back then
to me a person using tools which do things he/she does not understand
in detail is a machine operator, not an engineer...


Dimiter Popoff               Transgalactic Instruments


Re: RTL for Z8000 series CPU?
ajcrm125 schrieb:
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ISAs are not protected under copyright law. (The ISA documents and the
CPU design are, but not the ISA)

The real pitfall are patents. As Peter noted all original pantents
should be invalid by now, but
- there might be some patents that Zilog filed that were only granted
many years later. These might be still alive. Check USPTO in that case.
Sometimes companies threaten people with patents that were granted, but
for which they stop paying patent fees years ago.
- even when building an old school uC you will likely use modern
concepts some of which might be patented by zilog or others.

Companies like to invoke trademarks and trade secrets in the context.
For the former just make sure that you do not use z8000 as the name of
your processor but use it only in a descriptive way. ("Executes z8000 ISA")
For the latter make sure, that you do not know any trade secrets from
zilog. E.g. that you have never signed an NDA for an z8000 errata sheet
or anything like that.

I would not worry too muc, but h I agree with Peter that it might be a
good idea to try to get zilog on board. They might like what you do and
provide you with advice, contacts, etc.

Kolja Sulimma

There is a story about a guy who built an Apple-I clone recently and got
sued by apple. When Steve Wozniak realized that he informed the guy that
he never signed off exclusive rights to apple.
Moral: Never believe a company that threatens you. Allways demand proof.

Re: RTL for Z8000 series CPU?
On Fri, 23 Dec 2005 18:20:15 GMT, "Monte Dalrymple"


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I often wonder how many products never got developed further because
of lost documents at companies. Also how many companies can truly
recover if somwhow they had to start from scratch with only their
documentation in config control.

  Anton Erasmus

Re: RTL for Z8000 series CPU?
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Believe it or not, adequate documentation and control predates the
use of computers by a considerable margin.  It involved such things
as file cabinets with suitably dimensioned drawers to hold original
drawings, prepared on paper and mylar, sometimes with India Ink,
the use of Ozalid machines, proper parts list, etc.

"If you want to post a followup via groups.google.com, don't use
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Re: RTL for Z8000 series CPU?

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Oh, the documentation existed, and it was in the control of Shima, the
designer. But once he left the company I don't know who, if anyone,
inherited his filing cabinet. It wasn't until much later that such design
materials were kept in a centralized location with a control number
and access/revision control. Even then, sometimes things went in to
DC never to be found again, so designers hated to give the original
stuff up to DC.


Re: RTL for Z8000 series CPU?
AMD received the transistor diagrams as part of the second-source
agreement, and they then reverse-engineered a logic diagram. (I know,
for I was involved).
AMD is a bigger, and perhaps more organized company.
But this is all some 27 years ago...
Peter Alfke
Monte Dalrymple wrote:
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Re: RTL for Z8000 series CPU?

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Interestingly, the classic drawing cabinet, to hold drawings hanging
from four fingers for easy access, is credited by some sources to ...
Charles Babbage.

- Brian

Re: RTL for Z8000 series CPU?
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Does anyone know anything about the Z80'000 that I've got a prelim
datasheet/usermanual for?  It seemed like a chip ahead of its time...


Re: RTL for Z8000 series CPU?
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The Z80 matched its time and became hugely popular. I don't
know about the Z8000, may be it remained not that popular
because it was ahead of its time (generally, products ot
people ahead of their time have the destiny of simply not being
by the majority of their time), and then may be it had to compete with
other designs, like the 68k etc. Well, the 8086 became popular
in spite of the 68k and the Z8000 can't possibly have been such
a mess as the 8086 was (is), so the reason(s) may have been completely
different, perhaps (likely, I believe) not technical at all.
 I hope Peter, Monte and perhaps others
who have been  involved could shed some light.
(I am also curious about the story, but I don't know the
Z8000 so I would appreciate an educated judjment).


Dimiter Popoff               Transgalactic Instruments


Re: RTL for Z8000 series CPU?

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The Z80,000 was after my time. So I have nothing to say about it.

The Z8000 appeared right after the 8086, and almost simultaneously with
the 68000 by Motorola, all 3 were 16-bit microprocessors. And the race
was on!

The 8086 won because IBM picked its baby-brother, the 8088, for the PC,
and because of Intel's massive marketing campaign ("operation Crush"),
against the cleaner and technically superior 68000. Never underestimate
Intel's marketing muscle. It was a brutal campaign. There is a book
about it, by Mr Davidov, the Intel marketing guy.

The Z8000 became condemned to a back-water existence. It was smaller
and simpler and thus potentially cheaper than the 68000, but (like the
8086) it partitioned the memory space into 64K segments, and there was
no way to detect when the address counter rolled over. Ziliog used
arrogant and semi-religious arguments for memory partitioning (the chip
architect really believed that it was a great feature, not a handicap),
but the upcoming graphics applications preferred a linear address
space, and they all went to the 68000.
The Z8000 was left with military and some arcade-game designs.
My only encounter with Steve Jobs was when I tried (unsuccessfully) to
convince him to use the Z8000 instead of the 68000 for what soon became
the Macintosh. The 68000 came in a gigantic package, and just its gold
plating cost almost as much as the Z8000 die. But the linear addressing

Of the three contenders, the obviously worst one became the winner. The
68000 did so-so, and the cleanest and leanest became the loser. Who
says life is fair?.
Peter Alfke, reminiscing.

Re: RTL for Z8000 series CPU?
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..Or Intel's manufacturing muscle - once the IBM PC selected the x88, it
really was Game Over, and helped a lot more by Microsoft's marketing
Muscle, than Intel's.

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~68000 is still alive, in Coldfire microcontrollers, but if the Z8000
had 64Kpages, it was too similar to the x86, and also too late to use
the code base the x86 then had.

  The Key in all this, is Intel was able to make, and ship x88 silicon,
while the others were sampling, and/or unable to meet price targets.

  There was also a time, back then, when better code size mattered
due to the price of memory.

  These days, the 64K issue appears again in the microcontroller sector-
most 16 bit cores naturally have 64K opcode reach issues - and we
see a swing into 32 bit microcontrollers : memory is far cheaper today.

  An interesting 'inversion' is the sight of a mere 8K code variant
ARM from Philips - LPC2101.


Re: RTL for Z8000 series CPU?
I was at Onyx Systems in 1980 doing the Unix V7 port for the machine
that spring to meet the NCC dedline at the begining of that summer. The
Z8002 had just finally became stable for a multitasking OS. We shipped
a few thousand of them before Carl Berg pulled the plug on the UNIX
management team wanting more MPM/CPM machines. Carl funded Onyx to sell
IMI 8" disk drives, another of his venture companies. While the Z8002
easily ran PDP-11 applications that were ported to it .... larger
address space applications developed for Vax, PDP10 & 20, and IBM main
frames suffered horribly due to the segmentation.

Motorola's M68K wasn't stable yet, but did become stable about a year
later while I was at Fortune Systems doing design work on that machine.
After years of living in segmented architectures and crippled address
spaces on small machines, the M68K was the first microprocessor that
would actually handle large address spaces cleanly to compete head on
with Dec Vax and PDP10 & 20 lines. Fortune took the 32:16 to Comdex in
the fall of 1981 and took best of show as the classy high performance
multiuser desktop UNIX box. IBM release the PC, at about 30% the
performance just weeks earlier with it's new OS .... PCDOS (soon to be
also sold by it's supplier as MSDOS).

While doing the M68K unix there was a LOT of pressure to find some Z80
CPM/MPM compatability and migration path for applications developed for
those platforms.

By late spring 1982 the demand to CPM/MPM compatability was completely
dead, as that market died in it's foot steps as IBM shipped more PC's
than all the Z80 machines that existed in 1982. Going to market with
the largest computer companies sales team competing against you is a
very tough sell.

Now the next part of the story is the part that very few people
understand ... and probably the most important part never to forget
.... and that is that ....

Re: RTL for Z8000 series CPU?
ok, sorry for the brief break ... in 1980 Wang was chewing up the
minicomputer office market with several machines that had the premier
word processing system in use in most large offices, especially the
legal office market.  Selectric typewriters had for a decade been the
machine of choice, as it's bail lock keyboard had THE TOUCH for speed
typists, as you quickly learned not to bottom keys, but release on fall
thru greatly reducing finger shock by not having to bottom keys or take
the recoil from the key hitting paper in your finger tips. The problem
was that these typewriters were expensive to buy, and due to high
maintence from the rotate tapes and complex timing they were much more
complex than the standard Royal or other common typewriter. Plus, they
were multi-pitch and multi-font adding a new look to business

Enter word processing, daisy wheel printers, and electronic document
storage and editing, and Wang had a gold mine, for about the cost of a
high end selectric.  IBM decided it had to compete in this new market,
and in the summer of 1980 release the Display Writer, a computer based
document system using the 8086 at a cost of about $8K for a single
station, and about $26K in the 3 station version. The story was that
IBM traded Intel bubble memory patents for the rights to the 8086 so
IBM could mfg it's own processor chips. During that same spring another
group in IBM was working on the PC, and decided to use the same
processor design, that they already had rights too.  So the Z8000,
which wasn't stable yet, really was never a contender ... nor the M68K
which wouldn't be stable for another year or so.

At this same time, high quality glass terminals, like the Datamedia
DT80, were roughly $2K list, and low end glass terminals like the
ADM-3A where just under a grand list. Similar prices for fully
configured Radio Shack TRS-80 systems, especially the TRS80 Model 2
which was the high end machine.

IBM releases the PC priced at just under $2K with dual floppies, with
PCDOS and inside a few months all the large Z80 programs are being
ported to the PC ... especially several key word processing
applications, which combined with a high end daisy wheel printer,
creates an affordable word processing solution at about the same price
as a good Selectric ... and a much cheaper maintence contract.

IBM killed two cash cows ... the selectric typewriter and the
Displaywriter without realizing what they had done. IBM sales was
giving away PC's with a huge institutional discount at just above
ADM-3A prices, which combined with 3270 emulation software, also
destroyed IBM's mainframe terminal business. By perchasing PC's in
volume, institutional and other large buyers, were able to ratchet down
IBM's multi-tiered pricing to get huge discount on IBM minicomputer and
mainframe products. As a result, thousands of PC's sat every where,
unopened, just to get huge prices savings on big ticket purchases. This
lead to discount grey market channels for PC's, and even lowered the
street price to accellerate the comdity PC word processing market.

Replacing over a decade of selectric typewriters, and several years of
high end Z80 business computers, with 16 bit processors took about 18
months during 1982 and early 1983, and then the market saturated. The
first huge computer tech buble ended with the tech crash in 1983. That
further fuelled depressed computer prices as a huge over production
inventory was liquidated at fire sale prices.

With the market very flat, depressed sales, depressed prices, it took
the industry the next two years to retool, reengineer, and come out of
that down turn with much better products that took another 5 years to
saturate the market as demand for word processing, business computers,
and home computers really became mainstream.

Re: RTL for Z8000 series CPU?

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And how many had an 8051 to interface a Selectric to a Centrnics port as a

Re: RTL for Z8000 series CPU?
On Wed, 4 Jan 2006 13:16:44 +0000 (UTC), "Bill Davy"

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I actually did my own design from scratch, complete with all the
careful testing with an oscilloscope of the reed relay signals in the
IBM electronic model 85 I was working on, using an 8051 to interface
it to a serial port.  Included both hardware and software handshaking
and buffers to handle the slow output rate of the typewriter.  Worked
first time, too!!  Used it for years as my printer, capable of
handling multi-part forms when needed.

I can't imagine how many folks did Selectric conversions -- it was
because of them (and my inability at the time to find a design
specifically for the electronic series that followed it) that I tried
my hand at the unit I owned.  I knew I should be able to get it
working and, sure enough, I did.  That was my very first design from
scratch of any significance in electronics.  I remember it well.


Re: RTL for Z8000 series CPU?
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Actually, I wrote that... :)


Re: RTL for Z8000 series CPU?

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The Z8000 just didn't happen to make into anything like the PC
or the Macintosh. IIRC, it was used in a fair bit of
industrial, telecom, and military gear.  I never used the Z80K,
and don't remember much about it other than it was a full
32-bit architecture with cache, a pipeline, and a paged MMU. (I
do remember seeing some datasheets).  It took Intel years
before they had anything even approaching the Z80K.

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The Z8000 was a very nice architecture.  Very PDP-11-like. Far,
far, better than that dog's-breakfast that Intel puked up and
named the 8086.  It had a nice large set of registers (16x16bit
registers that could also be used as 8x32 bit and I think
4x64bit). The instruction set was very regular (more so than
even the 68K). The Z8000 daisy-chained interrupt scheme was an
utter dream to work with compared to the nightmare that was the
8259 -- which was an obsolete piece of crap when it was
introduced in 1980 or whenever it was.  There's a very special
place in hell reserved for whoever put that bit of waste into
the IBM PC.  The Z8000 (like the Z80) included a built-in DRAM
refresh controller. The Z8000 also had some very nice
peripherals in the Z8036 counter/timer/PIO chip, the Z8030 dual
sync/async UART, the Z8010 MMU.  The Z8530 (the version of the
8030 with the muxed bus) is still widely used today.

IIRC, the Z8000 didn't have a version with an 8-bit external
bus like the 8088 or the 68008, so that limited it's
application in cost-senstive products.  The CPU and the
peripherals were all NMOS and were pretty high power (about
200mA each, IIRC).  That didn't help much.

Here's are a couple nice pages:

http://www.kranenborg.org/z8000 /

Apparently the Z8000 is still shipping in CMOS as the Z16C00

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Grant Edwards                   grante             Yow!  I just heard the
                                  at               SEVENTIES were over!! And
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Re: RTL for Z8000 series CPU?

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So why exactly would you want such a design? Do you have Z8000 binary
code you must run?

As noted below other IP shops have functionally reversed engineered it.
I recall one aerospace company had to run old code with timing
precision and paid for the Z8000 design to be redone. A functional
clone could give good guarantee that machine codes would run in same
time clock for clock. The Z8000 was complicated enough but was still a
fully predictable design as far as external events were concerned ie no

As it happens I also reverse engineered some of the Z8000 blocks around
79 and still have paper docs for the datapath, but that wouldn't get
you very far today. Also a good collection of comp arch books before
the H &P bandwagon took over, would often describe the
microarchitectures in some detail of most all mid 70s and earlier

If you don't need cycle accuracy, why not write a ISA translator and
retarget to Arm, x86, whatever. With the speed advantage you would get
a few orders of improvement. Thats probably already been done too!

transputer guy

Re: RTL for Z8000 series CPU?
I collect classic arcade games and am looking to do a remake of the
troublesome Pole Position boardset.  I then stumbled on this page:

and loved the idea.  The PPI and PPII boardsets are Z8000 based.

Re: RTL for Z8000 series CPU?
I looked at doing a conversion of the game, but the main problem is the CPU.
Having done most of the debugging work on the T80 core, which required
running a real cpu in parallel with the soft core and triggering the
analyser when they went separate ways - I can assure you it is a lot of work
to get it cycle accurate.

I am going to release the source of the Namco customs I have reverse
engineered some time soon, some of them are on the Pole Position board which
may help.


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