CBM900 to SVGA monitor

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CBM900 to SVGA monitor

Michał Pleban
Hello!

As a part of restoring the CBM900 machine to life, I will need to
provide adequate display for it. Since it has the hi-res card, a trivial
MDA monitor will not work.

Here's the info I gathered so far about the card:

* The output has TTL levels for sync, but ECL levels for video data.
This was presumably typical of high-resolution workstations of that era
(Sun, Apollo etc). Actually the whole card is built with TTL chips, and
TTL-to-ECL converter is placed just before the video signal goes to the
connector.

* Vertical refresh is 60 Hz (negative polarity), and horizontal refresh
is 53.7 kHz (positive polarity). This means 895 scanlines, which makes
the advertised resolution of 1024x800 very plausible.

* The above parameters and resolution mean that the video clock would be
somewhere around 64 MHz. A strange thing is that the card does not
contain such oscillator (actually no oscillator at all) and I have no
idea how that frequency would be derived from the system clock of 12 MHz
(some kind of PLL?).

* Surprisingly, there is no 8563 chip in the card. The whole card is
built around TTL chips: http://imgur.com/kIgNsHi

There are several 16V8 chips on sockets, and the big chip is a 82S105
PLA. There are no ASIC chip at all. Presumably this means that the card
is simply a dumb framebuffer.

* There is 128 kB of RAM on the card, which corresponds to the presumed
1024x800 mono resolution. The connector pinout in the documentation
describes an "ECL+ Intensity" pin, but this is clearly an error as there
is no corresponding "ECL- Intensity" pin, and additional intensity
attribute would not fit in the supplied RAM.

My idea is to build a simple converter to connect a multisync SVGA
monitor. The obstacle I am currently facing is how to convert the video
to VGA level. I would probably not bother in converting ECL back to TTL
for that purpose, instead I will route the TTL vide to an unused pin in
the connector.

However I need a way to properly convert TTL levels of 0V/5V to VGA
levels of 0V/1V. I am afraid that a simple resistor voltage reducer
would be too slow to work in the 64 MHz range. This is an area where I
have no expertise so I would appreciate some suggestions.

Regards,
Michau.




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RE: CBM900 to SVGA monitor

Baltissen, GJPAA (Ruud)
Hallo Michał,


> However I need a way to properly convert TTL levels of 0V/5V to VGA levels of 0V/1V.

IMHO three options:


>  I am afraid that a simple resistor voltage reducer would be too slow to work in the 64 MHz range.

As being the simplest option, just try it. Maybe a bad image but IMHO it should proof that you're on the right way.


Second option: fast OC buffers with resistors tied to 1V.

Third option: build your own totempole outputs using fast transistors and diodes.

Just my two groszy :)


With kind regards / met vriendelijke groet, Ruud Baltissen
www.Baltissen.org


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Re: CBM900 to SVGA monitor

Michał Pleban
Hello!

Baltissen, GJPAA (Ruud) wrote:

> Second option: fast OC buffers with resistors tied to 1V.

Oh well. Why didn't I think of that! Big thanks :-)

Regards,
Michau.


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Re: CBM900 to SVGA monitor

Gerrit Heitsch
In reply to this post by Michał Pleban
>
> * Surprisingly, there is no 8563 chip in the card. The whole card is
> built around TTL chips: http://imgur.com/kIgNsHi

Well, the 8563 is the incarnation of the VDC with the 6502 bus
interface. And while they said that the VDC was designed for the CBM900,
I haven't been able to find out if they ever had working silicon or were
only in the design stages as it the 900 canceled.

Also, the VDC will only handle up to 64KB while your card does more.

Is there a way you could post a picture of the mainboard of the system?
If possible, with the writings on the ICs being readable. :)

  Gerrit



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Re: CBM900 to SVGA monitor

smf
This might not be the commodore 900 that it was designed for, supposedly
there were three projects.

1. Didn't get anywhere after having a lot of time and money poured into it.
2. Disappeared along with schematics etc when Jack left and shortly
afterwards the ST prototypes appeared. After Commodore sued Atari for
walking out with intellectual property, jack found the Atari 1850XLD
contract and sued Amiga (now commodore) for breaching that (separate issue
from the loan Atari gave to Amiga which is the story that was going round).
Both cases were settled out of court.
3. George Robbins and Bob Raible did the one that everyone knows while
commodore were wondering what they should be doing. The answer turned out to
be buying the Amiga so it got cancelled. Some machines made it out for early
Amiga software development using cross assemblers/compilers until native
tools existed, which is why "so many" are still around.


I got the impression the 8563 came out of the failed project and might have
been disregarded by George & Bob.

http://www.floodgap.com/retrobits/ckb/secret/900.html

"The Z-Machine guys (in two generations; the first designers, having failed,
turned development over to the second team of George Robbins and Bob Raible
[Dave Haynie]), were paragons of lunacy according to Bil Herd; the only
things to survive from that project, besides the 8563 (the 8563 is a story
in futility in itself; its misadventures in the 128's development cycle are
in the entry for the D128), were a strange disk controller that asked for
the desired sector and cylinder on every access (though Joe Forster/STA
points out that IBM mainframes do much the same thing for disk access as a
way of facilitating multitasking), and a legendary practical joke where the
900's engineers stole the furniture from the Commodore office lobby and made
their own lounge disguised as a VAX repair depot."


Two variants of commodore 900 were planned, but I'm not convinced that the
server version would have had an 8563 in it. My guess is you either bought
the workstation version with a built in graphics card (which the specs are
too high for an 8563), or you bought the server version that had no display
hardware & they only ever planned on using the 8563 in a dumb terminal.

http://www.floodgap.com/retrobits/ckb/secret/900.html

"Graphics and Sound Two versions, according to Peter Kittel; the graphics
version was 1024x800 monochrome (72Hz refresh on the monitor) and intended
as a workstation; the server variant was character display only. Graphics
powered by the 8563 VDC."

"According to Jim Brain, the 8563 (designed as a colour 6845; it became the
128's 80-column video chip) was intended and designed for the 900s, but of
course the 8563 has plenty of applications beyond that. In fact, an fragment
of an E-mail I ran across from Dave Haynie mentioned that the 8563, in tow
with a sidecar CPU (undoubtedly a 6502 in some form) and ACIA (6551?), was
to be the centrepiece of cheap multi-user terminals set up around the CBM
900 -- no less than glorified 6502-based Xterms. Clever! The article Anthony
furnishes above also mentions an integrated terminal, which may or may not
be the same thing, but it does talk about an optional multi-user card with
eight additional RS-232 ports which was undoubtedly the core of this idea.
Whether this card got finished is another story altogether. "


The history is pretty vague, it was a long time ago and the survivors appear
to have spent most of that period in a bar getting drunk. I doubt they
expected there would be a test thirty years later.

-----Original Message-----
From: Gerrit Heitsch
Sent: Thursday, July 24, 2014 7:59 PM
To: [hidden email]
Subject: Re: CBM900 to SVGA monitor

>
> * Surprisingly, there is no 8563 chip in the card. The whole card is
> built around TTL chips: http://imgur.com/kIgNsHi

Well, the 8563 is the incarnation of the VDC with the 6502 bus
interface. And while they said that the VDC was designed for the CBM900,
I haven't been able to find out if they ever had working silicon or were
only in the design stages as it the 900 canceled.


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Re: CBM900 to SVGA monitor

Uffe Jakobsen
Administrator


On 2014-07-24 21:48, smf wrote:

> This might not be the commodore 900 that it was designed for, supposedly
> there were three projects.
>
> 1. Didn't get anywhere after having a lot of time and money poured into it.
> 2. Disappeared along with schematics etc when Jack left and shortly
> afterwards the ST prototypes appeared. After Commodore sued Atari for
> walking out with intellectual property, jack found the Atari 1850XLD
> contract and sued Amiga (now commodore) for breaching that (separate
> issue from the loan Atari gave to Amiga which is the story that was
> going round). Both cases were settled out of court.
> 3. George Robbins and Bob Raible did the one that everyone knows while
> commodore were wondering what they should be doing. The answer turned
> out to be buying the Amiga so it got cancelled. Some machines made it
> out for early Amiga software development using cross
> assemblers/compilers until native tools existed, which is why "so many"
> are still around.
>

This may be a language barrier problem (in my end - so bear with me) :-)
- but what do you mean with the saying "why so many (CBM C900's) are
still around" - is it irony or ?

To my knowledge - we the CBM community as a whole - only know of about 6
unique CBM C900 systems that still exist today. There may be more
systems around - but these are the ones that we know of. And that is -
as far as I know - a much smaller number than the number of C65
prototypes that are known to exist today. Which makes C900 more rare
than C65.

Also where do you have the information that CBM C900's were used as
cross development systems for the Amiga ? In my mind the timeframe does
not quite fit - and I've never heard of that before.

On the contrary - as far as I know - a single Sage (II) systems was used
for the whole Amiga development prior to Commodores acquisition of
Amiga. After the acquisition they switched to Sun workstations. Plenty
of sources within Commodore have confirmed this. The SunOS PCC compiler
from Bell Labs is mentioned in Amiga ROM Kernel Reference Manual from
Commodore - other references to Sun exists in other manuals and writings
as well at the downloader program on an early WorkBench.

Kind regards Uffe :-)







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Re: CBM900 to SVGA monitor

Uffe Jakobsen
Administrator
In reply to this post by Gerrit Heitsch


On 2014-07-24 20:59, Gerrit Heitsch wrote:
>
> Is there a way you could post a picture of the mainboard of the system?
> If possible, with the writings on the ICs being readable. :)
>

@Gerrit: here you can find our pictures and reverse engineering info
based on our CBM C900 system - currently the only system that is known
to boot and run Coherent 0.7.3.

http://datamuseum.dk/wiki/Commodore/CBM900/Technical_Info
http://datamuseum.dk/wiki/Commodore/CBM900

http://datamuseum.dk/foto/20111117?page=1
http://datamuseum.dk/foto/20111117?page=2
http://datamuseum.dk/foto/20111117?page=3
http://datamuseum.dk/foto/20111117?page=4
http://datamuseum.dk/foto/20111117?page=5
http://datamuseum.dk/foto/20111117?page=6

I should mention that our CBM C900 system has the LowRes mezzanine
graphics card - which makes it a server with 4 RS232 serial interfaces -
and not like Michau's workstation system that has the HiRes mezzanine
graphics card.

Kind regards Uffe :-)



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Re: CBM900 to SVGA monitor

Michał Pleban
In reply to this post by Gerrit Heitsch
Hello!

Gerrit Heitsch wrote:

> Is there a way you could post a picture of the mainboard of the system?
> If possible, with the writings on the ICs being readable. :)

I have only this photo from my phone, will post more when I'm back from
vacation:

http://imgur.com/MPcy4Q1

Note that this must be an earlier revision of the mainboard that Uffe's,
because the keyboard interface is piggybacked on a small PCB in the CIO
socket, whereas in Uffe's computer it is alread included on the motherboard.

Regards,
Michau.

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Re: CBM900 to SVGA monitor

Michał Pleban
In reply to this post by smf
Hello!

smf wrote:

> http://www.floodgap.com/retrobits/ckb/secret/900.html
> "Graphics and Sound Two versions, according to Peter Kittel; the
> graphics version was 1024x800 monochrome (72Hz refresh on the monitor)
> and intended as a workstation; the server variant was character display
> only. Graphics powered by the 8563 VDC."

As we can see, this is wrong: workstation is not powered by the VDC, and
the refresh rate is 60 Hz not 72 Hz :-)

Regards,
Michau.

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Re: CBM900 to SVGA monitor

Gerrit Heitsch
On 07/25/2014 09:03 AM, Michał Pleban wrote:

> Hello!
>
> smf wrote:
>
>> http://www.floodgap.com/retrobits/ckb/secret/900.html
>> "Graphics and Sound Two versions, according to Peter Kittel; the
>> graphics version was 1024x800 monochrome (72Hz refresh on the monitor)
>> and intended as a workstation; the server variant was character display
>> only. Graphics powered by the 8563 VDC."
>
> As we can see, this is wrong: workstation is not powered by the VDC, and
> the refresh rate is 60 Hz not 72 Hz :-)

Also, what is the maximum refresh rate and resolution the VDC can
produce? The clock is 16 MHz and you have 64 KB display RAM max (as far
as I know).

That doesn't really let you do much. At least not 640 x 400 in 60 Hz,
unless you go interlaced.

  Gerrit





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Re: CBM900 to SVGA monitor

smf
In reply to this post by Uffe Jakobsen
>Also where do you have the information that CBM C900's were used as
>cross development systems for the Amiga ? In my mind the timeframe does
>not quite fit - and I've never heard of that before.

Third party application development, not operating system development.


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Re: CBM900 to SVGA monitor

smf
In reply to this post by Michał Pleban
>> and intended as a workstation; the server variant was character display
>> only. Graphics powered by the 8563 VDC."

>As we can see, this is wrong: workstation is not powered by the VDC, and
>the refresh rate is 60 Hz not 72 Hz :-)

I was assuming the "Graphics powered by the 8563 VDC" referred to "the
server variant was character display only." & not the workstation board,
because they were talking about building 8563 graphics terminals. Like all
the history it's pretty vague when you drill down to details.


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Re: CBM900 to SVGA monitor

smf
In reply to this post by Uffe Jakobsen
>To my knowledge - we the CBM community as a whole - only know of about 6
>unique CBM C900 systems that still exist today. There may be more systems
>around - but these are the ones that we know of.

Some say 200

https://groups.google.com/forum/#!msg/comp.sys.amiga.misc/zKaOc3wdgAU/5dNXLJN6pWIJ

Some say 500

http://www.floodgap.com/retrobits/ckb/secret/900.html

"Eventual Fate Scrapped prototype; project officially discontinued in favour
of the newly-acquired Lorraine, later becoming the Amiga. Some models,
however, were released in Europe as development systems at around US$4000
apiece (!), even though the actual computer was never publicly released. 500
units produced."


I've just looked and not found anything specific that expands on
"development systems". I may have assumed it meant for developing Amiga
software, but I thought I'd seen something before.


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Re: CBM900 to SVGA monitor

smf
In reply to this post by Uffe Jakobsen
>And that is - as far as I know - a much smaller number than the number of
>C65 prototypes that are known to exist today. Which makes C900 more rare
>than C65.

I don't think you can compare C65 and commodore 900.

The commodore 900 was a boring unix workstation that was slow and had very
little ram. The users will likely have been people who bought it to do a job
30 years ago and it stopped being useful a few years later. When that
happened the majority of them will have been thrown away.

The commodore C65 was a mysterious thing that got cancelled and then bought
up in a liquidation sale after commodore went under and heavily advertised
in magazines that people who loved commodore were still reading. They were
bought purely for their unique charm, I'd expect the majority (if not all of
them) to survive.


Whether something survives is pretty random.

http://www.rebol.com/article/0491.html

"I should mention that the main reason I was keeping most of this was for
prior-art computer HW/SW patent proofs (because Amiga and CDTV were ahead of
the curve.)"

Plenty of interesting equipment ended up being destroyed or in the back of a
cupboard, or hoarded by someone who doesn't want you to know they have it.


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Re: CBM900 to SVGA monitor

Uffe Jakobsen
Administrator
In reply to this post by smf


On 2014-07-26 19:47, smf wrote:

>> To my knowledge - we the CBM community as a whole - only know of about
>> 6 unique CBM C900 systems that still exist today. There may be more
>> systems around - but these are the ones that we know of.
>
> Some say 200
>
> https://groups.google.com/forum/#!msg/comp.sys.amiga.misc/zKaOc3wdgAU/5dNXLJN6pWIJ
>
>
> Some say 500
>
> http://www.floodgap.com/retrobits/ckb/secret/900.html
>
> "Eventual Fate Scrapped prototype; project officially discontinued in
> favour of the newly-acquired Lorraine, later becoming the Amiga. Some
> models, however, were released in Europe as development systems at
> around US$4000 apiece (!), even though the actual computer was never
> publicly released. 500 units produced."
>

I've never found anything that would indicate that they were sold in the
way described above - anyone ?


Quiting a former Commodore employee who contributed this information
about our CBM C900:

"
Commodore built this prototype UNIX workstation/server computer in the
same time frame as the Amiga and their PC-Clone and then decided that
they only had production capacity for two out of three, and the CBM900 lost.

All the approx 300-500 prototypes were recalled for destruction, but due
to some kind of "mistake" this particular machine, which was on loan to
a favored customer in Denmark, never made it back.

The machine resurfaced when this company cleaned up their basement, and
sent 3 euro-pallets of Commodore artifacts our way.
"

Reference:
http://datamuseum.dk/wiki/Commodore/CBM900

>
> I've just looked and not found anything specific that expands on
> "development systems". I may have assumed it meant for developing Amiga
> software, but I thought I'd seen something before.
>

Ok - I just interested in getting the history right

/Uffe




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Re: CBM900 to SVGA monitor

smf
>All the approx 300-500 prototypes were recalled for destruction, but due to
>some kind of "mistake" this particular machine, which was on loan to a
>favored customer in Denmark, never made it back.

I don't know, commodore are pretty well known for dumping their cancelled
projects in europe (like the C116).
It seems commodore germany doesn't like to throw stuff away & would rather
sell it.


https://groups.google.com/forum/#!msg/comp.sys.amiga.misc/zKaOc3wdgAU/oVq1JAy47K8J

Francois Rouaix

30/01/1992

>> In article <[hidden email]>, [hidden email]
(Joseph Korczynski) writes:
   J> Here some interesting information I found in October 1985
   J> Commodore MICROCOMPUTERS. I wonder what ever became of this product?
   J> A picture is also shown. The case looks very similar to the A2000
style.

   J> Commodore recently announced plans to market the Commodore 900, a
   J> multi-user, multi-tasking, Unix-compatible business system that can
   J> support up to eight work stations.
   [....]

I have one (tty only version, no bitmap). Now don't ask me how I got it.
The machine was displayed  at French SICOB in 1985. A member of the
C900 team told me that around 200 prototypes were built (in Germany,
hence the similarity with the A2000 case). Actually there is (or there
was) a C900 user group in Germany. Are you still there guys (Ralph, Richard
?).
I intended to use the C900 and its 4 serial ports as a multiplexer
for a BBS, but found out the machine was not reliable enough.
But the german folks actually wrote some stuff for the machine. Wow.
Anyway, it's history now, but a niece piece for a collector !
--Francois
PS: more details available on request ;-)




-----Original Message-----
From: Uffe Jakobsen
Sent: Sunday, July 27, 2014 12:56 AM
To: [hidden email]
Subject: Re: CBM900 to SVGA monitor



On 2014-07-26 19:47, smf wrote:

>> To my knowledge - we the CBM community as a whole - only know of about
>> 6 unique CBM C900 systems that still exist today. There may be more
>> systems around - but these are the ones that we know of.
>
> Some say 200
>
> https://groups.google.com/forum/#!msg/comp.sys.amiga.misc/zKaOc3wdgAU/5dNXLJN6pWIJ
>
>
> Some say 500
>
> http://www.floodgap.com/retrobits/ckb/secret/900.html
>
> "Eventual Fate Scrapped prototype; project officially discontinued in
> favour of the newly-acquired Lorraine, later becoming the Amiga. Some
> models, however, were released in Europe as development systems at
> around US$4000 apiece (!), even though the actual computer was never
> publicly released. 500 units produced."
>

I've never found anything that would indicate that they were sold in the
way described above - anyone ?


Quiting a former Commodore employee who contributed this information
about our CBM C900:

"
Commodore built this prototype UNIX workstation/server computer in the
same time frame as the Amiga and their PC-Clone and then decided that
they only had production capacity for two out of three, and the CBM900 lost.

All the approx 300-500 prototypes were recalled for destruction, but due
to some kind of "mistake" this particular machine, which was on loan to
a favored customer in Denmark, never made it back.

The machine resurfaced when this company cleaned up their basement, and
sent 3 euro-pallets of Commodore artifacts our way.
"

Reference:
http://datamuseum.dk/wiki/Commodore/CBM900

>
> I've just looked and not found anything specific that expands on
> "development systems". I may have assumed it meant for developing Amiga
> software, but I thought I'd seen something before.
>

Ok - I just interested in getting the history right

/Uffe




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Re: CBM900 to SVGA monitor

Michał Pleban
In reply to this post by Michał Pleban
Hello!

Michał Pleban wrote:

> However I need a way to properly convert TTL levels of 0V/5V to VGA
> levels of 0V/1V. I am afraid that a simple resistor voltage reducer
> would be too slow to work in the 64 MHz range. This is an area where I
> have no expertise so I would appreciate some suggestions.

Answering my own question: a simple resistor voltage divider at the
output of a 74S08 does the job perfectly, and creates a clear picture on
the LCD monitor :-)

Regards,
Michau.


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