PET/CBM 3032: Trying to identify a graphics board from memory

[track18]

Hi everyone,
I'm trying to figure out what kind of hires graphics card the PET/CBM 3032 we used to have at school back in the early 80s was equipped with. I've done some research about PET graphics cards already (there seem to have been many more different types than I ever imagined!), but up to now, I haven't come across one with features that seem to match what I remember.
The most striking feature the graphics card in question exhibited was that it apparently generated hires graphics by re-defining characters. The more you drew things on the screen (using a kind of PLOT command that probably came with some card-specific ROM), the more characters lost their original appearance, but seemed to contain parts of your drawing instead. IIRC, there was also a new BASIC command (CHRDEF or similar) for re-defining arbitrary screen codes by supplying the 8 bit patterns making up the corresponding character.
Does this ring a bell? If so, please let me know!
Thanks and cheers -- track18

 

[daver2]

There were (unfortunately) so many different (and incompatible) add-ons for the PET.

It sounds like a programmable character generator (PCG) with an add-on toolkit ROM to extend the BASIC. But which one...

Dave

 

[dave_m]

Track18,
Are you the kind person that years ago once sent me a large package of German delicacies in return for an EPROM for an old Commodore PET?
-dav_m

 

[track18]

Track18,
Are you the kind person that years ago once sent me a large package of German delicacies in return for an EPROM for an old Commodore PET?
-dav_m

Yes, that's me! And the EPROM you sent me is still working flawlessly in my PET!
After a ten year hiatus (raising the kids somehow took over the top position in my priority list), I finally started delving into retro computing again last summer.
Nice to see you're still around!
Cheers -- track18

 

[track18]

It sounds like a programmable character generator (PCG) with an add-on toolkit ROM to extend the BASIC. But which one...

"Programmable character generator"... so that's what it's called! Wasn't aware of this term -- cool, this will probably help me with my investigations!
Thanx -- track18

 

[AndyG]

Wonder over to Steve Grays web page as he has a list of boards

http://cbmsteve.ca/petgraphics/index.html

If it is a programmable character Rom then probably the HAL PCG 6500. There is the supersoft HR 40 board for the 3032 and also the MTU board.

 

[AndyG]

The first two have been reverse engineered and can be built up if you want them.

 

[AndyG]

GitHub - InsaneDruid/SuperSede-HRx: A 100% compatible replica of the HR40, HR40B & HR80 graphics boards for the CBM PET lineup

A 100% compatible replica of the HR40, HR40B & HR80 graphics boards for the CBM PET lineup - InsaneDruid/SuperSede-HRx

github.com

GitHub - InsaneDruid/PCG-6500: A 100% compatible clone of the programmable character set generator and sound device CBM PET series computers.

A 100% compatible clone of the programmable character set generator and sound device CBM PET series computers. - InsaneDruid/PCG-6500

github.com

 

[track18]

Wonder over to Steve Grays web page as he has a list of boards

http://cbmsteve.ca/petgraphics/index.html

If it is a programmable character Rom then probably the HAL PCG 6500. There is the supersoft HR 40 board for the 3032 and also the MTU board.

Been there already multiple times, but nothing in the list seems to match exactly to what I remember.
The PCG-6500 came in a seperate box (there was certainly no such thing attached to our 3032), while the SuperSoft HR40 seems to require a CRTC (which shouldn't have been present in a 3032). The MTU board seems to offer a separate video mode for hires graphics, so it's not PCG based. And neither of these boards comes with a "real" BASIC extension.
I've also been through the lists at https://6502.org/users/andre/petindex/extensions.html and https://mikenaberezny.com/hardware/pet-cbm/, to no avail.

 

[track18]

GitHub - InsaneDruid/SuperSede-HRx: A 100% compatible replica of the HR40, HR40B & HR80 graphics boards for the CBM PET lineup

A 100% compatible replica of the HR40, HR40B & HR80 graphics boards for the CBM PET lineup - InsaneDruid/SuperSede-HRx

github.com

GitHub - InsaneDruid/PCG-6500: A 100% compatible clone of the programmable character set generator and sound device CBM PET series computers.

A 100% compatible clone of the programmable character set generator and sound device CBM PET series computers. - InsaneDruid/PCG-6500

github.com

Hang on -- there seems to be a non-CRTC version of the HR40 board... need to investigate...
Cheers -- track18

 

[track18]

@AndyG: Just realized you participated in the reverse engineering project at https://forum.classic-computing.de/forum/index.php?thread/28633-supersoft-hrx-versuch-eines-neubaus/

 

[AndyG]

@AndyG: Just realized you participated in the reverse engineering project at https://forum.classic-computing.de/forum/index.php?thread/28633-supersoft-hrx-versuch-eines-neubaus/

Yes that was fun…. Ported a missile command game for the hr-40 board also to show what could be done.

 

[AndyG]

Hang on -- there seems to be a non-CRTC version of the HR40 board... need to investigate...
Cheers -- track18

It’s an easy board to build - fiddly bit is the overlap adapter to the 2114 video ram … not something you have to do with the crtc versions.

 

[track18]

Yes that was fun…. Ported a missile command game for the hr-40 board also to show what could be done.

Yeah, saw that... amaze, amaze, amaze!
Cheers -- track18

 

[track18]

It’s an easy board to build - fiddly bit is the overlap adapter to the 2114 video ram … not something you have to do with the crtc versions.

I'm tempted, but what puts me off is the vast amount of extra wiring required for it... well, maybe someday.
Apart from that, it probably still isn't the board I'm trying to identify since 1) it doesn't re-define regular characters and 2) it's software isn't sporting a real BASIC extension.
Cheers -- track18

 

[AndyG]

I'm tempted, but what puts me off is the vast amount of extra wiring required for it... well, maybe someday.
Apart from that, it probably still isn't the board I'm trying to identify since 1) it doesn't re-define regular characters and 2) it's software isn't sporting a real BASIC extension.
Cheers -- track18

The software does have a real basic extension. It’s built into the last 2k of the edit rom. The user manual can be found on Mike Naberenzy’s page. I also have a version recompiled to run in ram.

Mike Naberezny – Supersoft Graphics Board

mikenaberezny.com

You can define your own character set - saved in ram or rom. It doesn’t work like the PCG-6500 but good nevertheless. You can draw the characters horizontally or vertically.

The wiring looks complicated but as long as you are methodical is fine. I am sure one of the forum members could help you (in classic-computing.de)

PS. You can also see what we got up to with the commodore hsg hi res board though needs a crtc PET

 

[track18]

The software does have a real basic extension. It’s built into the last 2k of the edit rom. The user manual can be found on Mike Naberenzy’s page. I also have a version recompiled to run in ram.

Yes, I've seen those documents already. However, interaction with the Graphix tools happens through SYS calls rather than new BASIC keywords -- this is not what I meant by "real BASIC extension".

PS. You can also see what we got up to with the commodore hsg hi res board though needs a crtc PET

I've browsed through that thread, too -- it's really amazing what you folks have accomplisched with re-building all these different graphics boards!
Cheers -- track18

 

[track18]

I actually managed to find the two (!) floppy disks that I had acquired back in my school days -- at the hefty price of (I believe) 7 DM apiece (approx. $4 - quite a chunk of my allowance...). Since I don't have a floppy drive for my PET (does anyone happen to have a spare one lying around...?), I used a C64, a 1541 drive, and a 1541 Ultimate II cartridge to convert the disks into disk images - at least, as far as they were still readable; unfortunately, one side of one disk made the 1541U2 freeze permanent during the read process.

Anyway, I did actually manage to recover two or three programs that appear to have utilized the graphics card I’m looking for. (Good heavens, what on earth was I thinking back then, naming programs things like "F", "X", "Q", "TESTI", "BUTZI", or "GULLY"?! ) While there wasn't anything that seemed to involve drawing lines, there was at least some code that took advantage of the card's capability for character redefinition. Or so I assume - without the corresponding BASIC extension, the tokens in the program listing naturally aren't being decoded back into their original keywords. However, a peek into a memory dump using a machine-language monitor did at least reveal the following tokens:

$E3 => oddly enough, this displays as POKE (which is actually $97), and it evidently stood for a command that took one number as an argument (looking at the source code, I see entries like POKE 0 or POKE 1). This was probalby some kind of initialzation/reset command for the graphics system.
$E5 => this resolves to PRINT (which is actually $99), and - judging by the program context and the 9 numerical arguments accompanying it, it stands for the CHRDEF (or similar) command.

Incidentally, the source code does indeed contain a SYS 36864 command immediately preceding the first use of these instructions. This is in line with what I think to remember as the activation sequence for the BASIC extension.

I don't really think all this will be of much help in identifying the board in question, but I wanted to mention it anyway, just for the sake of completeness.

Cheers — track18

 

[daver2]

Converting the SYS 36864 into hexadecimal gives $9000, which is the first of the option ROMs.

As you say, not very useful...

Dave

 

[track18]

Converting the SYS 36864 into hexadecimal gives $9000, which is the first of the option ROMs.

Yes, I know -- currently, I have a DOS wedge ROM at that location, and when I tried to run one of my old programs I always got the wege startup message befor it run into a syntax error due to the unknown tokens.
Cheers -- track18