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PET "Fat 40" 4032 RAM expansion, 80-col & IDE mods, etc.

gsteemso

Experienced Member
Joined
Sep 28, 2008
Messages
80
Location
north of Seattle, USA
Hi all,

First, RAM expansion:

I have looked at various sites online; one even sells NOS 64K RAM upgrades for the 8032, albeit at a high enough price I'd rather try to build my own. Alas, the only expansion header pinouts I was able to find were for the 8296, with a confusing "differences table" to the older 8032 board. According to a site that discussed the four types of PET system board, mine is what that site called a "type 3b" — a modified 8032 board that could support either 40 or 80 columns, 40 in my case.

I have heard that it is possible to add some chips and change some jumpers around to make the 4032 into an 8032, but while I found some schematics describing which jumpers to change, I haven't found anything about what chips to add, or where.

I've also heard rumours of an internal IDE mod where someone put a hard drive in his PET. That'd be seriously cool if it's true. Anyone know more?

If I get all of these changes made it'd be a fun project to try and port GEOS to the PET, using the ersatz bitmap mode provided by the block characters. Woohoo, a 160x50-pixel screen! :¬)
 

sjgray

Experienced Member
Joined
Feb 3, 2009
Messages
467
Location
Markham, Ontario, Canada
Hi,

Zimmers has schematics for most PET boards. Look on your board and find the matching schematics to find which chips you need to add and which jumpers to change.

Not a lot of software will use that extra ram even if you do install it. But if you plan to write your own software that won't matter.

Commodore did produce a "High Speed Graphics" board for the PET machines. This used a Thompson GPU and came with it's own 32K ram. You could draw lines, circles and plot multi-size text with the routines in ROM on the board.
There were also bitmap boards from third-parties such as MTU.

The IDE interface is very simple. You only need a few chips. It's the firmware that would be difficult to make it accessable in the standard commodore way. There are a couple IDE interfaces available for the C64 but I'm not aware of any for the PET. There were S-100 adapters for the PET and disk interfaces in the old days. There are IEEE hard drives like the commodore 9060 and 9090, and some third-party drives. There is one on ebay uk right now.

Check out the "UltraPET Project" on my web site:
http://www.6502.org/users/sjgray/projects/ultrapet/index.html

It encompasses some of the ideas you mention.

Steve
 

sjgray

Experienced Member
Joined
Feb 3, 2009
Messages
467
Location
Markham, Ontario, Canada
Where can I get my hands on one of the MMU boards? Or the schematic?

-Matt

The MMU board was made by TPUG. Unfortunately, just recently, they sold the last three remaining boards. I inquired about the boards two years ago but nothing happened until recently and I still DIDN'T get a board.... I did get a scan of the board and I hope to make my own but I haven't had time to reverse-engineer the schematics yet.

You could contact TPUG but I'm not sure how much luck you will have. I know there were other people trying to reverse engineer the board but I don't know if or when that might be available. I will make some inquiries...

Steve
 

sjgray

Experienced Member
Joined
Feb 3, 2009
Messages
467
Location
Markham, Ontario, Canada
If I get all of these changes made it'd be a fun project to try and port GEOS to the PET, using the ersatz bitmap mode provided by the block characters. Woohoo, a 160x50-pixel screen! :¬)

You could also replace the character set ROM with a set containing all combinations of 2x4 blocks so you could make a 160x100 pixel screen. I suppose with expansion ram you could build a virtual screen of any size and have the real screen a window into it that could be scrolled around as needed...

Steve
 

MikeS

Veteran Member
Joined
Dec 23, 2005
Messages
7,493
Location
Toronto ON Canada
Hi all,

First, RAM expansion:

I have looked at various sites online; one even sells NOS 64K RAM upgrades for the 8032, albeit at a high enough price I'd rather try to build my own. Alas, the only expansion header pinouts I was able to find were for the 8296, with a confusing "differences table" to the older 8032 board. According to a site that discussed the four types of PET system board, mine is what that site called a "type 3b" — a modified 8032 board that could support either 40 or 80 columns, 40 in my case.

I have heard that it is possible to add some chips and change some jumpers around to make the 4032 into an 8032, but while I found some schematics describing which jumpers to change, I haven't found anything about what chips to add, or where.

I've also heard rumours of an internal IDE mod where someone put a hard drive in his PET. That'd be seriously cool if it's true. Anyone know more?

If I get all of these changes made it'd be a fun project to try and port GEOS to the PET, using the ersatz bitmap mode provided by the block characters. Woohoo, a 160x50-pixel screen! :¬)
I assume that by now you've found the pinout for the 40/8032 expansion port and the 5 chips you need to add to the 4032 (UC6&7-2114,UB6&7-LS244,UB8-LS373) and the different editor ROM.
I'm curious: where'd you find the info on the jumpers?
 

gsteemso

Experienced Member
Joined
Sep 28, 2008
Messages
80
Location
north of Seattle, USA
I assume that by now you've found the pinout for the 40/8032 expansion port and the 5 chips you need to add to the 4032 (UC6&7-2114,UB6&7-LS244,UB8-LS373) and the different editor ROM.
I'm curious: where'd you find the info on the jumpers?

Well, the board revision #3b schematics, wherever it was I found them (it was one of the major sites) showed the alternate positions of ALL the jumper pads on the board, including the ones controlling RAM size (8, 16 or 32 KiB). The only information I have found on anything else is what I presented above, so no, I haven’t found the data I need except in a cross-my-fingers-and-make-educated-guesses kind of way. If you know it, please refer me.

Thanks,
G.
 

billdeg

Technician
Joined
Nov 18, 2003
Messages
3,872
Location
Landenberg, PA USA
FYI

"The CBM 64K memory expansion board kit that converts the 8032 into an 8096 will also operate on the "FAT 40" 4032. The operation is the same as on the 8096."

Summarized from the Commodore Midwest Regional Staff Newsletter April 15, 1982



Bill
 

sjgray

Experienced Member
Joined
Feb 3, 2009
Messages
467
Location
Markham, Ontario, Canada
First, I assume you looked here to find you have a "3b" board:
http://www.6502.org/users/andre/petindex/boards.html

It notes that there were two revisions of this board, so perhaps you could tell us the actual assembly# of the board you have so we're all on the same page.

Second, I assume you've looked at the schematics at zimmers. Which one matches your board?:
http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/univ/index.html
or
http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/univ2/index.html


The memory expansion connector can be found on page 1 of the schematics.

Third, in order for 80 columns to work properly you will need a new editor ROM, which can be downloaded from here:
http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/index.html
Which one you need depends on your keyboard (N=normal, B=business) and which frequency you have (50 or 60). Most 4032's had "N" keyboards, and since you are in the US I will assume you have a 60 Hz machine.

Steve
 
Last edited:

gsteemso

Experienced Member
Joined
Sep 28, 2008
Messages
80
Location
north of Seattle, USA
First, I assume you looked here to find you have a "3b" board:
http://www.6502.org/users/andre/petindex/boards.html

Yeah, that was it! I knew it was somewhere major.

It notes that there were two revisions of this board, so perhaps you could tell us the actual assembly# of the board you have so we're all on the same page.

Hmm, good call. After considerable searching, I found the assembly number 8032080 on the identifier area of the board. This matches the diagram below:


Happily, the 8032080-07 picture matches my board exactly. Nice to have that nailed down.

The memory expansion connector can be found on page 1 of the schematics.

Wow, that's a bit bewildering. Informative though. Do you know where I can find stuff like timing information?

Third, in order for 80 columns to work properly you will need a new editor ROM, which can be downloaded from here:
http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/index.html
Which one you need depends on your keyboard (N=normal, B=business) and which frequency you have (50 or 60). Most 4032's had "N" keyboards, and since you are in the US I will assume you have a 60 Hz machine.

I do indeed. I figured I’d probably need a different ROM, but wasn’t going to worry too much about it until I sorted out the rest of the project.

Thanks again for your help,

G.
 

Keal

Member
Joined
Feb 27, 2007
Messages
11
You could also replace the character set ROM with a set containing all combinations of 2x4 blocks so you could make a 160x100 pixel screen. I suppose with expansion ram you could build a virtual screen of any size and have the real screen a window into it that could be scrolled around as needed...

Steve

Using REVERSE he could double that to 4x4 for even higher res.
 

hexsane

Experienced Member
Joined
Mar 4, 2009
Messages
385
Location
Omaha, NE USA
Third, in order for 80 columns to work properly you will need a new editor ROM, which can be downloaded from here:
http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/index.html
Which one you need depends on your keyboard (N=normal, B=business) and which frequency you have (50 or 60). Most 4032's had "N" keyboards, and since you are in the US I will assume you have a 60 Hz machine.

Steve

There isn't an edit-4-80-n ROM that I can see. Does anyone know where this ROM may be? TPUG did a series of articles in TORPET circa 1981/1982 about doing the fat 40 to 8032 conversion:
http://www.tpug.ca/archive/torpet/Torpet_Issue_7_Oct_1981.pdf
http://www.tpug.ca/archive/torpet/Torpet_Issue_8_January_1982.pdf

I'm in the process of doing this conversion. Am hoping someone already has the ROM so I don't have to hack one together myself (There is already enough hardware modifications to do!).

-Matt
 

sjgray

Experienced Member
Joined
Feb 3, 2009
Messages
467
Location
Markham, Ontario, Canada
There isn't an edit-4-80-n ROM that I can see. Does anyone know where this ROM may be? TPUG did a series of articles in TORPET circa 1981/1982 about doing the fat 40 to 8032 conversion:
http://www.tpug.ca/archive/torpet/Torpet_Issue_7_Oct_1981.pdf
http://www.tpug.ca/archive/torpet/Torpet_Issue_8_January_1982.pdf

I'm in the process of doing this conversion. Am hoping someone already has the ROM so I don't have to hack one together myself (There is already enough hardware modifications to do!).

-Matt

Hmm, I didn't realize some were missing. I don't know if that's because it doesn't exist, or has just not been located. I don't think one would be too hard to make, given the info in those TPUG articles.

It would be great for someone to do the conversion and document it with photos so others can benefit. When I get some time I plan on doing a conversion of my 8296 board and I think I will have the same issue with no 40-column rom available for it. I hope to investigate whether I could make a hardware/software solution to allow the machine to switch between 40 and 80 columns on the fly via print chr$(something) or sys call.

Steve
 

carlsson

Veteran Member
Joined
Jul 30, 2003
Messages
6,275
Location
Västerås, Sweden
Apart from any Fat 40 converted computers, would there ever have existed a 8000 series PET with the N keyboard? I think most of the ROM dumps origin from original production machines, and if this variant never was sold, likely nobody in recent time has a dump neither.
 

brain

Experienced Member
Joined
Apr 24, 2009
Messages
148
Location
Iowa, USA
The MMU board was made by TPUG. Unfortunately, just recently, they sold the last three remaining boards. I inquired about the boards two years ago but nothing happened until recently and I still DIDN'T get a board.... I did get a scan of the board and I hope to make my own but I haven't had time to reverse-engineer the schematics yet.

You could contact TPUG but I'm not sure how much luck you will have. I know there were other people trying to reverse engineer the board but I don't know if or when that might be available. I will make some inquiries...

Steve

Are you talking about the board that allows OS/9 to run on the SuperPET?

Jim
 

hexsane

Experienced Member
Joined
Mar 4, 2009
Messages
385
Location
Omaha, NE USA
I have almost completed the conversion on a Universal Board 2 and am running in 80 columns. The keyboard table isn't correct for the N type keyboard yet I'll have to debug it later today after some sleep (almost 6 AM). Shifting appears to work properly. I think there are additional keys on the business keyboard that I'll have to hardwire to some momentary switches but I expected that. I didn't have enough lighting when I did the before pictures so I'll only be able to publish the end results. I'll make the new ROM available for download when I've figured out what I did wrong with the table mapping.

-Matt
 
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