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Pet 2001-N, cost-effective ram /rom expansions?

I

Iainjh

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Joined
Feb 4, 2011
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37
Hello

I have a Uk pet 2001-N, 8k

I'd like to expand it to 32k, if there's an advantage in doing so. i have some interesting games and programs on my petdisk that I cant seem to run. I assume thats as I only have 8k and I am very limited in what I can run?

Also, it has a few empty rom sockets I'd like to play with adding few roms.. because ...well, why not? :)

it has 8k of 4016 rams and an empty set of IC positions, but all are filled in /don't have holes for sockets (see pics)

photo (3).JPG

image.jpg

photo 4.jpg

whats the best/ cheapest option to expand to 32k? (Sorry, I cant justify the cost of the no-doubt-excellent petvet)

I assume it has 2.0 roms. Which other roms can i fit in the 2 empty sockets ?

cheers in advance for any advice. ps see pics!

Iain
 
Yes you have the 2.0 basic ROM.

*** COMMODORE BASIC *** = 1.0
### COMMODORE BASIC ### = 2.0

a PetVet is a good product; however, if you don't want to buy it, you would build the Nicolas Welte's RAM/ROM expansion: http://vic-20.de/x1541/hardware/petram.html
it works fine for all 6502 commodore machines (including Vic20 and 1541 drive) and allow you to expand your machine up to 32 kB.

-- Giovi
 
Excellent, thank you!!

I have emailed him and hope he has a board to sell. thanks again.

re roms, if anyone has any links or suggestions, please advise

:):)
 
Hello Iain

The cheapest way to upgrade it is to rip out all those RAM chips in Bank 1, fit sockets to both banks and plug in a set of 16 4116 RAM chips.

You also need to reconfigure the funny looking jumpers to the right of the ROM sockets (they appear to be DIP switches but aren't).

It's not too difficult if you are reasonably comfortable with a soldering iron / solder sucker.

As it happens, I just ordered a large batch of 4116 DRAM chips from the States and will be selling on the ones I don't use. I'm in a similar boat to you, except mine's a 3016 which I seem to have damaged during the upgrade (my fault, I got impatient and ripped the RAM out with a heat gun... silly... there's another thread on here about that if you want to review my stupid story).

I would have gone for a PetVet myself, but as you say it is costly and your PET won't be original (it's down to personal preference what you feel about that). I also like the idea of doing the upgrade myself, even if I have botched it - hopefully my board is not beyond repair!

Regards

JonB

PS, I'm going to guess that you are also on the *. forum with the same handle. Me too...
 
ROM: exactly what you expect to do? Those empty socket are for firmware in location $9000 and $A000; they were often used for copy protection dongles. Of course you can write your own software, but afaik there aren't a lot of ROM images available: take a look on Zimmers, http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/other/index.html

About Nicolas: many years ago I bought one of these boards and it worth the money I spent! He also made a little mod with a jumper, so I can use it in PET and VIC-20 mode, or 1541 mode.

However recently I wrote to Nicolas and he didn't answer me. But the project is open source; so, as last resource, you can always contact one of those facilities that build PCB for you, if you can't build it by yourself: take a look on eBay. Also, on eBay you will find all the parts you need, in case you can't find in your local shop.

If you need some advise about how to use it or how to program the flashRom, write me a PM. I also have images ready for 2001/8, 3032, 8032 and VIC20, simply burn and forget, just ask if you need and I will mail them to you.

--Giovi
 
Iainjh said:
I'd like to expand it to 32k, if there's an advantage in doing so. i have some interesting games and programs on my petdisk that I cant seem to run. I assume thats as I only have 8k and I am very limited in what I can run?
Click to expand...

Some older games may only run on the BASIC 1 systems.

Also, it has a few empty rom sockets I'd like to play with adding few roms.. because ...well, why not? :)
Click to expand...

You seem to have something already in socket UD5. Try to execute sys 45056 and see if anything happens. You can put an EPROM in that socket called BASIC Programmer's Toolkit that is useful.
See http://zimmers.net/anonftp/pub/cbm/firmware/computers/pet/other/toolkit-b000.txt for info. That page also has the binary file.
 
Thank you all

I shall poke tonight and report back. If there are holes under those pads then that's perhaps the preferred route- if that's all I have to do, if there's no logic changes or other changes I'll get some rams!

And jobn, yes that's me, I lurk there as well! I saw your post, I do hope you can get it working. One thing you may want to consider , if you need it, speak to thecorfiot on sth. He's a very handy chap and may be able to fix it. He got two pets going at the weekend .. I have also just read a thread by a certain roland, I wonder if it's the same one from *.

I'll send you a message once I decide if I want to do the rams that way or get a board made.

Thank you again, more later!

:)
 
Iainjh said:
Hello

I have a Uk pet 2001-N, 8k

I'd like to expand it to 32k, if there's an advantage in doing so. i have some interesting games and programs on my petdisk that I cant seem to run. I assume thats as I only have 8k and I am very limited in what I can run?

it has 8k of 4016 rams and an empty set of IC positions, but all are filled in /don't have holes for sockets (see pics)
Click to expand...

Check the RAM size jumpers; if it really has 4016s you may actually have 16KB.

For a cheap RAM upgrade I'd think you could probably just disable the existing RAM altogether and put a 32K RAM chip into one of the ROM sockets with a jumper or two to redirect the chip enable and R/W signals.

You could also upgrade to BASIC4, which would take up one of those ROM sockets.
 
JonB said:
Hi Mike,
Which 3k RAM chip would fit? I may have to do this as a last resort for my 3016...
Click to expand...
Keep in mind that I don't have a 3016 and have never tried this, but it seems pretty straightforward in theory ;-)

Any one of several .600" 28 pin DIP 32KB SRAMs should work, e.g.:
http://www.futurlec.com/Memory/62256.shtml

Since it has 28 pins you'd have to make a small adapter; a pair of IC sockets would do. All the pins except four (18, 20, 21 and 24) line up, so you'd only have to separate those four pins, plug the 28 pin socket into the 24 pin, and connect them and the added /WE and three extra address lines to the appropriate places.

Any of the PET experts want to comment and point out the obvious flaw that I've probably overlooked? ;-)

Edit: I have done something similar to replace all the ROMs in a 2001-8 with one of Jim Brain's 6540<>27xx adapters and one 27256 containing both versions 1 and 2 (3?) BASIC; a little simpler because it's a ROM, but complicated by having to exclude the E800 I/O area.
 
Last edited:
Hi, SYS 45056 reports

(c) 1979 PAICS

which google seems to confirm is the programmers toolkit you mention, thanks!

which socket is it in? i have UD3 and UD4 empty.

I do have a couple of spare 32k srams (62256 and 58256, 32k static ram), is there a precise guide what to do to fit that in a socket ? and how to disable the present on board ram?

cheers!! :)

EDIT it definitely has 8 x 4106's, can someone please attach a photo of that ram-size jumper block so i may check? Mine looks a mess, someone surely has messed it up... Might explain why its only working as 8k.
 
Last edited:
There are two "shunts" as they are called on the board that set the memory configuration; one is 6 way, the other is 10 way.

Take a look at this thread : http://www.vintage-computer.com/vcforum/showthread.php?41167-PET-3016-memory-upgrade

Giovi (user giobbi) posted the (attached) diagram which shows the correct shunt settings for different memory configurations. They are the same as the ones on the schematic on zimmers. Actually, I'm thinking of taking my shunts out and wiring links on the board - it would look much neater. I've had to modify them from 16k as 16 x 4108 DRAMs to 16k as 8 x 4116 DRAMs and although it is electrically correct, the shunts do look a bit crap.

Cheers

JonB

PS, Good news on the toolkit. Very useful with a "bit o'BASIC", I'm sure!
 

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Iainjh said:
Hi, SYS 45056 reports

(c) 1979 PAICS

which google seems to confirm is the programmers toolkit you mention, thanks!

which socket is it in? i have UD3 and UD4 empty.

I do have a couple of spare 32k srams (62256 and 58256, 32k static ram), is there a precise guide what to do to fit that in a socket ? and how to disable the present on board ram?

cheers!! :)

EDIT it definitely has 8 x 4106's, can someone please attach a photo of that ram-size jumper block so i may check? Mine looks a mess, someone surely has messed it up... Might explain why its only working as 8k.
Click to expand...

Iain,
Be careful with these shunts. You might go from 8K to 0K. Remember most games work properly with 8K. With power off, use an ohmmeter to check continuity of the jumpers. They should be set for the 16K configuration. If jumpers are OK, then you might have bad RAM in second row. If you are not good at soldering, think twice before trying to unsolder the chips.

There is a trick called "piggybacking" that you might try one at a time on the chips in the second row to identify a bad chip before unsoldering any of them.

The Palo Alto IC ROM called BASIC Programmer's toolkit is in the UD5 socket which is the 4K address space B000-BFFF. Have you found the proper schematic page for the ROMs?
 
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