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CBM (PET) 2001-8-BS

dave_m

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Interesting, thanks.

Is the software for the DOS wedge a file that just gets loaded randomly on the SD card as an isolated file, or does it have to be in some sort of folder or directory to work ?
Hugo,
The wedge is a tiny assembly program that installs itself at the top of BASIC memory. It puts a 'wedge' in the routine that looks at the commands entered from the keyboard. If it does not see a "@" or other special characters at the start, it simply lets the routine go on normally, but if it see the "@" character, it executes that shortcut command then returns to BASIC.

You should have the wedge program anywhere in the root directory of the SD card. You have to execute it only once with the load command LOAD"wedge",8 and run it. It will load itself into high BASIC and adjust the Top of BASIC pointer to protect itself. It is similar to a 'Terminate and Stay Resident' program in Microsoft DOS. The old wedge program has been around since day one at Commodore, but you should use the one referenced by the SD2PET page in case it has refinements needed to support subdirectories and image files although I imagine the code for that is in the SD2PET gadget. Do you have the full list of wedge shortcut commands? They are useful except for BASIC 4 users who have the 'Directory' and other commands which are just as good, well except for the subdirectory commands.
-dave_m
 

Hugo Holden

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daver2

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Hugo,

Nope, that's all there is to it. LOAD "WEDGE",8 and RUN - and then you get the additional functionality (as implemented by the wedge and described on page 2) for free.

The 'nice' commands are '/' and '^' to "load" or "load and run" a program with the minimum of typing!

As Dave stated, you can have subdirectories to keep games and whatever in to save having a load of individual files at the root directory level.

Dave
 

Hugo Holden

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I'm working on the VDU, I will post a separate thread about the VDU's later.

I had an interesting problem/quirk which required fixing. I noticed with my VDU I could not reduce the brightness to a satisfactory level, even at min on the control, the text was too bright. Looking at the early PET VDU schematics, it appears that the early ones used a 9VALP4 or a 9VAMP4 white phosphor CRT. My board is the early board version, but the CRT is the green MW24-302GH. It is not the phosphor color of course causing this effect, but it appears these two gun's in these two CRT's have a different beam cutoff voltage.

The voltage documented on the schematics for the CRT's grid bias supply suggest that the beam cutoff voltage for the 9VALP4 is probably around 30V but its 45V for the MW24-302GH. A practical test confirms this with the MW CRT at least, as the beam cuts off at around -47 to -48V grid volts when the cathode is at zero volts.

The negative supply voltage for the CRT's grid is derived from a separate winding on the H output transformer (LOPT). It appears that the LOPT's might have been a little different between VDU versions.

I don't have the 9VALP4 to test though.

Is it widely known that all the early PET's had white screens and the later ones green or was it just pot luck what the customer got ?

The circuit is interesting in that the video output stage (driving the CRT's cathode) is "digital" in that the cathode voltage is forced from a high value (causes beam cutoff) and then hard to zero for the text/graphics signal, and there is no contrast control, or analog level control there and the beam brightness you end up with, at zero cathode volts, is then set by the negative grid bias where the brightness control circuit resides.

I pondered how to remedy this problem in my VDU, with minimal modifications, so I could control the CRT brightness down to a low level near beam cutoff . I tend to run all my CRT's (scopes too) with the min beam brightness for comfortable viewing as it is kinder to the phosphor and gives better focus normally). I solved it by placing 8 turns of wire around the LOPT core and placing that in series with the LOPT winding generating the grid bias voltage (correct phasing) to increase the negative voltage supply to around 48V for the brightness control circuit. Now the brightness control range is much better. I will add the details of this when I do up an article on the VDU. But I have no idea if anyone else has ever seen this problem, it might be unique to my VDU with the particular board and CRT combination.
 
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Hugo Holden

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Here is something else that is odd:

If I didn't know any better I would swear that the case of my PET, with the brass inserts in the plastic being 2BA threads and the VDU having the same thread screws, in addition some of the parts resembling Philips resistors, the Euro designation CRT MW24-302-GH I would swear at least some those parts of it were manufactured in the UK or manufactured for UK assembly. For example BA thread screws are as rare as Rocking Horse manure in the USA, a friend has being trying to get some. Even Allied, which is the USA's RS components outlet, don't carry them (removed them from the stock line) so he had to get them in a clandestine manner from RS Components in Mexico. Interesting that the VDU's original electrolytic capacitors are Japanese Nichicons, a well respected brand today. (I could just imagine him being stopped at the Mexico to USA border and and the Officer saying what is in the boot ?, reply: ...Gulp, well I'm attempting to smuggle in some contraband BA thread screws !

So were PET computers manufactured at least partially in the UK, or were they all imported I wonder ?

I also found this on Wiki:

In 1979, Commodore replaced the original PET 2001 with an improved model known as the 2001-N (the N was short for "New"). The new machine used a standard green-phosphor monitor in place of the white in the original 2001.

So I guess this is how people distinguish the newer Pets in some cases.
 

daver2

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I don't recollect a PET production facility in the UK - but that is not a definitive statement of course.

If your friend (or you) need some BA hardware - I can just nip down to the local hardware store and put some in the post to you!

There is also a scenario where parts were in short supply for the PETs - so some machines got whatever parts happened to be available to hand. This may have included monitor boards and CRTs (especially in the window where Commodore were switching from one machine specification to another). You may find a 'new' machine with an 'old' monitor or vice versa. It all adds to the fun :)!

Dave
 

Eudimorphodon

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In 1979, Commodore replaced the original PET 2001 with an improved model known as the 2001-N (the N was short for "New"). The new machine used a standard green-phosphor monitor in place of the white in the original 2001.

So I guess this is how people distinguish the newer Pets in some cases.

To amplify daver2's comment, with regards to any and all claims like this the thing you always need to remember that they're basically just rules of thumb. Commodore seems to have played extremely fast and loose in terms of tossing together machines out of whatever parts they had around that day. FWIW, my chicklet 2001-no-N has a green monitor, not a white one, and that doesn't seem to be that rare. (And the reverse, -Ns with white, is also definitely a thing.)

For a microcosm of just how "diverse" PETs are, see Steve Gray's page of PET label variants. There seems to be almost no rhyme or reason as to why so many variations exist, it sometimes seems like whoever ordered a batch of labels on a particular day just made up something. Otherwise identical machines will have different labels. Or you'll have machines that have the same label but one has the (more common) steel case while another has the plastic one. Etc, etc.
 

Hugo Holden

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Or you'll have machines that have the same label but one has the (more common) steel case while another has the plastic one. Etc, etc.

I had no idea there were plastic cased PETs until I got mine. I was pleasantly surprised because the plastic is very solid with no evidence of degradation and has an excellent fine textured white coating. There was a mark on it, that looked like scratched paint in the auction photo, but it was just a small splash of black ink, and it cleaned off right away with some IPA, so cosmetically at least the case looks wonderful.

According to Steve Gray's page, my CBM 3008 is a re-labelled 2001 machine , this seems correct.
 
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Eudimorphodon

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According to Steve Gray's page, my CBM 3008 is a re-labelled 2001 machine , this seems correct.

Just remember that "2001" is itself kind of a meaningless term, since it basically covers almost all 40 column PETs up until BASIC 4.0 came out, at which point they switched to the 4000 nomenclature. I have two complete and one partial 9" PET that I picked up at a warehouse dump years ago, at which I got to see at least a hundred PETs in the flesh; Comparing them to the examples on Steve's page my "chicklet" has a sticker version of the white-text "PET 2001 Series Professional Computer" plastic bezel, my metal-cased 9" 32K PET has a sticker version of the high-rise "Model 4032 Computer" sticker, and I have a plastic case that I *think* is an exact match, except in Bezel form, of the the Chicklet's label, but it's hidden up in the attic so I can't double-check that. But particularly when it comes to the 4032, the warehouse I got it from had a ton of machines that were electrically identical but they had a variant of the 2001 Series sticker on them; same motherboard, same everything, with the possible exception of BASIC version.

(Some of these machines were actually upgraded to BASIC 4.0 and had their old ROMs taped inside.)
 

Hugo Holden

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(Some of these machines were actually upgraded to BASIC 4.0 and had their old ROMs taped inside.)
I think it is a good idea to keep spare parts inside machines, if there is a way to safely store them and the room. In some instances I have put hard to get schematics inside machines/apparatus. Some manufacturers used to do this. I have a number of radios, even a Tube tester, where the schematics were included inside the cases, all very helpful when it comes to repairs later.

Hundreds of PET's all in one place, that would have made quite a photo and probably now, no such thing will be seen again.

I was reading on another post about difficulty getting original ROMs for PET's.

Since a 2716 ROM works in the socket in my PET (for the Edit ROM at least), would I be wise to copy all of the other ROMs there in my PET and make duplicates in 2716's as spares/backups ?

If I attempted that, will the programmer read the existing ROM types as if they were a 2716 ?
 
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dave_m

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I was reading on another post about difficulty getting original ROMs for PET's.

Since a 2716 ROM works in the socket in my PET (for the Edit ROM at least), would I be wise to copy all of the other ROMs there in my PET and make duplicates in 2716's as spares/backups ?

If I attempted that, will the programmer read the existing ROM types as if they were a 2716 ?
Hugo,
That post must have been referring to the original ROMs in the 2001-8. They were the Commodore 6540 are very rare and not compatible with the later Commodore 6332/2332 ROMs of the 2001N.

All the ROMs in the 2001N are the newer 6332/3232 24 pin 4K byte except for the EDIT ROM which is the 6316 24 pin 2K byte ROM. The 6316 is compatible with the 2516 or the 2716 EPROM, but the other ROMs in the PET can only use the 2532 EPROM as a pin-for-pin replacement. The 2732 EPROM would need an adapter as it is NOT pin-or-pin with the 6332 ROM.

The 2516 and 2532 EPROMs are getting hard to find, but seem to be plentiful from China. Also one would need a very old EPROM programmer to burn the 2532 versus say a 27C32.

Let me know if you want a set of 2532 programmed EPROMs for your PET and I will send them to you because you help so many people on this forum with their video monitor issues.
-dave_m
 

Hugo Holden

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Hugo,
That post must have been referring to the original ROMs in the 2001-8. They were the Commodore 6540 are very rare and not compatible with the later Commodore 6332/2332 ROMs of the 2001N.

All the ROMs in the 2001N are the newer 6332/3232 24 pin 4K byte except for the EDIT ROM which is the 6316 24 pin 2K byte ROM. The 6316 is compatible with the 2516 or the 2716 EPROM, but the other ROMs in the PET can only use the 2532 EPROM as a pin-for-pin replacement. The 2732 EPROM would need an adapter as it is NOT pin-or-pin with the 6332 ROM.

The 2516 and 2532 EPROMs are getting hard to find, but seem to be plentiful from China. Also one would need a very old EPROM programmer to burn the 2532 versus say a 27C32.

Let me know if you want a set of 2532 programmed EPROMs for your PET and I will send them to you because you help so many people on this forum with their video monitor issues.
-dave_m
Thanks Dave_m, that is a kind offer. And for the info.

I think my programmers can do a 2532. It is listed on the GQ-4x supported devices and my BP1400 can do the 2532 and the 2532A (whatever that variant is) . So presumably I can read my existing ROMs too.

I'll get some 2532's and have a punt at programming some & see what happens, should be fun. It would be good to clone the ROMs in case they start to fail. The originals look to me like they were probably OTP fuse burnable types, so they should, in theory, be pretty good.

It looks like I got lucky with the PET version I got, with is 32k memory and the later ROMs. I had no idea, as the auction photo did not show the innards and it was pot luck.
 

Hugo Holden

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The TMS2532A is a 21 volt programming version and the plain 2532 is the standard 25V version.

I have been reading on the net that people have had a lot of trouble programming the 2532A. I got some of both IC's coming from the far east, so it will be interesting to see.

Some people have been cursed with receiving fake ones. These are used on video game boards it appears.

At least the BP1400 appears to support the 2532A as well as the 2532. When I bought the BP1400 I wondered if I was doing the right thing, but it came with the original manuals and software disk and it was in very good order and working. So although I paid a small fortune for it, at least it is helping me.
 

Nivag Swerdna

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Slightly off topic but I have a BP-1200 I bought at auction but have never got it to work... @Hugo... which software? How do you run it?
 

Hugo Holden

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I guess the BP 1200 and 1400 are similar, but not sure.

The BP 1400 manual comes with a CD inside it, that is used to load the Drivers and GUI for the BP1400 onto the host computer. It loaded and installed ok on my 2003 vintage HP desktop computer running XP and an Athlon 64 CPU. It then communicates via the parallel port, rather than the serial port which is interesting. I tried to make a clone of the CD, but I think it has some sort of copy protection on it.

So you would need to look around for the CD & Manual or I doubt if it would be possible to run a BP1400/1200 as the drivers install from the physical disk. It might I guess be possible to download a driver from somewhere, I tend to have very little luck getting this sort of thing to work, and some of the time I cannot even succeed with the manufacturer's original disks ! So when I buy vintage computer stuff that has support software that makes it work I only buy it usually if it comes complete, manuals & software, otherwise the card/device etc is useless and I'm wandering around in the dark not knowing what to do. Possibly the earlier machines had the software on a floppy, I am not sure.
 
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Hugo Holden

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Nivag, I just saw this blog from a year ago, so I guess you were never able to get any of those driver downloads working (which I mentioned is often what happens to me)


My XP computer is a 32 bit system and the software is called BPwin, so it is designed for Windows. My understanding is that later windows versions do things to restrict access to the ports. Maybe some of those downloads might work on the earlier windows versions, but at least it is known to work in XP, for the BP1400. I have had no trouble with it, but of course it did the software install from the manufacturer's disk.

I found this on an old thread:

 
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Hugo Holden

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Back onto the PET computer.

The more I work on this computer, the more I seem to like it.

I think Commodore did a really nice job on the design of the computer housing, including the VDU, which very sensibly came as part of the computer. With the SOL-20, for example, it was a mish-mash of different VDU's or modified TV's, depending on what a person could get.

The PET 9" VDU also appears to be an excellent size with respect to the overall size of the PET, perhaps not ideal for an 80 column display , but spot on for a 40 column one.

Plus the shape of the VDU enclosure, with its angular look and tapering sides. I'm not entirely sure why, but the whole geometry of that design does something for me, I really like the look of it. The computer might very well have escaped from a scene in the movie 2001 Space Odyssey, if they had been thoughtful enough to put one in there. It really seems to capture the magic of the 1970's computing era.

I wasn't 100% sure about the PET/CBM computers as I had never actually seen one in the flesh, only internet photos, so I initially lacked the confidence to buy one. But now that I have, I'm very glad I did, I think it may well be the best vintage computer I will ever own.
 
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daver2

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I used an original 40 column 9" 'chicklet' machine and the much later 8032 80 column PET with a disk drive at University. Along with a Tektronix 4051. If you wanted Graphics - the Tektronix 4051 was the machine. But both of them had IEEE488 ports and access to laboratory equipment tape loggers, printers, plotters etc.

As a 'student' there was no way I could afford one at the time. I can now...

Dave
 

Eudimorphodon

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I think it may well be the best vintage computer I will ever own

After getting my PETs I was likewise pleasantly surprised how much they grew on me. The 9" PET, even the original "toy keyboard" model, feels more like a piece of scientific lab equipment than a home computer. There are both upsides and downsides to that, I guess, but compared to something like the original TRS-80 if nothing else the sheer indestructibility of the PET is remarkable to behold.

I've always kind of felt like Commodore was running around like a chicken with its head chopped off when it came to their 8-bit machines in the 1980's; the Commodore 64 was hugely successful, sure, but it kind of feels like it was an accidental winner that just happened to emerge from the sheer quantity of stuff they randomly threw at the wall. (*) The PET by comparison feels to me like there was... actual "intention", in the design. Ultimately I think Commodore kind of missed the mark in terms of what "computer" evolved to mean among the public at large, but as an embodiment of what people might have dreamed of in the mid-1960's as the sort of "personal computer" they might actually be able to afford by 1980 the PET feels absolutely spot-on. It's very retro-futuristic.

(* And ironically enough most of those machines were essentially remixes of the PET's underlying software architecture.)
 
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