78 votes
Accepted

Can a PET 2001 be physically damaged from BASIC?

POKE 59458,62 was a trick, sometimes called "Fast Print," used to increase screen refresh rates on older PETs. This page describes the trick succinctly: the system no longer waits for the video ...
Kevin Duggan's user avatar
40 votes
Accepted

Why were early personal computer monitors not green?

The reason was cost, since neither the original PET nor the TRS-80 required the extra high resolution and finer dot pitch found in more expensive computer monitors. Virtually all of the computer ...
Brian H's user avatar
  • 60.5k
35 votes

What's the deal with Commodore's RESTORE key?

TL;DR: There is no fundamental difference just because a different interrupt is used. For all practical purpose the Restore-key works like the Apple II's Reset-key or the PC's Ctrl-Alt-Del key ...
Raffzahn's user avatar
  • 219k
28 votes

Who wrote the MS BASIC on the PET/C64/etc?

It is well established that Microsoft's 6502 BASIC (and Commodore BASIC is just a manufacturer specific adaption) is a port of the original 8080 BASIC done for the Altair -- alas, not a direct one, as ...
Raffzahn's user avatar
  • 219k
26 votes

Why were early personal computer monitors not green?

The answer, as always, was cost. 'White' CRTs were cheaper because they were used in B/W TV sets. The color itself has no impact on resolution, but TV tubes didn't need to be as sharp so they could be ...
Bruce Abbott's user avatar
  • 6,653
24 votes
Accepted

C64/PETSCII block graphic symbol: was there ever a logical reason for their "ASCII" codes?

The "PETSCII" encoding is based on keyboard positions of the original PET chicklet keyboard (*1): (Taken from Wikipedia) The keyboard is made similar to basic typewriter keyboards, but ...
Raffzahn's user avatar
  • 219k
23 votes
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Computers with integrated monitor (all-in-one form factor)

It's a little cheaper to build all-in-one units because you only need one cabinet and one power supply, and you need fewer cables and connectors and supporting electronics. And back then, people didn'...
snips-n-snails's user avatar
23 votes
Accepted

How were printouts done on Commodore PETs

I used to: OPEN 4,4: CMD 4: LIST CMD redirected the $FFD2 output routine to the specified file. Of course, you needed a printer that understood the PET special characters. The CBM 2022 and 2023 did.
user3486184's user avatar
22 votes
Accepted

What was the end of line convention for text files on the 8-bit Commodores

C64 Basic used a CR as EOL for disk files. (source: Commodore SX-64 User's Guide, page 22: “CR stands for the CHR$ code 13, the carriage return, which is automatically PRINTed at the end of ever ...
scruss's user avatar
  • 21.5k
20 votes
Accepted

Why was PETSCII based on an obsolete version of ASCII?

TL;DR PETSCII isn't "based on ASCII". Rather, the specifications Commodore wanted for PETSCII caused them to "back into" supporting the only version of the ASCII standard that didn'...
Brian H's user avatar
  • 60.5k
18 votes
Accepted

How did the Commodore PET 80 column display work?

As Tommy wrote in the comment: There are two different RAM chips, one for even columns and one for odd columns. Both are read and latched in one cycle (ESD and OSD bus), and the latched output of each ...
dirkt's user avatar
  • 27k
18 votes
Accepted

What's the timeline of Commodore diskette drives?

You can get a relative ordering by looking at DOS versions for the drives. IEEE-488 drives 2040 - first drive, 5.25"x2@170K, 1979, DOS 1.0 3040 - 5.25"x2@170k in Europe, 1979, DOS 1.2 4040 -...
user3486184's user avatar
16 votes
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PET space arcade game with surprisingly good graphics

And it's definitely Star Spores. I found an interview with the author, who it turns out lives fairly close to me, and he mentioned the line-drawing routine which I'm sure is referring to the lightning ...
Maury Markowitz's user avatar
15 votes

Is there software that will run across multiple Commodore 8-bit machines without modification?

BASIC games that use no memory specific code can be ported between different commodore machines. (I did some successfully between PET and C64). Machinecode games could be transferred between some ...
EL Dendo's user avatar
  • 1,112
15 votes
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How should I repaint my Commodore PET?

Preface, I assume you already checked related questions like: Cosmetically restoring vintage equipment Will careful restoration of a retrocomputer's paint job enhance its value? How to repair paint ...
Raffzahn's user avatar
  • 219k
14 votes
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What is this code on the zero page that was put there by the BASIC ROM?

It's part of the BASIC interpreter loop. It reads one byte of the tokenized BASIC program, setting zero flag if it's a colon or a zero byte and clearing the carry if it's a number. You can see it used ...
14 votes
Accepted

Origin of dealer networks

You'd be surprised. There were specialist microcomputer shops in the late 1970s. I'm talking now about the UK and the shops that I used to visit. These were either individual shops or small chains, ...
Chenmunka's user avatar
  • 8,111
14 votes

PET space arcade game with surprisingly good graphics

This was indeed Jim Summers who wrote Star Spores. He also wrote Slime and Astro-Rescue. You can find them on my site, with his permission. Star Spores
Marcel's user avatar
  • 176
13 votes

Obscure uses of the Commodore 8050/1541 disk drive

There were a number of programs that used the 6502 in the 1541 as a coprocessor. An obvious application was for calculating fractals, because that doesn't need a lot of RAM. An example is the ...
dirkt's user avatar
  • 27k
13 votes

Obscure uses of the Commodore 8050/1541 disk drive

And now this: disk drive outputs the video signal through the serial bus connector! "Freespin" Demo by Matthias Kramm (Quiss/Reflex): https://www.youtube.com/watch?v=zprSxCMlECA Technical ...
szulat's user avatar
  • 270
13 votes
Accepted

Is it possible to bank out Kernal in Commodore PET, VIC-20 or 264 series computers?

You cannot do that on the VIC-20; not only is no such feature provided by the built-in hardware but there's also no ROMDIS signal on the memory expansion bus or anything else similar. PETs with a ...
Tommy's user avatar
  • 36.6k
13 votes
Accepted

Why didn't the original Commodore PET computer use a standard typewriter style keyboard?

Why didn't the original Commodore PET computer use a standard typewriter style keyboard? Putting aside that 'why not' is a hypothetical question thus a definitive answer can rarely been given, it's ...
Raffzahn's user avatar
  • 219k
12 votes

Is there software that will run across multiple Commodore 8-bit machines without modification?

It seems that Michael Steil at pagefault.org has recently posted an analysis of the KERNAL calls from all of the Commodore 8-bit machines to try and track lineage. However, what is relevant here is ...
bjb's user avatar
  • 16.2k
12 votes

Obscure uses of the Commodore 8050/1541 disk drive

Playing music with the drive heads, of course. I've tried that too, wrecking the drive in the process. Dimming the drive LED, by flashing it very fast, with a variable duty cycle. Printing a file on ...
followed Monica to Codidact's user avatar
12 votes

Who wrote the MS BASIC on the PET/C64/etc?

The following article details some of the early history of Commodore BASIC (including other Microsoft BASIC 6502 versions), particularly v1 and v2. Create your own Version of Microsoft BASIC for 6502 ...
Tim Locke's user avatar
  • 4,801
12 votes

PET as a terminal

I don't have any experience with the exact modification you are talking about. However, I think it is a relevant point that the design of the firmware for Commodore microcomputers included a "...
Brian H's user avatar
  • 60.5k
11 votes

Origin of copy-protection dongles

The oldest (smart) hardware "dongle" I know of is from 1985 in the ZX Spectrum 48K. To curb piracy and as a "collateral side effect" also having more 16KB (e.g. 64KB for the game), ...
Rui F Ribeiro's user avatar
10 votes

Obscure uses of the Commodore 8050/1541 disk drive

Reposting slightly, but this (German-language) page provides software for networking C64s via the serial bus, with the simplest intended power-on state being two C64s connected to the two inputs of a ...
Tommy's user avatar
  • 36.6k
10 votes

Can a PET 2001 be physically damaged from BASIC?

This jogged me memory about a pretty well known problem with early PC video control hardware that could, if programmed with really incorrect video timing, result in damage to the flyback power supply ...
idzombak's user avatar
  • 101
10 votes

Did all integrated Commodore PET monitors always use 60 Hz refresh?

TL;DR: Non-CRTC PETs (Original PET, early 30xx) are fixed to 60 Hz. CRTC (6545) based PETs (40xx/80xx/8x96/9000 - *1) use screen refresh rates set by its ROM (*2). 50 Hz for European machines, 60 Hz ...
Raffzahn's user avatar
  • 219k

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