mass:werk / Blog

“Now Go Bang!” is named after a source comment in Spacewar!, the first digital video game.
It marks the very instance, when a spaceship which has been dragged into the gravitational star starts to explode. What follows, is impressionist pixel-dust floating along the ship’s former trajectory in a sparkling bloom of phosphor activation.

"now go bang" as found in the source code of Spacewar!

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A few tags:computerhistory, infographics, software, pet2001, basic, pdp-1, archeology, retrochallenge, mixed-bag, long-read.

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“PET-Globe” Demo

An avidly spinning globe for the Commodore PET — and some bit-vectors.

Screenshot: a green screen showing an animated globe rendered in PETSCII block characters.

Well, I made another thing — in #6502 code and #PETSCII.

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Happy New Year

Well, another one…

A monochrome screen with PETSCII graphics showing the globe and a some stars and a large-pixel Space Invader in the front, intersecting the globe. A heading in fancy lettering reads ":Happy New Year".

(Foreshadowing not totally out of question, but also not guaranteed. I mean, the year isn’t even a day old! :-) )

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Love for the WDC 65C02

WDC and Rockwell related additions to the 6502 instruction set sheet.

Screenshot of the 6502 instruction table with newly added supportfor WDC extensions.

Just added Western Design Center (WDC) and Rockwell extensions to the standard instruction set of the 6502 processor to the well-received 6502 Instruction Set page.
There’s now an additional view option for the instruction table, as well as new sections providing details on WDC 65C02(S) specifics and Rockwell extensions (linked at the top of the page) for their respective variants of the venerable 6502. Moreover, in order to avoid confusion, the section on “illegal” opcodes is now marked as specific to the original NMOS version.

While WDC’s 65C02 is really the only version of the 6502 still in production, the fact that WDC-datasheets are neither the clearest, nor the most complete, may have contributed to a relative obscurity of the additional instructions and behavioral differences. Maybe, including them in a one-stop documentation will help, just a bit? Or even eight? ;-)

Also, as a minor improvement, the page should be now easier to tab through (lots of tabinidces).

A Guide to Commodore PETs

The original line-up of Commodore PET computers at a glance.

various models of the Commodore PET computer arranged in quadrants of the image

While Commodore PETs are quite easily and unmistakably identified by their unique form factor, the basic model evolved quite a bit over the years. Here’s a comprehensive guide to the various models of the original line-up (not including the later series with rounded case and separate keyboard) and their basic features.

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2024 X-Mas Demo (Commodore PET)

It’s that time of the year, again…

Screenshot: silhouette of a moonlit forest and Santa's sledge flying accross the screen, rendered in blocky PETSII graphics.
1 REM ***** 2024 X-MAS DEMO ***** 2 REM HTTPS://WWW.MASSWERK.AT/PET 3 REM *************************** 4 SYS 1140

This year’s seasonal tribute: a PETSCII animation based on a popular cross-stitch pattern.
Users are kindly requested to imagine that trademark eerily fluttering 1950s UFO sound effect that I find hard to achieve on the PET’s “CB2” sound*.

  • Ingredients: MOS 6502 assembler, PETSCII graphics (rendering at quarter blocks), CB2-sound.
  • Requirements: any 40-columns PET, any ROM version, any RAM (4K or better).
  • Download: masswerk.at/pet/prgs/#xmasdemo2024

>Emulation: run it online

*) In case you were to ask, “What is CB2-sound?”
Well, the PET doesn’t feature sound, at all. But you can hook up a speaker to the output of a serial shift-register, creatively named “CB2”, which may be manipulated to output audible frequencies, sampling sound by a single bit at 1 MHz. This is CB2-sound.

Emulated hardcopy of the wiring diagram for CB2-sound on the Commodore PET
The famous wiring diagram for CB2-sound on the Commodore PET from the “Space Invaders” game. Later PETs included a built-in speaker, connected in the same fashion internally.

*****

The already tradional PET recreation of an animated screen of the 1982 Christmas Demo for the C64 has also received an update: it now fits into 4K of RAM and allows for easy updates, as the year is now stored in a dedicated variable at the very top of the BASIC program text.

Screenshot: an Advent arrangement with a candle in the middle featuring an animated flame in pure PETSCII graphics
100 REM PET 2001 - SEASON'S GREETINGS 110 REM NORBERT LANDSTEINER, 2017-2024 120 REM <WWW.MASSWERK.AT> 130 Y=2024:REM YEAR
(You may set Y to zero to omit the output of the year entirely.)

>Emulation: run it online

Japanese Attractions: Kana on the PET 2001

The Japanese character ROM and keyboard come to the PET 2001 emulator.

Katakana on the Commodore PET 2001 (emulation)

Another update to the PET 2001 emulator, spefically, a tribute to Japan and its importance to home computing history in general, and its role for Commodore in particular.

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