This is a 52-minute talk from 2010, from the 27th Chaos Communication Congress in Berlin, Germany (the talk is in English), presented by Michael Steil of Visual 6502, which successfully reverse engineered the venerable 6502 microprocessor, a chip used, in one capacity or another, in one form, or another, in all the Apple, Commodore and Atari microcomputers, the BBC Micro, the Atari 5200, in a modified from the Atari 2600 the NES, and countless arcade games, as well as in other places.
The talk is intended for a technical audience… literally. When the speaker asks who in the audience has coded in assembly before, practically everyone raises their hands. It’s recognized that we at Set Side B veer wildly between the most surface-level populist material and in-depth treatments for those with gigantic capacities for technical discussion and the attention span of a Galapagos Giant Tortoise. We like to think this is charming, and will listen eagerly if you tell us that you agree.
Anyway, here is that talk. I already mentioned that it’s 53 minutes. If that’s too long, there’s a speed-up function on Youtube. If that’s too technical, well, I don’t know how to help there. Maybe a read through pagetable.com’s documentation on the 6502. Oops! I’ve made it worse, haven’t I. Well, if you like, you might console yourself that the 6502 is really a simple processor to learn to code in. I’ve done it myself! There’s no memory management, there’s only three general-purpose registers, the stack is fixed in place, and all opcodes are one byte. It’s so simple that an extremely motivated child could learn it. Guess how I know?
This is an ad, on the first page of the first issue of Compute Magazine, for “the pet program” from “softside software,” names all in lowercase. I have no idea if any copies of these programs remains in existence in our universe, but two places to look would be zimmers.net’s FTP archive and the Silicon PET Archive, and even in this era of the internet there are a fair number of PET software archives remaining.
Softside was far from the only company to put out its hopeful shingle through the pages of early computer magazines. At the time, magazine publishing worked with a lead time of several months. It is possible that Softside Software had gone under even by the time this ad saw print, but then again maybe not. A forum thread on AtariAge mentions several BASIC games sold by a “SoftSide,” apparently an Atari 8-bit magazine-on-disk, but they were based in New Hampshire, and the Softside of the ad was in New York.
Notes on the programs proffered:
Graphics Pac 2: I’m not sure what they mean, as the reference I’ve found claims the PET didn’t have a bitmapped display, but there were several models, and further add-on cards that added bitmapped displays, an 80-column mode, and even (gasp) color. A simple “Microsette” itself would not be enough. We are near the end of the PET’s reign as Commdore’s core product though.
Assembler 2001: It is easy to laugh this off nowadays when assemblers are mostly free software (and thank frog for that), but this was before that, and before the internet. $16 is a great price for an assembler from that time.
Bike. Apparently it was a Hammurabi/Lemonade Stand style game, where you made business decisions through simple menus and entering figures. Maybe someday someone will write such a game about running Commodore. You might scoff at the warning that “Bike is dangerously addictive,” but standards were lower then. It was 1979; Wizardry wouldn’t be published until 1981. “Worth a million in fun, we’ll offer Bike at $9.95.” I admire their chutzpah.
Pinball. “Dynamic usage of the PET’s graphics features” would have meant using its hardcoded, unchangable ROM graphics character set, with no sprites. “With sound!” That would mean its simple piezoelectric speaker. Don’t expect Raul Julia’s voice, or even Gorgar’s, to talk to you from the machine.
Super Doodle. Certainly of no relation to Omni Software’s popular Commodore paint program. Super Doodle lets you use any number of colors so long as they’re black or green, and a resolution of 40×25 characters. “Why waste any more paper.” Well probably because loading your notes off of tape would take too long.
Driving Ace. Offers two games for $9.95. The description doesn’t give a good sense of what they were like, but there are essentially only three kinds of racing game: scrolling in one direction (Monaco GP style), one screen or scrolling all around (Sprint style), and 3D (Pole Position through to Ridge Racer to F-Zero). I presume one of these is like Sprint and the other is like Monaco GP; I don’t think the PET was capable of even a slight approximation of 3D, but then, Pole Position’s hardware shouldn’t have been capable of what it could do either.
The ad is from Compute Magazine, most often stylized as COMPUTE! with an exclamation point, grew out of The PET Gazette in 1979. That former publication centered around the computing devices from Commodore International’s subsidiary, Commodore Business Machines. CBM had been around for over two decades up to that point as a maker of typewriters, adding machines and calculators, but in a maverick move by its co-founder and president Jack Tramiel, they bought MOS Technologies, which had just startled the nascent computing world by creating an ultra low cost microprocessor, the 6502. Tramiel had learned from a bit of a bastard move by Texas Instruments, who used their ownership of much of their supply chain to release a line of calculators that sold for less than Commodore’s production costs. Now, Tramiel owned the company that produced the chip that would soon launch the personal computing revolution, and could make other chips too, and Commodore was set to soon pull off Texas Instruments’ trick on the home computer industry with the VIC-20 and Commodore 64.
But until then they made other computers. They made the KIM-1 “single board computer,” and the PET 2001 and other machines with the PET branding. The PET Gazette’s audience was originally those machines, but burgeoning success convinced them to publish a more generalized 6502-focused magazine, and that magazine was Compute.
I have more to come on Compute, which in many ways was the archetypal type-in program magazine. It was far from the only one; other magazines offering type-in software at the time, names now even more obscure than Compute’s, were Creative Computing, Family Computing, and Commodore’s own publications Commodore Magazine and Power Play. Compute would for a while languish somewhat in the shadow of its own sister publication, borrowing part of its name from its predecessor, Compute’s Gazette, which focused on Commodore’s computers, the VIC-20, the Commodore 64, and later the Commodore 128.
The PET Gazette was founded by Small System Services Inc., and was published out of a shop, the Corner Computer Store, in Greensboro, North Carolina. Presumably that changed as the subscription rolls increased. Eventually Compute would be sold to ABC Publishing, a subsidiary of the broadcast network, and it would continue happily for several years. When its fortunes began to wane it was sold, first to Penthouse Publishing (really!), where its logo was redone to resemble that of its own publication Omni, then later to Ziff-Davis, who only wanted its subscriber list anyway; I don’t think they ever published an issue. As it became clearer that the future would be MS-DOS and Mac, its focus shifted, but they kept up their small systems focus for surprisingly long. I don’t think the Penthouse era provided any coverage that wasn’t DOS, Windows or Mac, but it would take time to check. Corrections later, if necessary.
We’ve brought up a couple of examples of Commodore PET software lately, which as I keep saying, is interesting because the PET has no way of doing bitmapped graphics, sprites, or even definable characters. Its characters are locked in ROM and cannot be changed. So, it includes a set of multi-purpose characters that was used throughout all the Commodore 8-bit line, even as late as the C64 and C128, which having definable graphics didn’t need these kinds of generic graphics characters, but they were still useful for people who didn’t want to create their own graphics.
The PETSCII characters, as used on the Commodore 64 (image, with some editing, from Wikipedia). The graphics set also includes reverse-video versions of each character.
Back on my Commodore coding days I became very familiar with these characters. I think they’re much more universally-applicable for graphic use than the IBM equivalent, the famous Code Page 437, although that’s mostly because PETSCII doesn’t bother defining supporting so many languages. Code Page 437 also uses a lot of its space for single and double-line versions of box-drawing characters, although on the other hand it doesn’t waste characters defining reverse-video versions of every glyph.
PETSCII has:
A space and reversed space, of course.
Line drawing characters for boxes of course: vertical and horizontal lines, corners, and three- and four-way intersections. There are also curved versions of the corners.
More line-drawing characters for borders.
Still more horizontal and vertical lines, at each pixel position within their box.
With the reverse-video versions, enough characters to effectively do a 80×50 pixel display, as if it had a super low-res mode.
Different thicknesses of horizontal and vertical lines too.
Diagonal lines, and a big ‘X’. Note that on the PET and Vic-20 these lines were all one pixel wide, but on later computers with both better resolution and color graphics they were made thicker, which means diagonal lines have “notches” between character cells.
Other miscellaneous symbols: playing card symbols, filled and hollow balls, and some checkerboards for shading. On the PET and Vic, the shading characters were finer, while on the other 8-bit computers they were made of 2×2 boxes.
There are resources that let you use PETSCII to create old-school computer art, like this PETSCII editor, Petmate and Playscii, and for a bunch of examples of what you can do with it you can browse through the Twitter account PETSCIIBots. And this blog post from 2016 both makes the case for PETSCII as a medium for art and provides some great examples of it.
The Commodore VIC-20, Commodore’s first attempt at a budget color home computer, often gets lets out of the spotlight in favor of its more capable successor, the Commodore 64. Back at release it had significantly limited RAM even for the time, only 5K, and it also had only eight colors for general use, simple sound, and no hardware sprites. Even so, it did all right in the market, but was quickly overshadowed by Commodore’s more powerful followup.
But all of these factors mean that making substantial games for it is both a more interesting challenge, and a lot more impressive when it’s done well. Youtube channel RetroGamerNation did a roundup video of interesting VIC games made in 2022. Remember, when watching these videos, the VIC had no sprites. I personally like the look of Flood. Most of these games require significant RAM expansion to run (on the VIC-20, “significant” means at least 16 kilobytes), but many people who try them out will be running them on an emulator anyway, and one of the games actually runs on an unexpanded VIC.
