Retrocomputing

1150 Articles

Behold A First-Person 3D Maze, Vintage Atari Style

October 20, 2024 by 15 Comments

[Joe Musashi] was inspired by discussions about 3D engines and decided to create a first-person 3D maze of his own. The really neat part? It could have been done on vintage Atari hardware. Well, mostly.

He does admit he had to do a little cheating to make this work; he relies on code for the ARM processor in the modern Atari VCS do the ray casting work, and the 6507 chip just handles the display kernel. Still, running his demo on a vintage Atari 2600 console could be possible, but would definitely require a Melody or Harmony cartridge, which are special reprogrammable cartridges popular for development and homebrew.

Ray casting is a conceptually simple method of generating a 3D view from given perspective, and here’s a tutorial that will tell you all you need to know about how it works, and how to implement your own.

[Joe]’s demo is just a navigable 3D maze rather than a game, but it’s pretty wild to see what could in theory have run on such an old platform, even if a few modern cheats are needed to pull it off. And if you agree that it’s neat, then hold onto your hats because a full 3D ray casting game — complete with a micro physics engine — was perfectly doable on the Commodore PET, which even had the additional limitation of a monochrome character-based display.

Inside The RLL Hard Drive Protocol

October 19, 2024 by 19 Comments

If you are younger than a certain age, RLL probably doesn’t mean much to you. Old consumer-grade hard drives used MFM (modified frequency modulation like a floppy disk uses) and soon went to IDE (integrated drive electronics). There was a brief period when RLL (run length limited) drives were the way to get a little more life out of the MFM technology. [W1ngsfly] has an RLL drive on his bench and uses his scope and some other gear to put it through its paces. You can watch over his shoulder in the video below.

The hardware interface and drive are the same for an MFM and an RLL drive. However, an RLL-aware controller can pack more bits on the same platter by using the newer modulation scheme. Some older disks were good enough for MFM but too sloppy to successfully take an RLL format, but — in theory — any MFM drive could be an RLL drive and vice versa.

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Building A ZX Spectrum Using Only New Parts

October 17, 2024 by 29 Comments

Ah, the Sinclair ZX Spectrum. A popular computer in Britain and beyond, but now rather thin on the ground. If you can’t find one, fear not, for now—you can apparently build a new one with new parts! [TME Retro] is here to demonstrate how.

Before you get excited, no—Sinclair has not risen from the dead. Instead, it’s simply down to the state of the retrocomputing community. There are enough reproduction parts and components out there for the ZX Spectrum that it’s now possible to assemble the whole computer from new bits. You can get new cases and new mechanical keyboards, and a 100% compatible motherboard in the form of the Harlequin board. The latter even reproduces the unobtainable Spectrum ULA glue logic chip in raw logic!

It’s neat to see the ZX Spectrum live on decades after the production lines ground to a halt. We’ve seen similar feats achieved with the legendary Commodore 64; you’d think we had enough of them given they were the best-selling computer of all time. Video after the break.

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Access The Information Superhighway With A Mac Plus

October 17, 2024 by 5 Comments

For some time now, Apple has developed a reputation for manufacturing computers and phones that are not particularly repairable or upgradable. While this reputation is somewhat deserved, especially in recent years, it seems less true for their older machines. With the second and perhaps most influential computer, the Apple II, being so upgradable that the machine had a production run of nearly two decades. Similarly, the Macintosh Plus of 1986 was surprisingly upgradable and repairable and [Hunter] demonstrates its capabilities by bringing one onto the modern Internet, albeit with a few tricks to adapt the old hardware and software to the modern era.

The Mac Plus was salvaged from a thrift store, and the first issue to solve was that it had some rotten capacitors that had to be replaced before the computer could be reliably powered on at all. [Hunter] then got to work bringing this computer online, with the only major hardware modification being a BlueSCSI hard drive emulator which allows using an SD card instead of an original hard disk. It can also emulate an original Macintosh Ethernet card, allowing it to fairly easily get online.

The original operating system and browser don’t support modern protocols such as HTTPS or scripting languages like Javascript or CSS, so a tool called MacProxy was used to bridge this gap. It serves simplified HTML from the Internet to the Mac Plus, but [Hunter] wanted it to work even better, adding modular domain-specific handling to allow the computer to more easily access sites like Reddit, YouTube, and even Hackaday, although he does call us out a bit for not maintaining our retro page perhaps as well as it ought to be.

[Hunter] has also built an extension to use the Wayback Machine to serve websites to the Mac from a specific date in the past, which really enhances the retro feel of using a computer like this to access the Internet. Of course, if you don’t have original Macintosh hardware but still want to have the same experience of the early Internet or retro hardware this replica Mac will get you there too.

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Linus Live-Codes Music On The Commodore 64

October 16, 2024 by 12 Comments

In this tremendously educational video, [Linus Åkesson] takes us through how he develops a synthesizer and a sequencer and editor for it on the Commodore 64, all in BASIC. While this sounds easy, [Linus] is doing this in hard mode: all of the audio is generated by POKE, and it gets crazier from there. If you’re one of those people out there who think that BASIC is a limited language, you need to watch this video.

[Linus] can do anything with POKE. On a simple computer like the C64, the sound chip, the screen chips, and even the interrupts that control program flow are all accessible simply by writing to the right part of memory. So the main loop here simply runs through a lot of data, POKEing it into memory and turning the sound chip on and off. There’s also a counter running inside the C64 that he uses to point into a pitch lookup table in the code.

But the inception part comes when he designs the sequencer and editor. Because C64 BASIC already has an interactive code editor, he hijacks this for his music editor. The final sequencer interface exists inside the program itself, and he writes music in the code, in real time, using things like LIST and editing. (Code is data, and data is code.) Add in a noise drum hack, and you’ve got some classic chiptuney sounds by the end.

We love [Linus]’s minimal C64 exercises, and this one gets maximal effect out of a running C64 BASIC environment. But that’s so much code in comparison to his 256-byte “A Mind is Born” demo. But to get that done, he had to use assembly.

Thanks [zogzog] for the great tip!

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The Greengate DS:3 Part 2: Putting A Retro Sampler To Use

October 14, 2024 by 2 Comments

The Greengate DS:3 had been re-created in the form of the Goodgreat. Now [Bea Thurman] had to put it to use. If the Greengate DS:3 card was rare,  the keyboard was nearly impossible to find. After a long search, [Bea] bought one all the way from Iceland.  The card of course came courtesy of [Eric]. 

It was time to connect the two together.  But there was a problem — a big problem. The GreenGate has a DB-25 connected via a ribbon cable to the board’s 2×10 connector. The keyboard that shipped with those cards would plug right in.  Unfortunately, [Bea’s] keyboard had a DIP-40 IDC connector crimped on its ribbon cable.  What’s more the connectors for the sustain and volume pedals were marked, but never drilled out. The GreenGate silk screen was still there though. 

Maybe it was a prototype or some sort of modified hardware. Either way, the 40-pin DIP connector had to go if the keyboard ever were to work with the card. What followed were a few hours of careful wire tracing 

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Solving A Retrocomputing Mystery With An Album Cover: Greengate DS:3

October 14, 2024 by 9 Comments

[Bea Thurman] had a retro music conundrum. She loved the classic Greengate DS:3 sampler, but couldn’t buy one, and couldn’t find enough information to build her own. [Bea’s] plea for help caught the attention of [Eric Schlaepfer], aka  [TubeTime]. The collaboration that followed ultimately solved a decades-old mystery. 

In the 1980s, there were two types of musicians: Those who could afford a Fairlight CMI and everyone else. If you were an Apple II owner, the solution was a Greengate DS:3. The DS:3 was a music keyboard and a sampler card for the Apple II+ (or better). The plug-in card was a bit mysterious, though. The cards were not very well documented, and only a few survive today. To make matters worse, some chips had part numbers sanded off. It was a bit of a mystery until [Bea and Tubetime] got involved. 

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