Retrocomputing

1587 Articles

SCSI: The Disk Bus For Everything

March 2, 2023 by 72 Comments

Early home PCs usually had a floppy disk and a simple hard drive controller. Later, IDE hard drives became the defacto standard. Of course, these days, you are more likely to find some version of SATA and — lately — NVME connectors. But a standard predating all of this was very common in high-end systems: SCSI. [RetroBytes] recently did a video on the bus which he calls the “USB of the 80s.”

Historically, Shugart — a maker of disks — was tired of producing custom drive electronics for each device they made. Instead, they made disks with a standard interface and then produced a single interface board for each computer they wanted to support. The interface was very generic, and they were able to get it standardized with ANSI — an early example of the benefit of opening up a standard.

Continue reading “SCSI: The Disk Bus For Everything” →

Brand New Colecovision Console – On A Breadboard

March 1, 2023 by 4 Comments

The Colecovision console from the early 1980s is probably not the most memorable platform of its era, but it retains a retrocomputing following to this day. The original hardware can be a bit pricey in 2023, so [nanochess] has built one of his own on a breadboard. It’s fully functional from original Colecovision cartridges, and we see it in the video below the break running Frogger.

Behind the mess of wires is a surprisingly simple circuit with only a few logic chips beyond the Z80 processor, the various memory and EPROM chips, and the video and sound chips. We’re told the complexity is considerably reduced by the use of a Texas Instruments  TMS9118 video controller instead of a 9918.

Had we been building it we would probably have taken the less brave step of using color coded wires for the various signals, because we remember the fun and games associated with wiring old-style 8-bit computers by hand only too well. But we have to admit that it reminds us of a lost youth working out Z80 address decoder schematics, so it’s very pleasing to see one built today.

If you’re hungry for more Coleco goodness, this isn’t the first home made Colecovision we’ve brought you.

Continue reading “Brand New Colecovision Console – On A Breadboard” →

Trying (and Failing) To Restore A 1970s CDC 10MB Hard Drive

February 28, 2023 by 34 Comments

One fun aspect of 1970s-era hard disk drives is that they are big, clunky and are fairly easy to repair without the need for a clean room. A less fun aspect is that they are 1970s-era HDDs and thus old and often broken. While repairing a CDC 10 MB HDD for the upcoming VCF East event, the folks over at [Usagi Electric], this led to quite a few struggles, even after a replacement 14″ platter was found to replace the crashed platter with.

These CDC HDDs are referred to as Hawk drives, and they make the associated 8-bit Centurion  TTL logic-based computers so much faster and easier to work with (for a 1970s system, of course). Despite the large size of the components involved and the simple, all through-hole nature of the PCBs, issues that cropped up ranged from corroded DIP switches, to head alignment sensors, a defective analog board and ultimately a reported bad read-write head.

Frustratingly, even after getting the platters to spin up and everything moving as intended, it would seem that the remaining problem is that of possibly bad read-write heads, as in plural. Whether it’s due to age, previous head crashes onto platters, or something else, assembling a working Hawk drive turned out to be somewhat more complicated than hoped.

We definitely hope that the bunnies can get a working Hawk together, as working 1970s HDDs like these are become pretty rare.

Continue reading “Trying (and Failing) To Restore A 1970s CDC 10MB Hard Drive” →

MorphOS: A Modern Operating System For PowerPC

February 27, 2023 by 29 Comments

When it comes to modern operating systems for PowerPC-based systems like pre-Intel Macs, or other PowerPC-based systems like older or newer AmigaOS-compatible systems, there is an increasing lack of options. For 32-bit PPC, official Linux support has been dropped already, leaving only unofficial builds and of course AmigaOS as well as AmigaOS-like operating systems. So what do you do if you have a PPC-based Mac system lying around which you do not simply want to run the same old, unsupported copy of MacOS on? In a recent video, [Michael MJD] decided to give MorphOS 3.17 a shot on a Mac G4 Cube.

Originally created for the now-defunct Pegasos PPC-based series of computers and PPC accelerator cards for Amiga systems, MorphOS is based on the proprietary Quark microkernel, In its current release, it supports a range of G4 and G5-based Apple systems, as well as the AmigaOne 500 and X5000, with some asterisks. In addition to its own applications it supports AmigaOS applications, including those targeting the m68k architecture, via its JIT emulator.

A cursory look at the community shows that MorphOS finds use for being a fast and relatively up to date alternative OS for especially PPC-based Macs. The price tag of €79 per system (transferable to a new system) should offer some guarantee of continued development, which includes e.g. the Wayfarer browser for MorphOS, which is based on Webkit, but optimized for e.g. Altivec.

Although installing MorphOS went relatively smoothly for [Michael] (with just a monitor-related glitch), he did not try too much beyond an initial impression of the GUI and preinstalled applications. There is also a 30-minute timer on the trial version (resettable via reboot) that ended [Michael]’s look at this OS.

What do you run on your PPC-based machines, and have you used MorphOS? What are your thoughts on this OS?

Continue reading “MorphOS: A Modern Operating System For PowerPC” →

Emulating All The TRS-80 Software

February 27, 2023 by 37 Comments

Even if you didn’t own a TRS-80, the widespread footprint of Radio Shack in malls meant that if you are old enough, it is a good bet you have seen one and maybe even played with one. The games were crude, but state-of-the-art for 1982. If you wanted business software, that was there too, just don’t expect much on any of the personal computers of the day. My old TRS-80 Model III doesn’t boot anymore and is waiting for me to find time to pull it apart. But it turns out you can run all those old programs with almost no effort. If you’ve experimented with emulators before, you know there are two major problems. First, you need to install the sometimes-fidgety emulator. Second, you need to find the software you want to run and probably convert it into some format the emulator will read. The website named The Big List of TRS-80 Software solves both problems.

You are probably thinking this doesn’t solve any problem because it is just a list of links to software. That’s a reasonable thing to think, but we think the website really needs a new name. There are 15,873 pieces of software on the site, although some of them are duplicates or multiple versions of a single program. You can download them in a format that is useful for some emulators or, in some cases, the original files. But here’s the kicker. You can also click to launch a virtual TRS-80 in your browser and start the program.

Sounds great, right? Well, for the most part, it is. However, some of the programs are finicky and don’t run well in the browser. There’s also the problem of finding the documentation, but you can’t have everything. If you want a quick run of a very common game from back in the day, try Flying Saucers. Continue reading “Emulating All The TRS-80 Software” →

The Forgotten Commodore 900: A Look At A Rare Prototype

February 25, 2023 by 28 Comments

Of the computers produced and prototyped by Commodore, most people are likely well-acquainted with the PET, VIC-20, C64 and C128, as well as the never released Commodore 65. Of these systems many examples and plentiful of documentation exist, but probably among the most rare is the Commodore 900, as recently covered by [Neil] over at RMC – The Cave on YouTube. The Commodore 900, conceived in 1983, was intended to become a microcomputer based on the 16-bit Zilog Z8001 CPU that targeted businesses as a UNIX workstation.

Only fifty prototypes were ever built of the C900 and no hardware was ever sold, even though the intended UNIX-based OS (MWC’s Coherent) had already been ported to the Z8000 and the rumor mill suggested a release in 1984. Although UNIX workstations were rather popular during the 1980s — with HP and Sun featuring prominently in this market segment — Commodore was more known for its home computers, which probably played a major role in C900 development being cancelled. At the time Commodore was also in the process of acquiring Amiga, with the C900 perhaps unsurprisingly featuring similar design language as the Amiga 2000.

Perhaps ironically, the Z8000 CPU that features in the C900 had a bit of a tragic history as well. Although featuring a range of interesting features, such as the ability to use its registers as 8-, 16-, 32- or even 64-bit registers by combining them as needed. Although this and the general performance of the Z8000 made it a solid CPU, it could not compete against the Motorola 68000 and Intel 8086/8088 CPUs when those appeared on the market.

In the video, [Neil] takes us through a detailed history of the C900, its feature list and the hardware inside the C900 prototype he got his hands on. It’s a fascinating glimpse at a part of Commodore history where this company almost went toe to toe with Sun, HP and other workstation giants.

Continue reading “The Forgotten Commodore 900: A Look At A Rare Prototype” →

Deep Dive Into The HP ScantJet 4C

February 24, 2023 by 28 Comments

[Shelby] at Tech Tangents recently wrapped a project / obsession to obtain an old HP ScanJet 4C, get it running on a PC and put it through its paces. After after nearly five years, three scanners, and untold SCSI cards and drivers later, he finally succeeded. The first big problem was getting a working scanner. These don’t stand up well to shipping, and one arrived with broken mirrors. And when he finally got one that worked, sorting out SCSI controller and driver issues was surprisingly complicated, though ultimately successful.

The HP ScanJet 4C was introduced in 1995, and was notable for its scanning quality, its resolution ( 2400 DPI interpolated / 600 DPI optical ), and selling for under $1000. Except for replacement parts concerns, particularly the customized triphosphor fluorescent bulb assembly, it would still be a very competent scanner today. For this reason, [Shelby] will not be using it as his daily use scanner. Continue reading “Deep Dive Into The HP ScantJet 4C” →