Retrocomputing

1635 Articles

The OS/2 Operating System Didn’t Die… It Went Underground

June 20, 2019 by 72 Comments

One problem with building things using state-of-the-art techniques is that sometimes those that look like they will be “the next big thing” turn out to be dead ends. Next thing you know, that hot new part or piece of software is hard to get or unmaintained. This is especially true if you are building something with a long life span. A case in point is the New York City subway system. Back in the 1990s the transit authority decided to adopt IBM’s new OS/2 operating system. Why not? It was robust and we used to always say “no one ever got fired for buying IBM.”

There was one problem. OS/2 was completely eclipsed by other operating systems, notably Windows and — mostly — has sunk from the public view. [Andrew Egan’s] post covers just how the conversion to a card-based system pushed OS/2 underground all over the Big Apple, and it is an interesting read.

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Reverse Engineering The Sound Blaster

June 19, 2019 by 42 Comments

The first sound card to output PCM audio — the kind you need for audio samples — wasn’t the Sound Blaster. The AdLib Music Synthesizer Card could output PCM audio over software. The AdLib card also cost $200 at the time of its release. This was too much for some, and in time the Creative Labs Sound Blaster was released for the rock-bottom price of $125. This was a more capable card, and in the years since prices on the used market have gone through the roof. In 1990, you could buy a Sound Blaster for a Benjamin and a half, in 2019, prices on eBay are reaching and exceeding $400.

With the prices of used cards so high, we start to get into the territory where it starts to make sense to reverse engineer and re-manufacture the entire card. This hasn’t been done before, but that’s no matter for [Eric Schlaepfer], or [@TubeTimeUS]; he’s done crazier projects before, and this one is no different.

In reverse-engineering the Sound Blaster, there are a few necessary components. The Sound Blaster had an OPL2 chip for sound synthesis, which you can get through various vendors. The trick, though, is the microcontroller. This is really just an 8051 with a custom mask ROM.

The goal of this project is actually just to dump the ROM on the Intel 8051-alike microcontroller. This is something that’s relatively commonly done in high-tech labs, and luckily the Bay Area has [John McMaster], the guy who will take you into his lab and strip a die from its epoxy. Looking at the chip under the microscope, it was discovered the mask ROM on this chip was an implant ROM, with the ones and zeros represented by invisible ions in the substrate itself. There was no hope of reverse-engineering this chip from a purely visual inspection, but there was a sense amplifier on one of the data lines. By probing this sense amplifier while running through the address space, [Eric] was able to dump all the bytes of the ROM one bit at a time.

However, and there’s always a however, there are clone Sound Blasters out there, usually from China, and you can dump these chips if you’re lucky enough to get your hands on one. [Eric] reached out to the community and found these clone microcontrollers didn’t have the code protect bit set; dumping these was easy. This ROM was compared to the work [Eric] did with the sense amplifier, and after figuring out the order of the bits, it was found the code matched. The code was successfully cloned, and now new Sound Blasters can be made. Don’t tell eBay that, because someone is trying to sell one of [Eric]’s clone cards for $180.

All the code, files, materials, and everything needed to clone a Sound Blaster can be found in [Eric]’s GitHub, although there are a few open questions as to what’s going on in the Sound Blaster’s microcontroller. There’s a ‘secret’ 512-byte ROM on the die, and no one outside of an Intel NDA knows what it does. This could be used for a manufacturing test, but who knows. Other than that, there are a few features in the code that weren’t used, like previously unknown DSP commands, an ADPCM lookup table, and a routine that plays from SRAM without using DMA. It’s a deep dive into the inner workings of the most popular sound card of all time, and it’s quite simply amazing.

A Faithful Replica Of An Early Computer Trainer

June 17, 2019 by 11 Comments

Turn the clock back six decades or so and imagine you’re in the nascent computer business. You know your product has immense value, but only to a limited customer base with the means to afford such devices and the ability to understand them and put them to use. You know that the market will eventually saturate unless you can create a self-sustaining computer culture. But how does one accomplish such a thing in 1961?

Enter the Minivac 601. The brainchild of no less a computer luminary than Claude Shannon, the father of information theory, the Minivac 601 was ostensibly a toy in the vein of the “100-in-1” electronics kits that would appear later. It used electromechanical circuits to teach basic logic, and now [Mike Gardi] has created a replica of the original Minivac 601.

Both the original and the replica use relays as logic switches, which can be wired in various configurations through jumpers. [Mike]’s version is as faithful to the original as possible with modern parts, and gets an extra authenticity boost through the use of 3D-printed panels and a laser-cut wood frame to recreate the look of the original. Sadly, the unique motorized rotary switch, used for both input and output on the original, has yet to be fully implemented on the replica. But everything else is spot on, and the vintage look is great. Extra points to [Mike] for laboriously recreating the original programming terminals with solder lugs and brass eyelets.

We love seeing this retro replica, and appreciate the chance to reflect on the genius of its inventor. Our profile of Claude Shannon is a great place to start learning about his other contributions to computer science. We’ve also got a deeper dive into information theory for the curious.

Thanks to [Granz] for the tip.

Back To Where (For Most Of Us) It Started, The Intel 8080

June 15, 2019 by 42 Comments

The early history of microprocessors is a surprisingly complex one, with more than one claimant for the prize of being the first, and multiple competing families. That the first commercially available part was the Intel 4004 is a matter of record, but it’s fair to say that few of us will have ever encountered one. Even its 8-bit sibling the 8008 would not have featured heavily in a 1974 version of Hackaday, such was its exotic nature. If there’s a microprocessor that can be claimed to have started it all for us then, it’s the Intel 8080. It established the 8-bit microporcessor with an 8-bit bus and a 16-bit address space, it had an order of maginitude more performance than its predecessors, and crucially it would become affordable enough for experimenters. It provided the guts of the MITS Altair 8800 microcomputer, and thus kickstarted the progression of home computers which led to the devices you use every day.

The 8080 is in our sights today, thanks to [DeviceGuru], who was sent down memory lane by thoughts of the 6502-based KIM-1 from his master’s thesis project. This led to memories of the 8080 Abie computer that he built for himself in 1979, for which he provides us some details and hand-drawn schematics. By then the 8080’s need for several support chips made it somewhat outdated, but from his perspective the chip could be had from Radio Shack without too much outlay. His tale of hand-assembling 8080 code and sending it to a friend for blowing onto a PROM might be familiar to some readers of a certain age.

Though the 8080 ceased volume production a quarter century ago (surprisingly there are still places you can get a new one though) it hasn’t entirely disappeared from our community’s consciousness. [DeviceGuru] tells us about the 8080 Microprocessor kit from [Wichit Sirichote] in Thailand which is a single board computer in the 1970s vein, hex keypad and all.

As you might expect, the 8080 hasn’t appeared in many projects here due to its rarity. Those that have seem more likely to feature its Eastern Bloc clones, such as this Polish model or this Russian one. It’s worth the reminder that if you fancy exploring some 8080 code of your own that you don’t even need an 8080 to run it on some silicon. The hugely popular Zilog Z80 as found in retrocomputers such as the RC2014 is fully mostly 8080 code compatible, indeed some of us learned about microprocessors that way because 8080 books were discounted in 1983 and Z80 ones weren’t.

Header image: Konstantin Lanzet [CC BY-SA 3.0].

Vintage Speech Synthesizer Croons The Oldies

June 11, 2019 by 33 Comments

If you listened to the National Weather Service Weather Radio in the US about 25 years ago, you’ll no doubt remember [Perfect Paul], one of the synthesized voices used to read current conditions and weather forecasts. The voice came from a DECtalk DTC01, a not inexpensive voice synthesizer first made in 1984 that also gave voice to [Stephen Hawking] for many years.

Long obsolete, the DECtalk boxes have a devoted following with hobbyists who like to stretch what the device can do. Some even like to make it sing, after a fashion, and [Michael] decided that making a DECtalk sing “Xanadu”, the theme song from the 1980 [Olivia Newton-John] musical extravaganza, was a good idea. Whether it actually was is debatable, and we’ll take exception with having that particular ditty stuck in our head as a result, but we don’t judge except on the merits of the hack.

It’s actually easy if you have a DECtalk; the song is a straight ASCII file with remarkably concise instructions on which phonemes the box needs to generate. Along with inflection, tone, and timing instructions, the text file looks almost completely unlike English while still somehow being readable. The DECtalk accepts the file over RS-232, which would be easy enough to do with a modern computer, but [Michael] upped his game a bit by using a TRS-80 Model 100 computer as a serial terminal. The synthesized song is in the video below, with the original included for reference by those who didn’t experience endure the late disco-era glory days.

DECtalks seem pretty rare in the wild, so we appreciate this glimpse at what they can do. There are other retro speech synthesizer hacks, though: the simulated walnut goodness of the Votrax and the MicroVox come to mind, as does the venerable TI Speak and Spell.

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Homebrew Laptop Makes A Statement With A Steampunk Theme

June 9, 2019 by 15 Comments

Some may argue, but your choice of computing hardware says exactly zero about you, at least when you buy off the shelf. Your laptop or PC is only one of millions, and the chances of seeing someone with the exact same machine are pretty good. If you want to be different, you really need to build something yourself.

This homebrew steampunk laptop does a great job at standing out from the crowd. [Starhawk]’s build is an homage to the Steampunk genre, in a wooden case with brass bits and bobs adorning. The guts are based on an Intel motherboard, a bit dated but serviceable enough for the job. There’s a touch-capable LCD in the lid, and we absolutely love the look of the keyboard with its retro-style chrome and phenolic keycaps. Exposed USB cables run to and fro, and the braided jackets contribute to the old-timey look. The copier roller as a lid hinge is a nice touch too.

[Starhawk]’s build log is long and detailed, and covers the entire build. We’ve seen interesting builds from him before, like this junk-bin PC build for a friend in need. Looks like this one is for personal use, though, and we can’t blame him.

1980s Plotter Plays Flappy Bird

June 8, 2019 by 5 Comments

Should you happen to have an HP7440A or similar plotter hanging around, you could have a quick game of Flappy Bird — or Plotty Bird as [WesleyAC] calls it. Just be sure you have some blank paper. The whole thing fits in about 200 lines of Rust code and — according to the author — gets to about 20 frames per second.

Watching the thing go, it appears that it draws a random set of pipes and then traces your flight path on the same page in real time.

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