Retrocomputing

1437 Articles

How To Use That Slide Rule

November 21, 2025 by 30 Comments

You have that slide rule in the back of the closet. Maybe it was from your college days. Maybe it was your Dad’s. Honestly. Do you know how to use it? Really? All the scales? That’s what we thought. [Amen Zwa, Esq.] not only tells you how slide rules came about, but also how to use many of the common scales. You can also see his collection and notes on being a casual slide rule collector and even a few maintenance tips.

The idea behind these computing devices is devilishly simple. It is well known that you can reduce a multiplication operation to addition if you have a table of logarithms. You simply take the log of both operands and add them. Then you do a reverse lookup in the table to get the answer.

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Commodore’s Most Popular Computer Gets DOOM-style Shooter

November 21, 2025 by 45 Comments

When people talk about the lack of a DOOM being the doom Commodore home computers, they aren’t talking about the C64, which was deep into obsolescence when demon-slaying suddenly became the minimal requirement for all computing devices. That didn’t stop [Kamil Wolnikowski] and [Piotr Kózka] from hacking together Grey a ray-cast first-person shooter for the Commodore 64.

Grey bares more than a passing resemblance to id-software’s most-ported project. It apparently runs at 16 frames per second on a vanilla C64 — no super CPU required. The secret to the speedy game play is the engine’s clever use of the system’s color mapping functionality: updating color maps is faster than redrawing the screen. Yeah, that makes for rather “blockier” graphics than DOOM, but this is running on a Commodore 64, not a 386 with 4 MB of RAM. Allowances must be made. Come to think of it, we don’t recall DOOM running this smooth on the minimum required hardware — check out the demo video below and let us know what you think.

The four-level demo currently available is about 175 kB, which certainly seems within the realms of possibility for disk games using the trusty 1541. Of course nowadays we do have easier ways to get games onto our vintage computers.

If you’re thinking about Commodore’s other home computer, it did eventually get a DOOM-clone. Continue reading “Commodore’s Most Popular Computer Gets DOOM-style Shooter” →

A Paper Caper: The Hole Data

November 20, 2025 by 26 Comments

Since the dawn of computers, we’ve tried different ways to store data. These days, you grab data over the network, but you probably remember using optical disks, floppies, or, more recently, flash drives to load something into your computer. Old computers had to use a variety of methods, such as magnetic tape. But many early computers used some technology that existed from the pre-computer era, like punched cards or, as [Anthony Francis-Jones] shows us, paper tape.

Paper tape was common in TeleType machines and some industrial applications. In fact, as early as 1725, looms could use paper tape, which would eventually lead to punched cards. For computers, there were two common variations that differed in how many holes were punched across the tape: 5 or 8. There was also a small sprocket hole that allowed a gear to move the tape forward through a reader.

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[Usagi Electric] and his home brew computer

TMS9900-based Home Brew Computer

November 17, 2025 by 3 Comments

[Usagi Electric] is known for minicomputers, but in a recent video, he shows off his TMS9900-based homebrew computer. The TMS9900 CPU was an early 16-bit CPU famously used in the old TI-99/4A computer, but as the video points out, it wasn’t put to particularly good use in the TI-99/4A because its RAM was hidden behind an inefficient interface and it didn’t leverage its 16-bit address space.

The plan is for this computer to have 2K words of ROM, 6K words of RAM, and three serial lines: one for the console terminal, another for a second user console terminal, and the third for access to a tape drive.

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Supersized Calculator Brings The Whole Intel 4004 Gang Together

November 16, 2025 by 23 Comments

Though mobile devices and Apple Silicon have seen ARM-64 explode across the world, there’s still decent odds you’re reading this on a device with an x86 processor — the direct descendant of the world’s first civilian microprocessor, the Intel 4004. The 4004 wasn’t much good on its own, however, which is why [Klaus Scheffler] and [Lajos Kintli] have produced super-sized discrete chips of the 4001 ROM, 4002 RAM, and 4003 shift register to replicate a 1970s calculator at 10x the size and double the speed, all in time for the 4004’s 50th anniversary.

We featured this project a couple of years back, when it was just a lonely microprocessor. Adding the other MSC-4 series chips enabled the pair to faithfully reproduce the logic of a Busicom 141-PF calculator, the very first to market with Intel’s now-legendary microprocessor. Indeed, this calculator is the raison d’etre for the 4004: Busicom commissioned the whole Micro-Computer System 4-bit (MCS-4) set of chips specifically for this calculator. Only later, once they realized what they had made, did Intel buy the rights back from the Japanese calculator company, and the rest, as they say, is history.

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The Fastest (68k) Macintosh Might Not Be An Amiga Anymore

November 15, 2025 by 19 Comments

Amiga and Atari fans used to lord over their Apple-eating brethren the fact that Cupertino never moved to the most advanced 68k processors — so for a while, thanks to 68060 accelerator cards, the fastest thing running Macintosh software was an Amiga (or Atari). After all these years, the Macintosh community is finally getting the last laugh, as [zigzagjoe] demonstrates an actual Macintosh booting with a 68060 CPU for the first time in a thread on 68KMLA. Video or it didn’t happen? Check it out below.

The Mac in question is a Quadra 650, which is a good choice since it was about the last thing Apple sold before switching to PowerPC, and ran the 68040 processor. [Reinauer] had already produced a 68040-to-68060 socket adapter (the two chips not being pinout compatible), so the hardware part of the battle was already set. Software, however? That was a different story, and where [zigzagjoe] put in the effort.

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2025 Component Abuse Challenge: The VIA Makes Noise, Again

November 14, 2025 by 3 Comments

In the days of 8-bit home computing, the more fancy machines had sound chips containing complete synthesizers, while budget machines made do with simple output ports connected to a speaker — if they had anything at all. [Normal User] appears to be chasing the later route, making PCM sound by abusing the serial port on a 6522 VIA chip.

A serial port is when you think about it, a special case of a one-bit output port. It’s designed for byte data communication but it can also carry a PCM data stream. We’ve seen this used with microcontrollers and peripherals such as the I2S port plenty of times here at Hackaday, to produce such things as NTSC video. The 1970s-spec equivalent might not be as fast as its modern equivalent, but it’s capable of delivering audio at some level. The machine in question is a Ben Eater breadboard 6502 with a World’s Worst Video Card, and as you can hear in the video below the break, it’s not doing a bad job for the era,

If you think this hack sounds a little familiar then in a sense you’re right, because Ben Eater himself made noises with a 6522. However it differs from that in that he used the on-board timers instead. After all, the “V” in “VIA” stands for “versatile”.

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