Retrocomputing

1633 Articles

This 68k Board Is About As Simple As It Gets

July 19, 2020 by 15 Comments

For those of us who remember the Motorola 68000 microprocessor, it’s likely that a sizeable quantity of those memories will come in the form of a cream or grey box with a Commodore, Atari, or Apple logo on it These machines were the affordable creative workstations of their day, and under the hood were a tour de force of custom silicon and clever hardware design. We might, therefore, be excused for an association between 68000 based computers and complexity, but in reality, they are as straightforward to interface as the rest of the crop of late-1970s silicon. We can see it in [Matt Sarnoff]’s 68k-nano, about as simple a 68000-based single-board computer as it’s possible to get.

But for all its simplicity, this board is no slouch. It packs a megabyte of RAM, 64k of ROM, a 16550 UART, and an IDE interface for a CompactFlash card. There is also provision for a real-time clock module, through an interesting bit-banged SPI interface from the 16550’s control lines. There appears also to be a 50-pin expansion header.

Software-wise there is a ROM monitor that provides test and housekeeping functions, and which loads an executable from the card plugged into the IDE interface if there is one. This feature makes the board especially interesting, as it opens up the possibility of running a μClinux or similar kernel for a more fully-featured operating system.

The 68k doesn’t receive the attention here that some of its 8-bit contemporaries do, but it still appears from time to time. We’ve certainly featured at least one other 68000-based SBC in the past.

Thanks [Anton] for the tip.

A Z80 Board With Very Few Parts

July 17, 2020 by 25 Comments

The Z80 is one of those old CPUs that is both obtainable and easy to work with — at least in some versions. [Doctor Volt] put together what may be the simplest possible setups to get a working Z80 system. He has the processor, of course. But everything else — clock, memory, and power — are from an Arduino Mega 2560. You could argue that’s two chips, but the board actually has several chips on it. On the other hand, you could probably pull off the same stunt with a bare ATMega 2560.

We’ve seen this done before, but usually with a few more support chips. If you are a purist, [Doctor Volt] also has some Z80 and CP/M experiments where the Arduino only acts as a disk drive for the computer and there are only two support chips. There are three videos for both projects that you can see below.

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A Lowly 8-Bit Micro Busts Copy Protection From The 16-Bit Era

July 16, 2020 by 6 Comments

When floppy disks were the data storage medium of choice, software companies and in particular game developers came up with ever more inventive ways to make them difficult to copy. Tinkering at the edges of the disc format standards didn’t come cheap though, and for example the Dungeon Master game for the Atari ST was reported as using $40,000 worth of custom hardware to achieve its so-called “fuzzy bit” technique. [Chris Evans] set out to recreate it, not by building a modern version of the custom hardware, but by doing it the hard way, with an early-1980s 8-bit BBC Micro home computer.

One could be forgiven for thinking that a computer sporting a 2 MHz 6502 would be unable to manage this task without extra hardware, and were it simply the 6502 itself you would of course be right. So to get anywhere he had to get creative with the Beeb’s built-in peripherals. Eschewing the floppy controller it was hooked up directly to the parallel port, and after a voltage problem courtesy of the drive’s termination resistors we’re taken through some of the 6522 VIA’s different modes in order to achieve a higher speed data burst than would normally be possible. All of these approaches hit the buffers though, until he looks at the 6845 video chip and uses its video output as a very fast shift register. With a custom cable and some work on special video modes, a home computer that would have cost several hundred dollars in the early 1980s can do the work of $40,000 custom hardware from later in the decade. Colour us impressed!

If you’d like to know more about the Dungeon Master copy protection, we’ve been there in the past.

BBC Micro header image: StuartBrady / Public domain.

Soviet Core Memory Experiments

July 14, 2020 by 7 Comments

What do you do when you’ve bought some old Soviet core memory modules on eBay? If you are [CuriousMarc], you wire it up to some test connectors and use your test bench to see if the core memory still works. Spoiler alert: it does.

While it seems crude by today’s standard, there was a time when these memory modules would have been the amazing miniature tech of their day. Each little magnetic torus represents a bit and the modules have 1,024 and 4,096 tiny little donuts strung together in a grid.

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Jerry Lawson biography

Jerry Lawson And The Fairchild Channel F; Father Of The Video Game Cartridge

July 14, 2020 by 14 Comments

The video game console is now a home entertainment hub that pulls in all forms of entertainment via an internet connection, but probably for most readers it was first experienced as an offline device that hooked up to the TV and for which new game software had to be bought as cartridges or for later models, discs. Stepping back through the history of gaming is an unbroken line to the 1970s, but which manufacturer had the first machine whose games could be purchased separately from the console? The answer is not that which first comes to mind, and the story behind its creation doesn’t contain the names you are familiar with today.

The Fairchild Channel F never managed to beat its rival, the Atari 2600, in the hearts of American youngsters so its creator Jerry Lawson isn’t a well-known figure mentioned in the same breath as Atari’s Nolan Bushnell or Apple’s two Steves, but without this now-forgotten console the history of gaming would have been considerably different.

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Modern Mice On Old Computers

July 14, 2020 by 23 Comments

Getting retro hardware up and running again is sometimes a feat, and the amount of effort needed tends to go up exponentially with increased hardware age. Getting an IDE hard drive running again is one thing, but things like peripherals on truly “retro” computers like Commodores and Amigas is another beast altogether if you even have a 30-year-old mouse still lying around. That’s why adapters like Project mouSTer are here to help you connect modern USB hardware to truly ancient computers.

This piece of equipment was built for the Atari ST (hence the name), a 8-bit  computer from the mid-80s. It mates a DB9 plug with USB via a small microcontroller which does the translating. The firmware can be flashed over the USB connection so there’s planned support for other machines of this vintage. The chip supports all the features the original mouse did, too, including PS4 pad support and support for joysticks, and comes in an impressively tiny package once assembled which blends in seamlessly.

The project is a great step to getting retro computers working again, even if you can’t find exact OEM replacements anymore. That’s a common problem, and we’ve seen this solved in other ways for other old Ataris. It’s not uncommon to put modern power supplies in retro computers, either, as long as they power up and work after everything’s wired together.

Changing System Architectures And The Complexities Of Apple’s Butterfly Approach To ISAs

July 13, 2020 by 64 Comments

Apple computers will be moving away from Intel chips to its own ARM-based design. An interesting thing about Apple as a company is that it has never felt the need to tie itself to a particular system architecture or ISA. Whereas a company like Microsoft mostly tied its fortunes to Intel’s x86 architecture, and IBM, Sun, HP and other giants preferred vertical integration, Apple is currently moving towards its fifth system architecture for its computers since the company was formed.

What makes this latest change possibly unique, however, is that instead of Apple relying on an external supplier for CPUs and peripheral ICs, they are now targeting a vertical integration approach. Although the ARM ISA is licensed to Apple by Arm Holdings, the ‘Apple Silicon’ design that is used in Apple’s ARM processors is their own, produced by Apple’s own engineers and produced by foundries at the behest of Apple.

In this article I would like to take a look back at Apple’s architectural decisions over the decades and how they made Apple’s move towards vertical integration practically a certainty.

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