Inside A DEC Hard Drive

A lot of technology from the not-so-distant past doesn’t resemble modern versions very much. For a case in point, look at the DEC RS08 disk drive meant to pair with a circa 1970 PDP-8. Paired with an RF08 controller, this was state of the art, holding 262K 12-bit words with a blistering access speed of almost 63K/second unless you were plugged into 50Hz AC when it was closer to 50K/second. [Uniservo] had the disk unit, but not the controller. Someone else had a controller, but no disk drive. So [Uniservo] is shipping the disk to its new owner in a move worthy of a Reeses’ Peanutbutter Cup. The problem? The disk is super fragile and shipping is risky, so he decided to remove the platter for separate packing. Good thing for us, because we get a peek inside.

The nickel-cobalt platter looks like a thick LP record with heads underneath. As you might guess from the data transfer specification, the motor was just a common AC motor that rotated the platter against the head.

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Miniature Faux Floppy For 8-Bit Atari Looks The Part

There’s plenty of fun to be had with retrocomputers of yesteryear, but for modern users, it can be something of a culture shock. Going back to floppy disks after all these years is a reminder of just how far storage technology has come in terms of speed, reliability, and of course, capacity. Luckily, there are ways to combine the best of both worlds.

Floppy drive emulators for classic computers are of course nothing new, but we think this one [c0pperdragon] has put together is worthy of a closer look. Not only does the ATmega32U4 based emulator have an exceptionally low part count, but the code has been written in the Arduino IDE. Both features make it easy for new players to duplicate and revise the design should they feel so inclined. In a pinch you could even implement it on a breadboard with a garden variety Arduino.

The emulator is housed in a 3D printed enclosure designed to look like an era-appropriate Atari 1050 Disk Drive, except you’re using SD cards instead of floppies. The firmware can mimic two physical drives and supports up to 100 disk images on each SD card. The user interface is about as simple as it gets, with two push buttons and a pair of seven-segment LEDs to indicate which disk image is currently loaded up.

We’ve seen some very elaborate disk emulators over the years, but there’s something compelling about how straightforward this version is. If it helps a few more people experience the unique joys of retrocomputing, it’s a win in our book.

Cutest Possible Atari Disk Drive

[rossumur]’s first computer was an Atari 400, and after riding a wave of nostalgia and forgetting the horrible keyboard found in the Atari 400, he decided it was time to miniaturize the venerable Atari 810 disk drive by putting an entire library of Atari games on a single microSD card.

SD cards have been slowly but surely replacing disk drives for just about every old computer system out there. You no longer need 400k disks for your old mac, and your Commodore 64 can run directly off an SD card. The Atari 8-bits have been somewhat forgotten in this movement towards modern solid state storage, and although a solution does exist, this implementation is a pretty pricey piece of hardware.

[rossumur]’s hardware for giving the Atari 8-bit computers an SD card slot is just one chip – an LPC1114 ARM Cortex M0. This, along with an SD card slot, 3.3V regulator, a LED and some caps allows the Atari to talk to SD card and hold the entire 8-bit Atari library on a piece of plastic the size of a fingernail.

Designing a circuit board doesn’t have the street cred it once did, and to give his project a little more pizzazz he chose to emulate the look of the very popular miniaturized Commodore 1541 disk drive with a tiny replica of the Atari 810 disk drive. This enclosure was printed at Shapeways, and with some enamel hobby paint, [rossumur] had a tiny, tiny 810 drive.

While this build does require the sacrifice of a somewhat rare and certainly old Atari SIO cable, it is by far the best solution yet seen for bringing a massive game library to the oft-forgotten Atari 8-bit home computers.

Thanks [lucas] for the tip.

A DiskVaccuum For Obsolete Disk Formats

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[Jim] has a box of disks for a very old Compucolor II computer, and with bit rot slowly setting in he figured it might be time to dump all those disks to a more permanent format. After reviewing the existing tools to read these disks, he decided to build his own floppy disk interface that he calls the DiskVaccuum.

The DiskVaccuum is based on a Papilio Pro FPGA board and a few chips worth of level conversion. The FPGA is able to read bits and move the head of the disk with ease, saving everything to the drive of a much more modern computer.

On the USB side of the Papilio board, [Jim] wrote a shell of sorts in Python to capture tracks on the disk, read out the track listing, save an image file, and do all the things a proper DOS should. Right now the project is only for the Compucolor II disk drive, but [Jim] played around with KiCAD enough to create a Papilio-to-disk-drive interface board with connectors for most of the disk drives of this particular vintage. The hope is to generalize the hardware and software to read disks for other systems, including those with 8-inch drives.

[Jim] put up a video describing the hardware and demoing his Python capture utility. You can check that out below.

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Pocket Serial Host Acts As An Apple II Disk Drive

apple-II-pocket-serial-host

[Osgeld] is showing off what he calls a sanity check. It’s the first non-breadboard version of his Pocket Serial Host. He’s been working on the project as a way to simplify getting programs onto the Apple II he has on his “retro bench”. When plugged in, the computer sees it as a disk drive.

The storage is provided by an SD card which is hidden on the underside of that protoboard. This makes it dead simple to hack away at your programs using a modern computer, then transfer them over to the retro hardware. The components used (starting at the far side of the board) are a DB9 serial connector next to a level converter to make it talk to the ATmega328 chip being pointed at with a tool. The chip below that is a level converter to get the microcontroller talking to the RTC chip seen to the right. The battery keeps that clock running when there’s no power from the 5V and 3.3V regulators mounted in the upper right.

The video after the break shows off this prototype, the breadboard circuit, and a demonstration with the Apple II.

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