I decided to build a gateway that would allow the Alto to communicate with a modern system. The gateway would communicate with the Alto using its obsolete 3Mb/s Ethernet, but could also communicate with the outside world. This would let us network boot the Alto, transfer files to and from the Alto and backup disks. I expected this project to take a few weeks, but it ended up taking a year.
Steve Chamberlin over at Big Mess o’Wires has been working on an FPGA-based disk controller for Apple II, which he call Yellowstone:
Apple II disk controller cards are weird, there are a crazy number of different types, and many are rare and expensive. Can an FPGA-based solution save the day for retro collectors? You bet! Nearly all the existing disk controllers connect the same 8-bit bus to the same 19-pin disk interface, so a universal clone is merely a question of replacing the vintage 80s guts of the card with a modern reprogrammable FPGA. This hypothetical universal controller card could connect to almost any Apple II disk drive, or a Floppy Emu. Here’s my first attempt.
Ken Shirriff wrote a great article describing the repair process of the vintage IBM 1401 mainframe computer:
The problem started when the machine was powered up at the same time someone shut down the main power, apparently causing some sort of destructive power transient. The computer’s core memory completely stopped working, making the computer unusable. To fix this we had to delve into the depths of the computer’s core memory circuitry and the power supplies.
In this video, I decided to upgrade my home built PC from AdLib sound to MIDI. I tried out a couple different midi modules, the Roland MT-32 and the Roland SC-55. I learned that I’d need an MPU-401 or compatible ISA interface, and I explored the alternatives, eventually settling on the HardMPU by Ab0tj. Using the HardMPU schematic, I built a board, programmed the microcontroller, and tried out Vintage games on my Xi 8088. I also wrote my own Midi player to play .MID files using MPU-401 intelligent mode.
I’ve been restoring a Xerox Alto minicomputer from the 1970s and figured it would be interesting to see if it could mine bitcoins. I coded up the necessary hash algorithm in BCPL (the old programming language used by the Alto) and found that although the mining algorithm ran, the Alto was so slow that it would take many times the lifetime of the universe to successfully mine bitcoins.
The Alto was a revolutionary computer designed at Xerox PARC in 1973 to investigate personal computing. It introduced high-resolution bitmapped displays, the GUI, Ethernet and laser printers to the world, among other things. In the photo above, the Alto computer is in the lower cabinet. The black box is the 2.5 megabyte disk drive. The Alto’s unusual portrait display and an early optical mouse are on top.
See the full post and more details on his blog, righto.com.
Kai Bader writes, “I’m currently working on a custom development board, based on a quarter of a century old microprocessor, the Sharp LH5801. This microprocessor is the heart of the Sharp PC-1500(A) Pocket Computer, also known as Tandy TRS-80 Model II.”
Recently my friend Bill, N2CQR posted data on his blog ~ soldersmoke.blogspot.com about a vintage late 1950’s early 1960’s 10 milliwatt 10 Meter transmitter. That was quite a feat!
But given my Italian heritage I could not let that pass without building my own solid state transmitter using a transistor from 1955. My rig operates on 14.060 and produces 0.4 milliwatts with a 3 volt collector supply using a Germanium transistor from Philco. The SB-100 was one of the first RF transistors that could work all the way past the 10 Meter band. The max Pout was 10 milliwatts –so mine is just loafing along.
This thing was sold for parts and repair since the seller did not think it was working. As it turned out, everything worked just fine, but not in an expected way. This is not your typical calculator, but rather a teaching one.