Actions

Category

Retrocomputing

From Trammell Hudson's Projects

Retrocomputing

I really enjoy working on ancient machines and have restored several antiques to mostly operational condition. Many of my other projects involve adapting modern computers to fit inside or work with older hardware.

More photos of antique computers, some of which I'm working on restoring.

PDP-11/34

PDP-11/34 on display

We rescued two PDP-11/34 computers and their associated equipment from a storage unit in the Bronx and have been working on getting one of them running again. It is now on static display at my office. Read on for more details...


ADVENT.FOR

GET LAMP

This is a transcript of how to setup simh on a simulated PDP-11, generate a working FORTRAN IV compiler, transfer the original ADVENT source code into the simulator or real PDP-11 hardware, build it and play Colossal Cave Adventure. Read on for the details...

Kaypro 2

Kaypro2 Wikipedia page

There was a Kaypro 2 in the storage loft at NYCR that booted on the first try. The floppy disk in the drive was "Mickey's Jigsaw Puzzles", but it booted up with CP/M. On the disk was KERM411.COM, which allowed us to connect it to a remote Unix machine. Read on for the details...

Altair 8800b

MITS Altair 8800b

We ended up with a stack of Altair 8800b systems from MITS and "Cyclone" clones of the Altair, as well as a stack of ROM chips. I haven't had time to go through and survey them yet. Read on...

NeXT Computers

NeXT OmniWeb

The NeXT computers were one of Steve Job's greatest systems. They developed the Objective C language, the Interface Builder things like the Terminal.app application packaging. When Apple bought NeXT, it dumped the older Macintosh OS and turned the user friendly (but still Unix-like) NeXTstep into OS X. Every Mac and iPhone today still remembers this with the name of the classes like NSString in Foundation Kit. Read on for setup details...


45baud.net

45baud.net banner

I used to maintain a separate wiki dedicated to teletypes, punchcards and papertape machines at 45baud.net, although I've migrated most of the information onto this website instead.


Reimplementing

Sometimes when the systems are no longer functional or worth restoring, I'll re-implement parts of them or "re-brain" them with modern CPUs.


TRS80 Model 100 + Pi

TRS80 + Teensy
TRS-80 Model 100 motherboard versus Teensy++ version

The TRS80 Model 100 was the very first tablet computer and many of them are still functional. Using the original 1983 schematics and datasheets, I've designed a new motherboard to replace the 80C85 with a Teensy++ and Raspberry Pi. Read on for more information on interfacing with the Model 100...


Mac SE Easter Egg

Mac SE engineers (0x1D93C)
Mac SE

Using my PROMdate generic EPROM reader, I extracted the Mac SE boot ROMs from a machine I found on the side of the road. We then reverse engineered the easter egg photographs of the development team hidden in the extra space. Read on for more details...


Macintosh SE Video interface

Mac SE video pulses
Mac SE video driving success

Rather than let an old Mac SE with dead drives go to waste, I built a video card interface to the BeagleBone Black to drive the 512x342x1 display using the PRU. The bit clock is 16 MHz, about 64ns per bit, which is easily doable with programmable realtime unit, but not from userspace due to the hard realtime constraints -- a few nanosecond delay in generating the video signal causes visible distortion. The source is github.com/osresearch/classicmac and reuses the PRU interface from LEDscape / Octoscroller. See it in action! Or read on for more info...


ADB to USB adapter

Mac SE with a BeagleBone Black motherboard

Older Macintosh computers used the Apple Desktop Bus protocol to communicate with keyboards and mice. It is a one-wire, bidirectional multi-drop protocol. More information on my adapter design


Unibus Adapter

Beagle Bone Black + Unibus

I'm building an adapter from the BeagleBone Black to the DEC Unibus to allow modern CPUs to interface with Unibus devices, or to emulate other devices on the bus, like a network adapter for our PDP-11. There are 56 signals on the bus and the BBB has 55 user GPIO lines, but the DCLO line isn't really necessary since by the time it is asserted it is too late to do anything about it. Read on for more details...

Punch cards and paper tape

IBM Model 129 Card Data Recorder

IBM 129 Card Data Recorder
Rear of cardpunch

We restored this IBM 129 Card data recorder to an almost fully functional state and can punch cards fairly reliably now. The circuits are wirewrapped and also feature some of the earliest integrated components. Read on for more info on the IBM 129 Card Data Recorder


IBM 83 Card Sorter

IBM 83 card sorter
IBM 83 card sorter, vacuum tubes working

This stately IBM 83 Card Sorter is still a work in progress. I can manually crank the cards through it, but the tubes and motor drive do not seem to be functioning. Read on for more details about this device...


Papertapes

DEC papertape library
Papertape reader

I ran across a cache of mid 1960's papertapes and read them with a friend's Model ASR33 Teletype, and then helped another friend build an LED punch tape reader to read some of the 8-bit tapes that didn't read in the 7-bit teletype. More details on the papertapes.


Terminals

Model 15 Teletype

Model 15 front view
Teletype Model 15 USB interface board

To drive a 1930's Model 15 Teletype, I've designed a USB serial port and 100VDC, 60mA current loop boost converter. It converts the ASCII to 5-bit Baudot at 45.5 Baud and generates the high voltage to operate the selector coil. Read on for more details...

Model ASR33 Teletype

ASR33 teletype printing a calendar
ASR33 with top cover removed

A friend of mine has an excellent condition Teletype Model 33 ASR that I've built an 110 baud 7-bit current loop adapter with an auto-on power relay. We've used it to read paper tapes and as a serial console for a Raspberry Pi. The bit encoding and timing is purely mechanical with a rotor very reminscent of the forty year older Model 15 Teletype. Read on for more details...

DEC VT100

DEC VT100
DEC VT100

We have a few functional VT100s and a stack of broken ones awaiting fixes. Some of them are connected to a BeagleBone running Linux, some of them are connected to a PDP-11/34. Read on for more info on fixing the terminals...

Symbolics keyboard to USB interface

Symbolics keyboard

If you want to connect your Symbolics Lisp machine's keyboard to your more modern recent system, you need to convert it to USB. The interface is quite simple: it looks like a 128-bit shift register with one bit per key on the keyboard. There does not appear to be any ghosting, which means N-key roll over is not an issue! Read on for more details...


Events

Vintage Computer Festival East 8.0

HP 2647A terminal and 100 E-Series

Over a weekend in 2012 a bunch of NYCR members went to the Vintage Computer Festival East (8.0), held at the InfoAge / MARCH computer history museum in Wall, NJ. Read on for more photos from the musuem...