TinyGiant HT68k SBC
May 2, 2007
Last week I picked-up a neat single-board computer from the mid-1980's manufactured by Hawthorne Technologies. This SBC is in a 5-1/4" form factor so it could be bolted to a floppy drive. It's based on an 8MHz 68000 CPU and has a dual serial controller, 256k of RAM and a PC-compatible floppy controller. It came with a floppy-based operating system called K-OS and had an assembler, debugger and Forth language. The setup I got came complete with manuals and disks. The disks include a floppy-based operating system, Forth, a 68000 debugger and a text editor.
The picture shows the memory at the top-left. The WD1770 floppy controller in the upper-right. The 68000 in the lower-left corner (with the ROMs immediately above it). The 68681 dual serial controller is in the lower-right corner. The remaining chip next to the ROMs is the DRAM refresh controller.
The floppy connector is a standard PC-style 0.1" dual-row header (to which I have connected a header-to-card edge adapter). The floppy cable is from a Tandy CoCo disk drive. The power connector for the board is a standard PC floppy connector, so you can use almost any surplus power supply (I'm using one that's 5v/4a and 12v/2a that I got from BG Micro or Marlin P. Jones...I forget which).
The basic specs are: 68000 @ 8MHz, two serial ports, one Centronics parallel port, 128k of RAM (expandable to 512k), an expansion bus and a PC-compatible floppy controller enabling the use of 3.5", 5.25" or 8" drives (OS comes configured for 5.25")...all in a 5.75" x 8" size. The list price was $395 and it came with a ROM monitor, disk-based operating system, assembler and editor. A Forth interpreter was available for an additional $50.
The following are images of the disks. I used Teledisk version 2.16 to make copies of the disks. Teledisk is available here: http://www.classiccmp.org/dunfield/img/teledisk.htm
- K-OS Operating System
- Editor Toolkit
- K-OS Forth
- 68000 Debugger
- MotionBASIC Help System
- ZIP file containing the files from the disks.
Below are scans of the manuals that came with the board:
- TinyGiant 68000 Single Board Computer (system description and schematics)
- K-OS One Operating System (OS manual)
- Editor Toolkit
- 68000 Debugger
I've found a typographical error in one of the manuals. On page 4-5 of the system description manual, there is a pinout of P3 which is the floppy disk drive connector. The disk select pin assignments are wrong:
Pin Old Function Correct Function
6 DS0 DS4
10 DS3 DS1
14 DS1 DS3
There was a newsletter from Hawthorne for this SBC, but I only have a few issues. Here they are:
This is another 68k newsletter, but I don't know much about it (PSM):
Here is another 68k-specific newsletter (PSM):
The Computer Journal (TCJ) Articles
The HT-68K was featured in several articles in TCJ. I don't have the complete series of TCJ, so I might have missed some issues. Here are the ones I could find:
- "68000 Tiny Giant Low Cost 16-bit SBC and Operating System" by Art Carlson (TCJ #27 page 4)
- "68000 - Why use a New OS & the 68000?" by Joe Bartel of Hawthorne Technologies (TCJ #29 page 31)
- "Non-Preemptive Multitasking" by Joe Bartel of Hawthorne Technologies (TCJ #30 page 37)
- "Software Timers for the 68000" by Joe Bartel of Hawthorne Technologies (TCJ #30 page 39)
- "K-OS ONE and the SAGE - Demystifying Operating Systems" by Joe Bartel of Hawthorne Technologies (TCJ #31 page 18)
- "Remote - Designing a Remote System Program" by Al Szymanski (TCJ #31 page 37)
- "Data Structures in FORTH" by Joe and Marla Bartel (TCJ #41 page 9)
- TinyBASIC: I found a copy of Palo Alto Tiny BASIC that was ported to the Motorola Educational Board (MEX68KECB). It should work on this board if the I/O routines are ported and other memory-related things fixed.
The system ROMs were 27128 250nS devices (16k x 8) in a split (high-low) arrangement. The text represents what was written on the EPROM labels.
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Last updated 2021-01-11 19:55 -0500