SBC6120-2
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SBC6120 News
Build a real front panel for your SBC6120! Visit our SBC6120 Builder's Resources Page!
Overview
The SBC6120 can run all standard DEC paper tape software, such as FOCAL-69, with no changes. Simply use the ROM firmware on the SBC6120 to download FOCAL69.BIN from a PC connected to the console port (or use a real ASR-33 and read the real FOCAL-69 paper tape, if you’re so inclined!), start at 2008, and you’re running. OS/278, OS/78 and, yes - OS/8 V3D or V3S - can all be booted on the SBC6120 using either RAM disk or IDE disk as mass storage devices. Since the console interface in the SBC6120 is KL8E compatible and does not use a HD-6121, there is no particular need to use OS/278 and real OS/8 V3D runs perfectly well.
HardwareThe features of the HD-6120 CPU include:
To this the SBC6120 adds:
SoftwareThe 32KW EPROM contains the BTS6120 firmware, which has these features:
Historical NotesAs a historical note, the BTS6120 software started life in 1983 as a bootstrap program for an elaborate Intersil IM6100 system I had planned. The software was developed and tested on a 6100 emulator that I wrote to run on a DECsystem-10, but it never saw any actual hardware. Although I built several simpler 6100 based systems, the one intended for this software proved to be too complex and was never built.
The Model 1 was a useful platform for writing the firmware and device handler to make OS/8 work with the RAM disk, and later for developing and testing the IDE interface and writing the software for that. The Model 1 was too big and clunky, however, and I wanted something that I could fit into a small cabinet along with a hard disk. That, and another few months of designing on weekends and in the evening, gave us the Model 2 that you are reading about now.
LicensingAll SBC6120 files are Copyright (C) 2001-2003 by Spare Time Gizmos.
All SBC6120 software and firmware including, but not limited to, BTS6120, PALX, GAL programming, and the VM01/ID01 handlers, are covered under under the terms of the GNU General Public License. Permission is granted to copy, distribute and/or modify these files under the terms of the GNU General Public License as published by the Free Software Foundation, version 2. In general, these licenses will allow you to use the SBC6120 design for any purpose you choose, including to create derivative works. If you choose to distribute the SBC6120 design or a derivative, then you must make your distribution, including source files, free to anyone.
WARNINGSPARE TIME GIZMOS OFFERS NO WARRANTY, EXPRESS OR IMPLIED, AS TO THE RELIABILITY OR ACCURACY OF THE SBC6120 DESIGN. SPARE TIME GIZMOS OFFERS NO WARRANTY, EXPRESS OR IMPLIED, AS TO THE SUITABILITY OR CORRECTNESS OF ANY SOFTWARE OR FIRMWARE SUPPLIED IN CONJUNCTION WITH THE SBC6120. SPARE TIME GIZMOS MAKES NO REPRESENTATIONS AS TO THE SUITABILITY OF THE SBC6120 FOR ANY APPLICATION. THE ENTIRE RISK AS TO THE USE AND PERFORMANCE OF THE SBC6120 IS ASSUMED SOLELY BY YOU.
LAST BUYWe started selling the SBC6120 in 2002 and the last of the SBC6120 kits was shipped to a customer in France early in 2006. After that the web page was updated to show that the SBC6120 was "sold out". You wouldn't believe the number of emails we started getting after that - apparently, people thought that Spare Time Gizmos would be selling the SBC6120 forever! As much as we'd like to, we just can't do that. The PC boards and 6120 chips are very expensive, and when the orders dwindle to one a month or so it's too much money to keep tied up in inventory. We were persuaded to do one "last buy" of SBC6120 parts, and those parts and PC boards started shipping on July 5th 2006. About 75% of the last buy kits were sold before the parts ever arrived, and as of July 28th 2006, all the last buy kits have been sold out. At the moment, we have no plans to order any more SBC6120 parts or kits.
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The SBC6120 measures just 4.2 inches by 6.2 inches, or roughly the same size
and shape as a standard 3½" disk drive. A four layer PC board with
internal power planes was needed to fit all the parts in this space. A complete
SBC6120 requires just 175mA at 5V to operate, and this requirement can easily be
cut in half by omitting the LED POST code display. Imagine - you can have an
entire PDP-8, running OS/8 from a RAM disk, that’s the size of a paperback
book and runs on less than half a watt!
Never built, that is, until 1999 when I rescued some 6120 parts from a dead
DECmate and decided that, with cheap SRAMs for mass storage and modern GALS
instead of discrete TTL to build a console interface, it was time. That, and
about six weeks of work designing the hardware and laying out the PC board, and
another two months or so of hacking the BTS6120 software to work in this new
environment and the 
All SBC6120 documentation files including, but not limited to, schematics,
Gerber files, and the SBC6120 User's Guide, are covered under the terms of
the GNU 
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