New Board Development - SBC6120-RBC Edition [message #454] |
Thu, 07 April 2016 21:27  |
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Andrew B
Messages: 467 Registered: October 2015 Location: Near Redmond, WA
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All - I'm happy to announce the development of a new RBC SBC board, the SBC6120-RBC Edition
This is a re-layout of the Spare Time Gizmos SBC6120 into a 2-layer board routed in KiCAD.
I have setup a page for it on the Wiki here - SBC6120-RBC Edition
For those who aren't familiar with the SBC6120, it is a single board computer using the Harris HD-6120 "PDP-8 on a chip" which can be used to run vintage DEC software such as OS/8, FOCAL, and of course, Adventure! Robert Armstrong of Spare Time Gizmos licensed the design files under the GNU FDL and the software under the GPL, so I've taken advantage of that to create a new version of this workhorse board.
Right now I have a "minimum changes" version of the board already routed in FreeRouter. I've:
*Re-routed the board as a 2-layer board, with double-width traces for VCC and GND and flood-fills for VCC and GND on the top and bottom of the board.
*Added a jumper which allows either 27C256 EPROMS (original design) or 28C256 EEPROMs to be used (one of the address pins goes to a different location on the two chips).
*Made some slight changes to the POST display to allow standard rectangular LEDs to be used, and a slightly different reset switch.
*Tweaked a few locations of things to make the new silkscreens look better.
Everything else is unchanged from the original design.
Are there any other changes anyone would suggest before I go to prototypes on this?
[Updated on: Thu, 07 April 2016 21:28] Report message to a moderator
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Re: New Board Development - SBC6120-RBC Edition [message #470 is a reply to message #469] |
Mon, 11 April 2016 08:03   |
gkaufman
Messages: 186 Registered: October 2015
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Senior Member |
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Fantastic!
I should have all parts waiting here for construction. (Just saw new diagrams on the Wiki, using 128Kx8's)
As a follow up project, might be neat to have a S-100 "carrier" board with a simplified front panel that the SBC6120-RBC can piggy-back onto 
- Gary
Andrew B wrote on Sun, 10 April 2016 22:04The 5 prototype boards are spoken for at this point:
Me
Gary (has original STG board as well)
Wayne (has original STG board as well)
John C.
1 gentleman from the Spare Time Gizmos group who contributed a fixed Gerber of the original board to help get this done.
Should be about 2 weeks to get them in.
I am really glad to get this board re-captured into an open source EDA program and available for other hobbyists. It's a very well thought out design and the BTS6120 monitor ROM is very powerful!
[Updated on: Mon, 11 April 2016 12:13] Report message to a moderator
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Re: New Board Development - SBC6120-RBC Edition [message #472 is a reply to message #469] |
Tue, 12 April 2016 11:54   |
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Wayne W
Messages: 385 Registered: October 2015 Location: Fallbrook, California, US...
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Senior Member |
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Andrew B wrote on Sun, 10 April 2016 22:04The 5 prototype boards are spoken for at this point:
Me
Gary (has original STG board as well)
Wayne (has original STG board as well)
John C.
1 gentleman from the Spare Time Gizmos group who contributed a fixed Gerber of the original board to help get this done.
Should be about 2 weeks to get them in.
I am really glad to get this board re-captured into an open source EDA program and available for other hobbyists. It's a very well thought out design and the BTS6120 monitor ROM is very powerful!
Sounds great Andrew. I have a couple of spare HD6120 already, so I am good on the hardest to procure part. I will review the rest of the parts list shortly and try to get everything ahead of the board's arrival.
As I reviewed the state of my previous build, the one point of frustration for me was the ROM versions. Based on email's from Bob Armstrong, the latest ROM version is 271 (ignoring a branch of ROM version for the -RC hardware version which is not relevant). However, the only ROM version source/hex files I have ever found are 266. I asked for the latest version on the SpareTimeGizmos Yahoo! Forum some time ago, but radio silence. If you have any contacts that might be able to get us the latest version, that would be very nice. Not a show-stopper since v266 should be quite functional.
-Wayne
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Re: New Board Development - SBC6120-RBC Edition [message #474 is a reply to message #472] |
Tue, 12 April 2016 12:04   |
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Andrew B
Messages: 467 Registered: October 2015 Location: Near Redmond, WA
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Senior Member Administrator |
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My plan is to get a working board and then ask about the source code for v271. Another person (Jim Kearney who designed the IOB6120) contributed code to the monitor ROM at one point and his code is licensed under the GPL, so the source code for the later versions should be made available to anyone who received a binary versions in the ROM.......
v271 fixed some bugs in the fron panel switches/rotary knob, so it would be nice to have that version. Otherwise we'll need to start from v266 and re-create the fixes.
But I think once we have working boards, it's very likely I'll be able to get us a copy of the source.
I'd be hesitant to upload the binary version to the wiki without the source due to the GPLed code.
[Updated on: Tue, 12 April 2016 12:05] Report message to a moderator
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Re: New Board Development - SBC6120-RBC Edition [message #479 is a reply to message #478] |
Tue, 12 April 2016 15:38   |
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Andrew B
Messages: 467 Registered: October 2015 Location: Near Redmond, WA
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Senior Member Administrator |
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Regardless of what was up on Bob's site, if we have a v271 binary on the wiki, we technically need to have the v271 source available as well - since Jim K's code contributions are under the GPL which requires the source be offered with the binary.
I'll take it down later (only admins can delete things right now...)
My plan was to link to the resources on the STG site on the wiki for now until we have working boards at which point I'll make new RBC Edition Design and Source archives for the wiki with all the appropriate license info.
[Updated on: Tue, 12 April 2016 15:39] Report message to a moderator
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