2011-05-09

SBC6120 - Project Done!

It is done! My SBC6120 finally has a case that I am proud of. It still needs some finishing touches (namely some light pipes for the LEDS on the board to the front panel), but that's about it.


Since I haven't used it for quite some time I forgot some of the "intricate" details of working with it:
- I lost an incredible amount of time in a hardware bug that did not exist, simply because I forgot that the communication interface is 9600-7E1 and NO handshakes (hardware or XON-XOFF)... Minicom in linux installs default with hardware handshake, you see the boot message but you cannot write anything...
- and OS/8 only works with CAPITALS... (This is not a MAC OS8!, Mac friends look elsewhere).
To fit everything inside the Hammond box, I built a base in 1.5mm plastic and glued nylon screws upside down, these would fix the SBC on the lower part of the case, I've built a power supply board to convert 12V in the 5V needed for the SBC, finally I designed custom front and back panels.
I've built four prototypes of the front panel (in paper) and glued them to 2mm thick foam to get a look and feel of the panels before committing to fabrication. I used the services of Schaeffer AG for milling the front and rear panel, their (freely distributed) CAD program is actually very nice and it is available for linux! (I had some problems with sending the design but the drawing was actually all done in linux). It isn't cheap, but sure is top-quality.


The reset button does not protrude to the external of the box as intended, but having a "insert pencil here to reset" hole is not so bad (might even be a feature :-). Here you can also see why there's a need for a light pipe.



The slots in the back are enough for cooling the SBC6120 and the 3.5'' IDE drive, it takes about six hours to serially download two disk images, the boards and case never exceeded ambient temp by more than 20C.


The whole case is quite small (for a PDP-8), here's a top view, a fair view of what's inside is in an older post and here. The paper sheet below is A4 size.


The final photo just like in Sparetimegizmos is my the SBC6120 with an HP-16C side-by-side, just like the "inspirational photo" from their site. Yes, the calculator is more expensive than the computer :-).


Next... Install some adventure games... like this one... :-)
what's the use of a computer other than entertainment....

4 comments:

Como se Resolve said...

Looks Good!

mjd said...

João! Your first post about the SBC6120 project was on 2011-05-07, and this post was on 2011-05-09, making it two years and two days from start to finish.

Congratulations! I always love to read your blog. Only one small problem: desperately need more articles! :-)

Mitch.

J Silva said...

Thanks Mitch,
I'm doing my best to keep up the posting. I'm a bit methodical so I try to do little steps before commiting to a big project all at once. So first I tried PCBs, then toner transfer, then the front panels and only then could I finish this project.
Thanks for the motivation, I'll try to post a few more projects..
Regards

mjd said...

I recently wrote about making PCBs at home:

http://capnstech.blogspot.com/