BSD UNIX minicomputer

Well, after a bit playing with retrobsd project I decided to build another useless machine. It was fairly simple - the whle device consists of three parts - main board, terminal and keyboard.

setup

Motherboard
I used main board I designed last year for retrobsd project. I didn't want to spend RAM and execution speed for keyboard and display drivers, that's why I connected terminal and keyboard to tty0 device. What more, I have no experience in writing UNIX drivers.
There is probably not much to be said about the mainboard - more info is at retrobsd project page.

Terminal
I took code from Matthew Sarnoff and adapted it to my device. It is rather messy, so you better don't look at the sources. The original bits from Matthew are the commented ones. My code is uncommented.
I used dsPIC33FJ128GP802 just because I had it on hand, no special reasons for using this MCU. Many of PIC24 devices should work too with small to no changes. I'll do it in future, as this dsPIC has higher current than I would accept.
LCD is RX240128A, resolution 240x128 gives 60x16 characters in 8x4 matrix. The terminal works at 115200 baud and currently there is no backlight manipulation, though there is transistor ready to do this.

Keyboard
That was quite easy - I wrote this simple code in PIC16 assembly (just because I wanted to do it in assembly) in one evening. It runs on PIC16F873A, but it should work on virtually any PIC16 in 28 pin package with USART. Debouncing is poor, it is subject of future improvement. There is nothing special about it - just keys matrix and PIC, I don't even have schematics of it. If you are capable of building this, you should be able to guess hardware connections from source files.
Keys come from old 8-bit czecho-slovak computer from 80's era, PMD-85. I had one piece in very bad condition, so after long resuscitation it served as organ donor for repairing other PMD's.

Whole device draws about 100-150mA, depending on tasks it executes. I'm planning to bring consumption few times lower to allow longer play-time on small Li-Ion cells.


Video at youtube
Link to picassa album
Package containing display sources, PCB artwork and keyboard sources
For more question, fell free to ask me via e-mail or so.



Updated 20.02.2013
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