The CP/M based $30 OLPC computer??

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The CP/M based $30 OLPC computer??

Postby eniac42 » Wed Nov 14, 2007 11:32 pm

I posted this on SlashDot, I dont know if it will make it to the front page.. Thought you might like to see it..
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Recently I have been looking at the hardware of certain MP3 players - the so called "S1MP3" players.

These little mp3 players are neat devices - they are based around a Z80-compatible ATJ2085 processor - <URL:http://www.s1mp3.org/files/datasheets/ATJ2085/ATJ2085_datasheet_v1.5.pdf>

They are clocked at up to 50 mhz, and can address from 128MB up to 2 Gigabytes of banked RAM, address a small LCD display (some of the MP4 players have 320x200 OLCD screens), a software controlled USB bus interface, a DSP stereo audio output, and so on..

Instead of re-inventing everything with the proposed "Swan" API, which sounds like it is not progressing fast, (no criticism - I have been there..) why not just hack and implement CP/M (maybe +GSX) on these devices? This was the Operating System that used to run on 8080/Z80 CPU's back in the old days - later it became CP/M 86, then DR-DOS, then (currently) OpenDos. There are thousands of Shareware/Freeware/Open source programs for CP/M, and the OS itself is now open software. Being over 20 years old, there are no software patent issues to worry about.

CP/M 2.2 used to run in a few Kilobytes RAM, and it could take care of accessing the basic peripherals - emulated ASCII terminal, FAT (FlashRAM) drives and so on.. Just implement the extra SWAN API features needed as "unimplemented" (in CP/M) INT/CALL routines.

Other observations - a USB keyboard could be connected via the USB port, with some clever hacking to make the USB bus interface act as a master USB device server, operational under CP/M. Or, a spare 5v input line could serve to read a standard (cheap) PC Keyboard serial interface line. If input is via external keyboard, there would be spare output lines - for instance a simple UHF modulator could be driven directly - heck, with a bit of 74xx logic and a UHF modulator (AKA ZX81/Spectrum).

In short, could these very-common-devices serve as a sort of uber-cheap OLPC-style project for the rest-of-the world? And would there be any old Z80 coders out there prepared to work on it?
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Re: The CP/M based $30 OLPC computer??

Postby wladston » Sun Dec 02, 2007 10:40 pm

wow - that is a really interesting idea!!

I would really like you to come talk with us on the mailing list - lists.s1mp3.org, the s1mp3-dev list. Maybe we can come up with some interesting way to implement what you are saying. would not fit the laptop per child thing, but surelly, a very powerfull $30 or even $20 computer can be obtained out of it, I'm sure ...

I'm waiting for your post there ;)
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1GB "mp4" s1mp3 player. Not remarked.
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Re: The CP/M based $30 OLPC computer??

Postby ian_hawdon » Mon Jan 28, 2008 6:51 pm

Yeah, this sounds really interesting... more info please?

I haven't seen this appear in the mailing list yet, it sounds crazy enough to work :D
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