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DOS 2.1 On Cartridge?

PostPosted: Wed Mar 08, 2017 8:42 am
by Tempest
Has anyone seen this before? It's DOS 2.1 on a PCjr cartridge.

http://atariage.com/forums/topic/263021-ibm-4860-pc-jr/#entry3712917

Re: DOS 2.1 On Cartridge?

PostPosted: Wed Mar 08, 2017 10:46 am
by Trixter
Wow, never seen that before. Makes sense to have though, you'd never need a boot floppy.

Re: DOS 2.1 On Cartridge?

PostPosted: Wed Mar 08, 2017 11:35 am
by Vorticon
Can this cart be replicated? Could a later version of DOS work as well in that format?

--Walid

Re: DOS 2.1 On Cartridge?

PostPosted: Wed Mar 08, 2017 4:07 pm
by usotsuki
DOS 3.00's boot files (ibmbio.com, ibmdos.com, command.com) are about 59K. Between the overhead of a filesystem and an INT13 driver, I'm not sure you could fit even that in 64K - you'd need bankswitching hardware.

Re: DOS 2.1 On Cartridge?

PostPosted: Wed Mar 08, 2017 5:54 pm
by Trixter
It is possible if DOS doesn't need to RUN out of the cartridge; you could store it compressed, then decompress it into ram as if you were loading it from disk. However, running off the cartridge is the real benefit, because that frees up more memory to run programs (something important for a system that steals from system memory for its video buffers).

Re: DOS 2.1 On Cartridge?

PostPosted: Thu Mar 09, 2017 12:55 pm
by Tempest
He posted pictures of the chips. They're regular ROMs, not EPROMs like I was expecting. This just gets stranger and stranger.

Re: DOS 2.1 On Cartridge?

PostPosted: Thu Mar 09, 2017 5:09 pm
by alanh
Tempest wrote:He posted pictures of the chips. They're regular ROMs, not EPROMs like I was expecting. This just gets stranger and stranger.


Why is that strange? I wouldn't expect to UV erase them in the field.

Re: DOS 2.1 On Cartridge?

PostPosted: Fri Mar 10, 2017 7:47 am
by Tempest
I mean I thought this was a prototype of sorts. A one off that maybe the internal IBM people used or something. I didn't think this was actually a production cart.

Re: DOS 2.1 On Cartridge?

PostPosted: Tue Mar 21, 2017 7:31 pm
by Meknapp
It would be awesome to get a dump of this cart!

Re: DOS 2.1 On Cartridge?

PostPosted: Thu Mar 23, 2017 8:41 pm
by OldComputerGuy
How big is the cartridge space in memory?