DOS 2.1 On Cartridge?

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DOS 2.1 On Cartridge?

Postby Tempest » Wed Mar 08, 2017 8:42 am

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
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Re: DOS 2.1 On Cartridge?

Postby Trixter » Wed Mar 08, 2017 10:46 am

Wow, never seen that before. Makes sense to have though, you'd never need a boot floppy.
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Re: DOS 2.1 On Cartridge?

Postby Vorticon » Wed Mar 08, 2017 11:35 am

Can this cart be replicated? Could a later version of DOS work as well in that format?

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Re: DOS 2.1 On Cartridge?

Postby usotsuki » Wed Mar 08, 2017 4:07 pm

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.
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Re: DOS 2.1 On Cartridge?

Postby Trixter » Wed Mar 08, 2017 5:54 pm

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).
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Re: DOS 2.1 On Cartridge?

Postby Tempest » Thu Mar 09, 2017 12:55 pm

He posted pictures of the chips. They're regular ROMs, not EPROMs like I was expecting. This just gets stranger and stranger.
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Re: DOS 2.1 On Cartridge?

Postby alanh » Thu Mar 09, 2017 5:09 pm

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.
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Re: DOS 2.1 On Cartridge?

Postby Tempest » Fri Mar 10, 2017 7:47 am

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.
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Re: DOS 2.1 On Cartridge?

Postby Meknapp » Tue Mar 21, 2017 7:31 pm

It would be awesome to get a dump of this cart!
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Re: DOS 2.1 On Cartridge?

Postby OldComputerGuy » Thu Mar 23, 2017 8:41 pm

How big is the cartridge space in memory?
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