RE: Pet 8088 coprocessor board for sale on Ebay

From: Hoffmann-Vetter, Martin <martinhv_at_arcor.de>
Date: Wed, 19 Jan 2011 05:18:40 +0100
Message-ID: <000201cbb78f$f41c41d0$1b09a8c0@mhvnb10>
Hello,

> MSDOS.PRG is only the 6509 loader. I
> tried to disassemble it, only got into first few bytes so far. I see
> that it loads the 8088 code directly from disk sectors and puts into
> RAM, then launches the 8088.

Yes, it loads 54 sectors starting at Track 1 Sector 21 to memory bank 1 address 0. After reading sector 22 the next sector is sector 0 on the next track. So it loads IO.SYS at 10000 (6509) or 0000:0000 (8088) and MSDOS.SYS at 11800 (6509) or 0180:0000 (8088).

> Then it contains lots of other stuff I had no time to disassemble,
> probably all the IPC interface on the 6509 side.

This stuff must do all the redirection of io access (keyboard, monitor and disc, ...).

Greetings

Martin


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