Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucbvax!agate!shelby!portia!roadman
From: roadman@portia.Stanford.EDU (arthur walker)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Accelerating an XT Bridgeboard. Possable?
Summary: accelerating 2088
Message-ID: <4455@portia.Stanford.EDU>
Date: 13 Aug 89 01:48:35 GMT
References: <196@stpl.UUCP>
Sender: arthur walker 
Organization: Stanford University
Lines: 37

In article <196@stpl.UUCP>, peterc@stpl.UUCP (Peter CAMILLERI) writes:
..
> Is it possible to use a PC style accelerator card to give his machine at
> least crawling pace speed? The card he is considering is the SOTA 286i,
> but we would welcome discussion on any experiences anyone would have to
> offer. 
I don't think the SOTA will work.  In general, those for which you must
remove the 8088 won't work, and that's almost all of them.  I have an
ORCHID turbo286e, which simpply plugs in on the bus, and it works. 

The 8088 boots while the 286e does its POST and waits.  A device driver is
loaded on the 8088 system and in AUTOEXEC.BAT, the user is given the
choice of whether to reboot to the 286.  If so, a TSR is loaded which
allows/commands the 8088 to handle i/o requests via its own bios routines
(from rom and PC.BOOT), which the 286 might not do as well.  Any memory
below the TSR and above the resident portion of MSDOS
is used as a disk ram cache for the 286.  

A 64k segment
is shared between the machines, and care must be taken in installation
to avoid collisions between it and the janus memory. 
The 286 is fed its dos, and it loads a driver which makes all its bios
calls get passed to the 8088.  Writes return immediately.  From the DOS
prompt one can move from one machine to the other; 286->88 means that
the disk cache gets flushed.

The installation program allows lots of tuning.

Applied Reasoning makes 286 and 386 cards that act likewise.  BTW, the
286 cards cost more new than a tradeup to a 2286 would, but you can
occasionally find them cheap enough for it to make sense, if you have
PC slots to spare.

> Peter

art walker
roadman@portia.stanford.edu