Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ames!nrl-cmf!mailrus!uflorida!gatech!hubcap!rwberry
From: rwberry@hubcap.UUCP (Robert W Berry)
Newsgroups: comp.os.minix
Subject: Re: Minix EMS Ramdisk
Summary: EMS implementation problems
Message-ID: <3004@hubcap.UUCP>
Date: 20 Sep 88 03:13:18 GMT
References: <1365@ucsfcca.ucsf.edu>
Organization: Clemson University, Clemson, SC
Lines: 28


     One nasty side of implementing a EMS RAMDISK (or more CORE MEMORY with
the EMS 4.0 spec) is that there are about 75 different makes of EMS expansion
cards on the market.  And while they all provide the same EMS interface to
DOS, the way the LIM standard is implemented differs slightly from card to 
card.
     Like you, I have an AST card, and with the EEMS hardware on this card,
it's perfect to swap procs in and out of the address space.  Unfortunately,
the people at AST have been a little less than helpful in letting me know
how their (my) card works.  Alas, without knowing how the card works below the
level of the device driver, it's going to be difficult to write an EMS (EEMS??)
driver for MINIX.
     A while back people got a EMS ramdisk going on AT-class machines, but only
with the help of the AT ROM BIOS, which had an interrupt service perfectly 
suited to copying blocks of text in and out of EMS.  No such luck on the 
PC cards.
     There is a glimmer of hope, however.  Some clone manufacturers (sp?) are
now putting LIM 4.0 hardware on their motherboards.  This may still not be a
standard, but it least it's a little easier to get info on.
     If anyone out there knows more about this, PLEASE JOIN IN.  Particularly
about the AST cards, I could probably come up with a driver, if only I knew
how to program the doggone things.
     Bob

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