root@cca.ucsf.edu (Computer Center) (09/20/88)
One item of extension to Minix which seems to me terribly obvious but I have not seen anything about is a ramdisk implementation based on expanded memory. There are a large number of PC's around with these memory expansion boards which seem the obvious answer to much of the memory crowding and temporary space difficulties that have been the object of complaints. As an example, I have an AST Premium board in an IBM PC with floppies which would allow for the equivalent of two 360K floppies worth of system residence and, with the piggyback expansion, a full megabyte of /tmp while leaving 640K for the active memory and two complete floppies for removable data etc. Such an program should make systems with only floppies as removable storage quite effective for many applications. Has anyone done such an implementation? Thos Sumner (thos@cca.ucsf.edu) BITNET: thos@ucsfcca (The I.G.) (...ucbvax!ucsfcgl!cca.ucsf!thos) OS|2 -- an Operating System for puppets. #include <disclaimer.std>
rwberry@hubcap.UUCP (Robert W Berry) (09/20/88)
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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