3 Dec
2007
3 Dec
'07
8:58 p.m.
Chuck Guzis wrote:
One other thing--there's a squib in the "New
Products" section of
January 1984 Microsystems about their System 1000 "multiuser
expansion".
But I wonder if an early 1984 box would be an 80286 unit.
Cheers,
Chuck
Micro5 initially made a system with an 8086 that ran basic around 1981
or so.
They developed a PC clone with their own BIOS that targeted the AT clone
market soon after the AT came out. They caused quite a stir by figuring
out that Microsoft's extended ram disk driver used what was called the
LOADALL after it was fessed up to by intel.
Initially intel had added such instructions to the dies and then enabled
them when they produced what were called bondout parts for their In
Circuit Emulators, or ICE products. when they came out with the 286 and
built their ICE they didn't disable it on the production parts.
The significance of LOADALL was that it offered a way to load not only
the registers that one normally could modify with architectural
instructions, but it could also modify others, some of which happened to
be the registers that were computed and were the actual memory pointer
registers for certain memory operations.
The 286 also did not have the capability in the architecture to address
memory over 1mb once in "protected" mode and once in protected mode one
had to reset the cpu to get back to real mode (the mode that dos runs is
is real).
IBM's drivers were very slow because they had to actually reset the 286
after any memory operation the extended memory, since to do it by normal
instructions one had to enter protected mode. So they would reset after
each operation, and run very slow.
Microsoft had produced their extended memory driver, and advertised that
ran very fast, and it turned out they were able to do the extended
memory operations with only the penalty of using LOADALL to get to the
memory.
long story, short Micro 5 also came out with a driver after noticing
that there was no reset when they ran the ibm driver and there was with
the microsoft one. Their bios blew up on the microsoft memory driver
because of some assumptions related to the reset the IBM driver had to do.
They supported more slots and memory that other systems (I think they
came out with > 32mb later) and eventually signed some contracts with
Novell to supply large servers.
After Samsung bought Micro5 out, the remaining business other than the
server business was spun off due to the fact that it ran larger numbers
of slots than most clones.
Jim