BSI 486/25 crashes with AD1542B at 8MHz

[Michael Squires]

I posted a note some time ago about using a BSI 486/25 as a portable
UNIX 386 box.  The only limitation I've run into so far is that
the Adaptec 1542B controller runs fine with a max 8MB DMA transfer
rate under UNIX but crashes systematically under DOS.  It runs OK
at 5MB and the next speed up.

The disk subsystem (1542B + Micropolis 345MB SCSI) is a little slow.
A 386/20/cache/Miniscribe 660MB ESDI/WD1007V uncompresses a 750K file
in 40.5 secs (21.3 user, 5.5 sys) while the 486/25 does the same file
in 1:10 (27.4 user, 5.5 sys). This is with DMA at 8MB/sec.

As I run DOS usually from ODT-DOS (DOS Merge 386) this is so far not
a problem but it suggests that the motherboard is not the best.  If one
is building a new one you might look at the MicroWay 486 motherboard, which
should fit.

The 3C503 does not seem to work properly (generates spurious entry
for Arnet serial card) and crashes TCP/IP regularly; the WD8003E
works fine (set at IRQ 2, I/O 380, mem at D0000).

-- 

Mike Squires (mikes at iuvax.cs.indiana.edu)     812 855 3974 (w) 812 333 6564 (h)
mikes at iuvax.cs.indiana.edu          546 N Park Ridge Rd., Bloomington, IN 47408
Under construction: mikes at sir-alan@cica.indiana.edu