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Date:      Sun, 10 Sep 1995 19:28:54 -0600
From: (David Kelly)
Subject:   PC BIOS Setup Questions
Message-ID:  <v01530501ac7935ab1a4a@[]>

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Recently added an Adaptec 1542CF to a previously reliable 486DX33 running
2.0.5R. You may remember me as the one this past week who did "make world"
to get "2.1.0-STABLE" while still multi-user. That seemed to work fine but
I started getting spurious resets when running long (hours) CPU intensive
tasks. Rebooted "kernel -s" into single user, used fsck to clean everything
up, "mount -a" to get my filesystems back, and did a new "make world", a
new kernel, etc. Same problem as before. MTBF is 4 hours of active use.

The AHA1542CF would not work with an ISA bus speed of 8.0 MHz, seemed to
work at 5.6 MHz, so I set it to 5.0, all this before the above problems.
See below, BIOS bus speed on this machine is set to 7.15 MHz.

I no longer suspect FreeBSD, as all this happened shortly after adding the
AHA1542CF and is very similar to problems seen on my other 486DX33 with an
UltraStor 14F (2.01 BIOS with adjustable bus occupancy times). In both
cases I have a swap partition on a small SCSI drive and am crunching data
on an IDE drive where FreeBSD is.

The machine with the UHA14F has a Symphony chipset and does not reset on
exit from FreeBSD installation. When it dies running the console suggests
there has been a memory parity error, once it reset in the middle of the
night, once it said it was going to reset in 15 seconds but never did, and
another time it just froze at "syncing disks". The other 486 has an ETEQ
(?) chipset and properly resets out of intallation and reboots after
whatever the problem is. Don't know if any message is on the console as I
learn of the problem when I hear "Bong, scrunch scrunch" after the fact.

Both 486DX33's have AMI BIOS, ISA only (no VL-bus). There are some
parameters in the BIOS setup that I'd like some advice on:

What is "Decoupled Refresh Option" which is currently enabled?

What is "Extended ALE" which is currently enabled?

What is "I/O Recovery Time (SYSCLK)" which is currently "0"?

What is "Bus Clock Selection" which is currently "CLK2/3" but defaults to
"CLK2/4"? With options such as "ATCLK", "7.15 MHz", "CLK2/5", etc. The
Symphony chipset machine reports disk errors booting the 2.0.5R boot disk
if CLK2/4 is used but works fine with CLK2/3 (which is why it got set

Back in 386BSD 0.0 days it was recomended that any BIOS ROM or video
shadowing be disabled. Is this still true? (Mine is disabled).

Is it time to unload these MB's on some poor unsuspecting DOS user and buy
something documented? Is this what is meant by "does not support bus master

David Kelly N4HHE,,
The human mind ordinarily operates at only ten percent of its
capacity -- the rest is overhead for the operating system.

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