Re: 486 problem



"Michael A. Terrell" wrote:

Meat Plow wrote:

On Wed, 07 Feb 2007 15:25:18 +0000, Michael A. Terrell Has Frothed:

"captainvideo462002@xxxxxxxxx" wrote:

I just installed a 486 board that someone gave me to replace a failed
386 into an old machine. There are programs on this machine that we
still use. The 486 board has Phoenix bios. Initially the setup option,
(F2) came up during post and allowed me to get into the bios to set
the drives up and the date. I did that and exited saving the
information. My 386 machine used an MFM controller board and I
plugged it into the new 486. The 486 however has an on board IDE
controller which it now occurs eto me perhaps should have been
disabled. So now when I try to boot it counts the ram and displays a
cache message but I get this message that reads : "last boot failed,
use default configuration". I assume that the default configuration is
part of bios but the problem is that the F2 option on startup is now
gone and I can't seem to get back into bios. I tried disconnecting the
battery and shorting across the ternminals on the board, and even
pulling the bios chip and shorting all the pins on a pad of aluminum
foil thinking that this may dump the memory, but nothing will get me
back. Does anyone know of a way to get back into bios after the
option no longer presents itself. Thanks very much for any assistance,
Lenny Stein, Barlen Electronics.


Lenny, most of the 486 motherboards I've worked with were too fast to
support the MFM drive controllers. Some 386 boards were flaky, or
didn't work at all when they were new. The 16 bit MFM controllers were
made for 286 computers, and IDE was introduced before the 386 became
popular.

IIRC you are correct. BTW MFM is stil the recording method for floppies.

It was the most popular method, but there were a few other floppy
data formats over the years.

As a side note, IDE drives are RLL format

Run length limited compression. I recall when the 32 MB HDs came out. That was
the first HD I bought on an AT expansion card in fact. Probably the first 3 1/2"
drives too. They were actually 20MB MFM drives with an RLL controller. The MFM
is just modified frequency modulation IIRC - unrelated to the RLL, so they were
MFM RLL drives.


, with a built in controller. The IDE port is a simple interface to connect
the
controller to the computer's various busses.

The physical IDE connection wasn't much more than an AT bus expansion connector
in the early days AIUI.

Graham

.

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