Hello Folks,

I've run into a blank wall with my attempts to up grade an old 486 SX
system.  I want to put a somewhat larger hard drive and CD-ROM into it, and
I thought that using a Promise EIDE MAX II upgrade and controller card would
do the trick.  It seems like this should work, but it hasn't.

The mother board is of unknown make.  When it boots up it shows that it is
using an American Megatrends BIOS, and it says " OPTI-496 Rev.B 15/7/92".
At the bottom of the screen, it has this
"30-0100-DG1112-00001111-070791-OP3DX/PI-F".   (It might be an Aquarius
Systems or ASI motherboard, but they are no longer in the motherboard
business, so I couldn't find any information about these motherboards on the
web, assuming it is an ASI MB.)

The main chips on the board are marked OPTI 82C496 and Samsung KS83C206C.
The processor is an Intel 486 SX 25mhz.  I'm trying to install a Quantum
BigFoot 2.1gb and a CD-ROM 32x.  There is no hard drive connector built into
the motherboard, rather it has an ISA board on which are one Hard Drive
Connector and one Floppy drive connector.  Two devices can be attached to
each of these connectors, as the BIOS has entries for Hard Disk one and two
and Floppy A and B.

When I install the EIDE MAX II board, the system cannot access the hard
drive.  I've followed the recommended instruction to attach the hard drive
to the original controller connection, set the CMOS to no hard drive
installed, and disabled PnP in the EIDE MAX II BIOS.  I've attached the
CD-ROM to the Promise card as a only drive on that connection and set it to
master.  The Quantum is the only drive on the cable going to the original
controller card, and it is also set to master.  I've double checked that I
have the pin #1 hooked up to the striped side of the connector.  I've made
sure that the CD-ROM is on the first IDE port on the Promise card, and I've
tried all the standard settings for this port on the Promise card (primary,
secondary, tertiary, quaternary).

I can get as far as the Promise BIOS recognizing and identifying the two
drives correctly on the screen during the boot process.  It says that it has
loaded its BIOS successfully, but the hard drive remains inaccessible.  If I
disable the Promise card, I can access the hard drive, though the original
BIOS, but only about 500mb of this 2GB hard drive.

I was able to install the EIDE MAX II card, this hard drive, and CD-ROM into
another, somewhat newer 486 DX2-66 system successfully, so I'm fairly
confident that the parts that I am using are all in working order.  But,
after trying every combination of settings and hook up arrangements that I
could think of, I've come to the conclusion that there must be some
compatibility issue between the EIDE MAX II and the BIOS in the 486 SX
system.

If anyone can think of some steps to take in order to track down where the
incompatibility or conflict is, I'd be happy to give them a try.

As a side question, this motherboard has an unusual ISA slot on the far end
at the edge of the board (left side looking at the board from the front).
It looks very similiar to the other other 16 bit ISA slots, and in fact an
ISA card will work in this slot, but this slot is slightly different than
the others.  It seems to be marked on the motherboard as "Local Bus Slot",
and it looks like there may be another set of contacts down further in the
slot, so they don't show looking at it from the outside.  Does this kind of
slot sound familiar to anyone?  Any idea what this kind of connection was?

TIA,

John

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