A 486 gives invalid drive specifica

[anothersmiley]

A 486 gives invalid drive specification when trying to access the hard drive. The drive and controller were tried in a different computer and worked fine. A drive and controller from a different computer were tried in the 486 and the error message came up. The bios autodetects and sets the drive properly in cmos.

The drive is a Fujitsu mpd3064at . When running ontrack the drive is identified as a Gukiusu mpe3165au
Basically every other byte is incremented by 1 when being read.

Ontrack reports that reads from the mbr are being redirected to another sector.

I have tried fdisk. It tells me the disk has been partitioned, but when I reboot and run fdisk again there are no partitions on the disk.


Any idea of how to get the computer to access the hard drive would be greatly appreciated.

 

[edfair]

Until MBR is right , the drive is a paperweight. Time for a lowlevel format. Should match drive timings to controller timings. Ed Fair
efair@atlnet.com

Any advice I give is my best judgement based on my interpretation of the facts you supply.

Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[anothersmiley]

Negative on the low level format. I installed the drive on the pentium and had it working. I read the boot sector using debug. I then installed the drive on the 486 and again read the boot sector using debug. It turns out that every other byte always has the least significant bit set. I then wrote 00 to a full sector (not the boot sector)of the drive using debug on the 486. When I read the sector back on the pentium it read it back as 01. It appears that bit 8 on the data bus is stuck high. If this is the case why do I not have trouble with the video adapter?
I am looking for a utility that will let me put the bus in a known state so that I can check if the cpu is toast or if a bus driver is shot. Again thanks for any help.

 

[edfair]

Not on the data bus, on the output of the controller chip. On every other character? Not likely. So you have a controller that is writing stuff that another controller can't read. Both ways. Symptom of timing problems? Probably. Solution? Reset the timing. Probably won't be readable by the pentium, but you could be surprised. Ed Fair
efair@atlnet.com

Any advice I give is my best judgement based on my interpretation of the facts you supply.

Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[edfair]

After reflection: First is to put the drive on the secondary controller and see if it IDs there.
Next is to replace the data cable.
Haven't been into the interface specs recently, but suspect that it is a 0 volt active signal and an open would be a hot signal. Ed Fair
efair@atlnet.com

Any advice I give is my best judgement based on my interpretation of the facts you supply.

Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[anothersmiley]

The drive is fine. It turns out 1 of 2 ls245 octal bus transceivers on the motherboard has 1 bit that is always high. Will either have to replace the chip or scrap the board.