Re: IBM 2.1G in 755 (was: Toshiba 2.1G in 755)

[Michael Redmond <redmond@engr.wisc.edu>]

At 11:37 AM 10/10/96 -0400, Tim Tyhurst wrote:
>> >the caddy connector to prevent the ThinkPad from erroneously
>> >jumpering the device to be a slave. Of course, this won't work
>> >if the drive is supposed to be a slave (presumably whenever the
>> >drive is in a docking station?) but it works for me right now, anyway.
...
>> If I read your message right, the caddy connections inside the notebook are
>> preset to jumper pins 48 to 50 on the drive because of some weirdness of
>> IBM's making (incompatible use of those pins from old drives to new drives).
>> You must have traced the caddy cable to find the correspondence between
>> drive pins 48 and 50 to the corresponding caddy pins (?? and ?? -- can you
>> tell us which pins these are?). Then you put tape on those caddy pins to
>> disable the "motherboard" jumper?
>
...
I had to see this to believe it...so I looked up the jumper config for an
older IBM 17mm drive (DHAA-2540 -- probably like the 540M I have in my
755CD). The web page for the jumpers on that is:

http://www.storage.ibm.com/techsup/hddtech/dhaa/dhaajum.htm

And compared it to the new IBM drives (DCRA-22160) at web page:

http://eagle.almaden.ibm.com/storage/techsup/hddtech/dcra/dcrajum.htm

It seems UNBELIEVABLE...but indeed the jumpering is EXACTLY
OPPOSITE...jumper in place from 47 to 48 to get MASTER on the DHAA, and in
place from 47 to 48 to get SLAVE on the DCRA. Talk about the total opposite
to compatibility...go figure!! Does IBM want to make sure we buy new systems
for their new drives or what? I must be missing something here.

Thanks
Mike Redmond