> > Are you sure the drive is ESDI? I think the model 70 shipped with an IDE
>> drive.
>
>The IBM PS/2 Hardware Interface TechRef contains a pinout of the hard
>disk connector. The signals look to be almost a subset of the MCA
>signals. It certainly doesn't look like an ESDI interface.
From what I've seen, including the data at 'IBM P70 Project',
the IBM DBA ESDI drives were only compatible with the models 55sx,
and 70 desktops, and the P70 portable. It shows the drives capacity
maxing out at 160MB. To quote Peter Wendt (those who read
comp.sys.ibm.ps2 will know the name) from this page:
"Don't forget that IDE was not very common in the late 80s
... and mostly ignored by IBM as "silly stuff" (what it is). They
developed a lot ESDI-based stuff and treated HDs as ESDIs - not only
because it is easier to use 64 heads / 64 sectors as basis and
re-calculate the (lower) number of cylinders rather than dealing with
odd sector / cylinder and head numbers. This is mostly done with the
adapters hardware already - and the BIOS is "ESDI focussed" - the
drives true geometry however totally differs in fact.
"But what. The generic term "IDE Intelligent Drive Electronic" is
used for most drives that have controller and harddisk mechanism in
one physical unit - in contrast to the "classical design" with
separate (unintelligent) harddisk and separate controller -
disregarded, which encoding / translation or writing method they
*technically* use. Therefore Carlyle is right in a way.
One *could* nontheless define it more accurate and set the borders a
bit tighter - and limiting the term "IDE" to the Conner / Seagate /
WD creation invented for "small inexpensive desktop harddrives",
which factically use an enhanced / expanded / watered ST-506
specification and RLL 2.7 or such stuff."
--
Home of the TRS-80 Model 2000 FAQ File
http://www.cchaven.com
http://www.geocities.com/siliconvalley/lakes/6757
Received on Thu Dec 20 2001 - 12:15:48 GMT