32-bit disk access on 755

[george@cs.nps.navy.mil (Robert George)]

>> The problem I'm frustrated with, is that according to the 75x FAQ, 32-bit
>> disk acesses should work on the ThinkPad with WFW 3.11.  However, when
>> I turn on 32-bit disk acesses in the 386 enhanced menu, I get the following
>> error when Windows reboots:
> 
>> The Microsoft Windows 32-bit driver (WDCTRL)
>> validation failed at phase 07, 1F
> 
>> To continue starting Windows without using the 32-bit
>> disk driver, press any key 
> 
>> Has anyone successfully used 32-bit disk acess on the 755's?   Is it
possible
>> that I new a BIOS update? (I have 1.07).  Is it possible that something
>> that Sigma Data is doing is incompatible with 32-bit disk acesses?
> 
>> Thanks,
>> 
>> Robert George
>> (george@cs.nps.navy.mil)

> The IDE spec only allows drives < 512MB. The ThinkPad BIOS adds support 
> for > 512MB, which allows the drive to be accessed. However, 32-bot disk 
> access circumvents the BIOS, therefore Windows can;t understand your drive.
> 
> CONCLUSION: You can't use 32-bit disk access on ThinkPads with > 512MB 
> drives.
> 
> --
> Adam Lee Wilkinson          * Just remember, no matter where you go,
> adam@tiamat.umd.umich.edu   * there you are!   
> Compuserve: 75470,71        *                 - Buckaroo Bonzai
> 

Well, not exactly.  The enhanced IDE BIOS is called a "translation BIOS."
I beleive that what is happening is that the BIOS intercepts disk requests,
expands it from 7-bit addressing (512M) to whatever the upper limit of
EIDE (does anyone know what this limit is?), and passes it to the disk 
controller.

Western Digital _does_ have support for 32-bit disk access for some hard
drives.  There is a FASTDISK driver available from WD, but it is intended
to provide 32-bit disk access in Windows 3.1, not WFW 3.11.  I couldn't get
it to work on the ThinkPad, but there's still some hacking left to do.

Peter Bernota (peter.bernota@execnet.com) was kind enough to inform me of
a new WFW 3.11 driver (wdctlr) from 8/22/94.  This is another good
possibility.

>From the benchmarks I have seen, the 32-bit disk access really is worth all
this effort.  With 32-bit disk and file access, WFW caches disks 3 times
faster that Smartdrive, which was in turn faster than all the other 3rd
party cache programs.


Robert George
(george@cs.nps.navy.mil)