🚀 go-pugleaf

In <TyDswB1w164w@cellar.org> robinson@cellar.org (Alan Robinson) writes:

>> [Questions regarding using 8 bit disk controller in 16 bit machine ]

>You might try setting your drive type in CMOS to NONE. I was able
>to use Western Digital 8 bit controller with an ST-251 in my 386
>by doing that. I am not sure why it works but my guess is that if the
>BIOS does not see a Hard Disk in it's CMOS table it looks for an XT
>controller (at segment C800) before assuming that the system only has
>floppies.
>   While the XT controller can be made to work, performance is less
>than spectacular. In fact I found that while the optimum interleave
>for that drive/controller combination was 3:1 in an XT, I had to
>increase it to 5:1 in the 386. Perhaps someone on the net can explain
>that. You can get 16 bit 1:1 controllers for 45 or 50 dollars and the
>increase in performance is incredible. That might be the best thing
>to do.
>   One other thing: If the drive has been used with another type of
>controller, you might have to do a low level format to get things
>going.

I too am trying to help a friend get a XT controller working on
an AT.  and we too found that setting drive types to none, made
the drive boot.  Its still kind of odd, because it won't boot
thru to floppy if there is one in the drive, and you can't
do a control-c to stop AUTOEXEC.BAT.  

But regarding the interleave, I think the problem may be that
the XT card has an 8 bit ROM BIOS, while the AT cards have a 16
bit wide one.  Anycase, doing two fetches to get a word would slow
down the AT.  In my researches, I found a program in the archives
(garbo I think it was) called RAMIT66.ZIP.  what this did was copy
the ROM BIOS to RAM, making certain translations.  This lets the AT
run at full speed and this may let you get back up to 3:1 interleave
or better.

I saw a reference by someone to DISABLING the cards BIOS completely
to let the 8 bit card do its stuff.  Is it possible that AT's contain
the code to drive disk controllers without BIOSes, and using the
BIOS just screws things up.  A jumper was mentioned to disable
the BIOS.  Anyone know what the story is on this?
A
A







>------
>robinson@cellar.org (Alan Robinson)
>The Cellar BBS - (215) 539-3043