Subject: Re: AMD or Intel 80387 Math Coprocessor IC

From: "Eric J. Korpela" <[email-masked]>
Date: Thu Mar 6 20:11:55 2003

> > I don't currently have a DRX2, but I do have a DRX, which is essentially
> the
> > same thing without the clock doubled core.  The L1 cache made it about 20%
> > faster than an equivalently clocked 386.  You had to explicitly turn on
> the
> > cache, and set regions as uncachable.  (Caching the video card usually
> made
> > for problems.)
> 
> Guess I want the DRX2 then.  No sense in spending all that time on something
> just to have it be less than optimal.  I'll have to dig up reference sheets
> on 'em.
> 
> BTW, what do you run on the DRX?  I'm upgrading an IBM P70 luggable, the
> target OSes are AIX-PS/2 and Solaris in particular, and then as many others
> as will work.

Sorry for the delayed response.  I've used Linux, OS/2 Warp and Win3.1 on them.
Right now it's an OpenDOS machine.

Turning on internal cache requires ring 0 access.  OS/2 required a device driver at 
startup.  Win 3.1 and DOS run a program from autoexec.bat.   ISTR that the linux
kernel had support built in for the DRX.  I don't know about AIX and Solaris.

There are also later model BIOS versions that turn on the cache at boot.  I
don't know if the P70 would have that l turn on the cache at boot.  I don't
know if a P70 would have an appropriate BIOS.

Eric

---

From: "Robert F. Schaefer" <[email-masked]>
Date: Thu Mar 6 22:20:54 2003

----- Original Message -----
From: "Eric J. Korpela" <[email-masked]>
To: <[email-masked]>
Sent: Thursday, March 06, 2003 9:07 PM
Subject: Re: AMD or Intel 80387 Math Coprocessor IC

> Right now it's an OpenDOS machine.

Ok.  I was mainly looking to see if it was only kind-of compatable, but it
sounds like any quirks are minor or non-intrusive.

> kernel had support built in for the DRX.  I don't know about AIX and
Solaris.

Probably need a kernel patch to tweak the bits, same as linux.  I wonder if
NetBSD supports the cache...

> know if a P70 would have an appropriate BIOS.

Probably not, but if my googling has been any indication, there are a goodly
number of drx/drx2 chips installed in P70s-- it's about the fastest chip you
can install without major hardware voodoo or adding a CPU card.

> Eric

Bob