Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!seismo!ll-xn!ames!oliveb!spud
From: spud@oliveb.UUCP (John Purser)
Newsgroups: comp.sys.att
Subject: Re: I finally solve one of my own problems (maybe)
Message-ID: <2264@oliveb.UUCP>
Date: Fri, 24-Jul-87 11:10:50 EDT
Article-I.D.: oliveb.2264
Posted: Fri Jul 24 11:10:50 1987
Date-Received: Sat, 25-Jul-87 14:52:47 EDT
References: <3838@pyr.gatech.EDU>
Reply-To: spud@oliven.UUCP (John Purser)
Organization: Olivetti ATC; Cupertino, Ca
Lines: 38

In article <3838@pyr.gatech.EDU> jkg@pyr.UUCP (Jim Greenlee) writes:
>
>Apparently there is a jumper (labeled W3) on the Western Digital controllers
>that enables/disables the ROM on the controller card. On my disk controller
>this jumper is missing (the solder pads on the PC board are connected by a 
>trace, which causes the controller ROM to be enabled). 
>
>It appears that all I have to do to enable the ROM routines on the mother-
>board is cut this trace, install shorting blocks for the appropriate drive
>type, and set the DIP switch on the motherboard (switch 3 in bank 1) to 
>select internal BIOS code for the hard disk.
>
>						Jim Greenlee
>
Is the ROM on the WD board socketed or soldered? If it's socketed I would
just pull it out of the socket rather than cut the trace. The power on
routine of the BIOS won't find the WD ROM if its been pulled from the socket
so by default it will use the motherboard ROM BIOS.

At power on time the BIOS startup routine looks through segments C000,
D000, and E000, for valid option ROMS. The details of the address space
that is searched and what makes up a valid option ROM are in your tech. ref.
somewhere. When a valid option ROM is located it is called from the
motherboard BIOS. The option ROM can then do any inititialization neccesary
and retrun to the motherboard BIOS. In the case of your WD controler the
initialization code will re-vector int 13h to the WD BIOS on the controler
board. So by removing the WD BIOS you've solved your problem.

If the WD BIOS is soldered then see if you can't find a schematic for the
controller. I think you would find that the trace you have
suggested cutting goes to the chip select line of the WD BIOS. I'm not an
EE and I don't have a good understanding of schematics and board layout
but I think that cutting the trace would also work. Pulling the WD BIOS
is more easily reversable though.

Good Luck, Have fun.

John Purser