3b2 disk limit

[Dennis S. Breckenridge]

paul at voicebox.dialogic.com (The Imaginative Moron aka Joey Pheromone) writes:

>However, I have heard that some early /300's (with flat pack processor
>chips,which mine has) had problems addressing large disks, because of
>a disk controller bug. My informant was vague about the numbers, but
>he said 30mb would work, but > 50 mb wouldn't.

Some of the very early 3B2/300 cpu's had a problem with DMA channel
assignemnt and could not support a hard disk larger than 30 megs. 
If you are running a 72 meg (CDC WREN-II) then the fix is not in. 
It's a simple mod to the card, I cannot remember what it is. If you
call Richard Meesters (AT&T) at (416) 479-0174, he can put you in touch
with someone that used to modify these old boards. I recall that it
was just the addition of a jumper and a couple of cut traces to fix it.
Rich has been very helpful in the 3B2 area in the past. 
Once you have the mod in, then the 3B2/300 will support 2 * 72 megs. 
I have not tried anything like (boo hiss yuck :-) *Maxtor* drives but
I am sure that woods at robohack could expand on what is required there.
The standard drive is the CDC WREN-II, but you can drop in pretty 
much any drive that meets the CDC spec (Hitachi, Micropolis, Fujistsu)
You also mentioned devtools. The new and improved version of this
is called idtools. You may want to track a copy of it down.
-- 
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Dennis S. Breckenridge  (604) 277-7413   dennis at nebulus.uucp           VE7TCP
               Still brain dead after all these years :-)     
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