🚀 go-pugleaf

I wrote:
>I have a couple of CDC BR3B5 disks I want to talk SASI to. 
>[...]
>which controller chip I should go for?
>The discs complicate the matter by having
>19 heads and a bit rate of 6.5 MHz. They want MFM coded data.

Maybe I was a bit unspecific since I only got one reply (hi Doug! --
uunet doesn't like ames@uucp so no reply from me).

Well, the disks don't have a controller but I have full documentation.
They're not SMD, but maybe some predecessor. Anyway, I only have
Western Digital's Databook and cannot find a suitable controller.
WD1010 or 2010 are out, it would be too much problem interfacing them.
(The disks don't want no "stepping pulse" for one. They want the
cylinder address on a control bus. And the bit rate is too high.)

Maybe the WD1050 SMD-controller would work. Of course, it wants a
bit rate of 9.677 Mbits/sec and uses NRZ coded data, not MFM.
There may be more differences. I don't know how serious they are.
I can't seem to find any reference on the feasibility of converting
NRZ <=> MFM right now, would it be easy?
At least it's got a control bus for communication with the disk.

Then I've got to have a host interface. I have no possibility of
writing a new device driver, alas, so I must use what's available.
What's available is SASI. :-(

I would much rather like SCSI, maybe I can build a dedicated
processor to take SASI packets, converting and feeding them to
an SCSI bus controller? Seems a bit overkill though...

Anyway, please answer the following:

1. Do you know of any disk controller chip meeting the following specs:
   - MFM coded data.
   - Able to talk to the disk on a "control bus" or whatever (cyl #, etc).
   - Handles at least 19 heads.
   - The usual stuff (formatting, error checking, etc...)
   Even "I think AMD has one..." may be useful, but please elaborate.

2. Where can I get an SASI bus controller chip?
   Does it exist?

3. Which SCSI bus controller chip would you recommend?

-- 
"Don't think; let the machine do it for you!"
                                   -- E. C. Berkeley
Dept of Comp and Info Science	(uunet!mcvax!enea!liuida!obelix!p_e)
Univ of Linkoping, Sweden	(p_e@obelix.liu.se, p_e@obelix.UUCP)