Path: utzoo!utgpu!water!watmath!clyde!att!whuts!homxb!genesis!hotlr!anumb!adh
From: adh@anumb.UUCP (a.d.hay)
Newsgroups: comp.sys.att
Subject: Re: Well, maybe not so easy...; HwNote04
Keywords: 7300 3b1 HD upgrade
Message-ID: <369@anumb.UUCP>
Date: 18 Oct 88 13:27:45 GMT
References: <365@uncle.UUCP>
Reply-To: adh@anumb.UUCP (a.d.hay)
Organization: AT&T Bell Laboratories - MV
Lines: 48

In article <365@uncle.UUCP> jbm@uncle.UUCP (John B. Milton) writes:
[]
-->Gary Sanders has the board I already got working. He will soon be stress
-->testing a setup with two drives. He has the second drive exteral in a PC box.
-->He also tells me some interesting news that Western Digital has a new hard
-->disk controller chip that does RLL and is almost pin compatable with the WD1010.
-->He'll post the details when he gets the data sheet.

the HD chip gary's thinking of is probably the WD50C12.
it will do MFM, RLL, and ESDI/NRZ; it also can be programmed to
control 2 drives/16 heads instead of 4/8. in addition to being almost
pin-compatible with the 2010, it is software-compatible.
he should also get a data sheet on the WD10C22B, a front-end chip for
the 50C12 with ST506/412 drives. it is switched by the 50C12 for
MFM/RLL.
i looked into this some time ago, and gave up for 3 reasons:
laziness, sloth, and nothing else (:^>).
actually, the *&@$%#^ gd driver is embedded in the kernel, and i don't
know how to write a driver anyway.

-->Jan Isley (jan@bagend) says he will be looking into adding a 1.2M floppy soon.
-->Right now he's having problems getting postings out onto the net. The 1.2M
-->floppy looks like it might be possible because the Western Digital Floppy Disk
-->Controller has a pin on it to switch from 5.25" to 8" disk drives. The high
-->density floppy drives look just like 8" drives I'm told. There is also no
-->problem with changeing the pin under software control. I have an S-100 Z-80
-->system that has another FDC from the 279x series, the 2793. I have used the
-->S-100 with both 5.25" and 8" at the same time. Of course having two floppies
-->would at least require a new gd driver.

as for multiple floppies/densities, i have a data sheet for the 279X
also. it looks to me like the 5"/8" pin only changes *read* setup; you
have to change the chip clock for write setup.  (clarification -- there
is one pin that is used either for a side-select *output*, *OR* an
xmtclk divide select *input*, depending on the chip)
another detail - the gd will have to go through an "autobaud" sequence
on reading/mounting a floppy because the floppy may be SD, DD, or QD,
and it will have to extract the number of tracks from the floppy VHB
so it can distinguish between 48tpi and 96tpi disks.
then there are floppy tapes...

...anyone have kernel src?

-- 
Andrew Hay		+------------------------------------------------------+
Holistic Specialist	| I was reading my name on the glass of my office door |
AT&T-BL Ward Hill MA	| and listening to the staccato of rain on my desktop- |
mvuxq.att.com!adh	+------------------------------------------------------+