Path: utzoo!utgpu!water!watmath!clyde!att!whuts!homxb!mtuxo!mtgzz!drutx!druhi!med
From: med@druhi.ATT.COM (Myron Drapal)
Newsgroups: comp.sys.atari.st
Subject: Re: 5.25 help
Summary: buffering.... a must.
Message-ID: <3266@druhi.ATT.COM>
Date: 23 Jul 88 04:50:35 GMT
References: <880721-140208-4503@Xerox>
Organization: AT&T, Denver, CO
Lines: 27

In article <880721-140208-4503@Xerox>, "Robert_L._White.ESXC15"@XEROX.COM writes:
> The problems are:
> 		2) I have written a "c" program to format for 40 tracks,
>		   and that works with no problems (no errors returned),
>		   except that I get allot of disk errors when reading or
>		   writing. i.e. data on disk may be damaged, cancel,retry.
>		   Sometimes a retry will work, but not allways.
> 		3) The really strange thing is, when I format a 5.25 on a PC,
>		   I have no problems reading or writing to that disk on my 
> 		   5.25 drive on my ST. Wierd!
> 
> Any help would be nice
> Thanks
> Bob White, Xerox corp.

In order to get most (if not all) 5.25 inch drives to work consistently
on the ST, you *must* buffer the drive selects (a and b) and the side
select signals from the ST.  They are driven (poor choice of words ;-))
by the wimpy GI sound chip, which can barely drive the 10 inches of
cable, let alone the inputs of the drive.  Also, make sure to remove the
termination (try this first, it may be just enough to make it work).  If
you set the two undocumented seek rate varaibles, and do this buffering
(non-inverting, I think a 74244, but look it up first), you should have
no problems.
					Myron Drapal
					AT&T Denver
					ihnp4!druhi!med