mwilson@NOSC.ARPA (09/15/86)
I have a small problem which I hope that those of you out there in
net-land may be able to help me with....
I have an Ampro LB computer. The BIOS that Ampro supplies with the
machine ( currently v3.8 ) allows reading/writing from approximately sixty
different formats, with a utility included to format about half of them as
well. Problem: I have 2 96-tpi drives... and I need to format a 48-tpi
disk. The read/write routines use something called a "double-step bit" to
enable the 96 track drive to read a 48 track disk. This is done in the
BIOS, and the utilities include an option to set this bit.
Is there a way to cause the drives to "double-step" so that I can use
the MULTIFMT program, which does *not* include this option? Or is it
impossible? I would appreciate any insights.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Marc Wilson
ARPA: ...!crash!pnet01!mwilson@nosc ( preferred )
...!crash!pnet01!pro-sol!mwilson@nosc
UUCP: [ ihnp4 | cbosgd | sdcsvax | noscvax ]!crash!pnet01!mwilson@nosc
"The difference between science and the fuzzy subjects is that science
requires reasoning, while those other subjects merely require
scholarship."
-Lazarus Long
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Voorheis.es@xerox.ARPA (09/15/86)
A 96 tpi drive requires a floppy disk designed for 96 tpi (called high density). You can format a high density disk to 48 tpi but only on a 96 tpi drive. Subsequent writes on a 48 tpi drive will be unreliable.
mwilson@NOSC.ARPA (09/16/86)
What you are referring to is a quad density disk. As I said earlier, I
have been using normal DSDD and even SSDD disks in these drives witth no
problems. I have been trading files between the PC I was using at school and
my CP/M machine here at home, in both directions, with no problems.
There has *got* to be a way to do this!
--MarcMEAD@USC-ECLC.ARPA (Dick) (09/16/86)
Message-ID: <12239443092.24.MEAD@USC-ECLC.ARPA> Contrary to a previous message, you DON'T HAVE to have 96tpi floppies for a 96tpi drive. I use the cheapest SSSD $7.00 a box floppies in my SA465's which are 80trk DSDD.. the problem with formatting 48tpi disks on 96tpi drives is the track is narrower, and may not be readable by other 48tpi drives..\ -------
BEC.SHAPIN@USC-ECL.ARPA (Ted Shapin) (09/17/86)
Ampro has their own BBS at (408) 258-8128. Try asking them. -------
kenny@uiucdcsb.CS.UIUC.EDU (09/18/86)
Excuse me for posting this to the net, but NOSC says that mwilson is an unknown user. Date: Thu, 18 Sep 86 12:15:28 CDT From: kenny (Kevin Kenny) To: mwilson@NOSC.ARPA Subject: Writing 48 tpi on 96 tpi drives Cc: kenny We've been through this several times before... and I am already seeing the incorrect explanations of the compatibility problems between 48 tpi and 96 tpi drives flying. Here's a legitimate, simplified explanation. Please feel free to repost to the whole net if you see enough wrong ones go by (I've only seen two so far). The 96 tpi drives place two tracks in the space where a 48 tpi drive puts one: 48 TPI 96 TPI ------------------------------------------------------------------------ ################################|################################ ################################|################################ ################################| ################################|################################ ################################|################################ | ################################|################################ ################################|################################ ################################| ################################|################################ ################################|################################ etc. A 96 TPI drive can easily read a 48 TPI disk. The narrow head sits in the wide track ######## like ############################## ######## this ############################## ############################################ or ################################ like ###### ################################ this ###### and has no problems picking up the data. The problem comes when a 96 tpi drive WRITES a 48 tpi disk. If the disk is truly blank and unformatted, the 96 TPI head will write its narrow track and the 48 TPI can read it because there isn't anything else there to read: ############################## +----+ ############################## | | |wide| |head| +----+ But, if there's ANY data on the disk (say, for example, that the disk was formatted on a 48 TPI machine), then when the 96 TPI drive writes it, we'll have something like +----+ ################################|head|$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ ################################+----+$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ ###################################################################### ###################################################################### ###################################################################### so that two different streams of data appear in the area that the 48 TPI head will read. When the 48 TPI disk reads the data, it'll see some sort of bizarre average of the two and get read errors. (Don't flame, physicists and those who understand the recording format. I SAID this was a simplified explanation). Reformatting the disk on either style of drive won't help. Nor will duplicating the data on both half-tracks; they won't be precisely in sync. The only thing that can be done to REwrite a 48tpi disc on a 96tpi drive is run the whole shebang through a bulk degausser so that you again have a blank, truly blank disk. The degaussing is recommended in any case, since discs received from the manufacturer sometimes have test patterns left on them and aren't truly blank. Most 96tpi manufacturers don't want to contend with these issues, so they simply specify that you can read, but not write. () /\ .-.-. /\ Kevin Kenny ()() < > \ / (__) University of Illinois at Urbana-Champaign /\ \/ V /\ UUCP: {ihnp4,pur-ee,convex}!uiucdcs!kenny "When in doubt, CSNET: kenny@UIUC.CSNET lead trumps." ARPA: kenny@B.CS.UIUC.EDU (kenny@UIUC.ARPA)