--- Density ---

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3 total messages Started by nep.pgelhausen Wed, 19 Feb 1986 01:09

#2513

Author: nep.pgelhausen
Date: Wed, 19 Feb 1986 01:09

21 lines
1519 bytes

In a reply to a recent query about disk densities, Rob Botwin said
that the PERCOM density command format was copied by everyone including
Atari.  Sorry to say, from what I understand, Atari is the ONLY company
making disk drives for the Atari which does NOT follow this standard.

This is definately true for the 810.  I cannot vouch for the 1050, but
as far as I know it also is 'dumb' as far as density settings.  It can
read single density format disks, but unless upgraded, it cannot read
or write true double density.  Nor can you use the PERCOM commands to
ask it it's current density or reset it. 

I assume that the "read the first sector" method that David suggested
was meant for 1050 disk drives.  (NOTE: David Young, (sorry)).  

If I am misteaken in any of these statements or beliefs, please someone,
correct me.

			-Richard Hartman
			max.hartman@ames-vmsb
------

Re: --- Density ---

#2564

Author: R.BOTWIN
Date: Tue, 25 Feb 1986 15:35

55 lines
2657 bytes


[]
In response to numerous requests, I am posting some info on drive density
switching:

To change density, you must call SIO, after setting up the IOCB as follows:

Device=$31   (D)
Unit= Drive #
Command= $4E (N) to READ CONFIG
       = $4F (O) to WRITE CONFIG

Byte Count = 12
Aux Bytes= (not normally used, but some DOS's use as part of formatting)

Also a "P" command is supported by some drives (like INDUS) to reconfigure
on demand prior to formatting.

The bytes transferred are:

byte 0: Tracks per side (40 std)
     1: Drive step rate (west. dig. std....0 fast 3 slow)
     2: zero (hi-byte of sectors/trk)
     3: sectors per track (18 for std...26 for 1050 mode)
     4: number of sides (0=single 1=double)
     5:  disk type: 
         bit 2: (0=single den, 1=double den)
         bit 1: (0=5-1/4"      1=8 ")
     6: hi-byte bytes/sector  (0 for 810 compat)
     7: lo-byte bytes/sector  (128 for 810   256 for double den std)
     8: translation byte:
         bit 7: (1=40 trk on 80 trk drive)
         bit 6: always 1 ...indicates drive present
         bit 1: 1= make boot sectors (1-3) full size
         bit 0: 1=sectors numbered 0-17 not 1-18
     9-11: undefined

These bytes are transferred TO the progran on a read config, modifications
may be made, and a WRITE CONFIG will change the desired options.

The comment about it not working on an 810 is specious....Obviously
these commands will only work on configurable drives...like PERCOM, INDUS,
ATR8000 controller, etc.

On more note; thos using MYDOS are prompted for these options when using
menu selection P from DOS...It internally generates the CONFIG command
and executes it. I have placed a BASIC program to configure drives on
some ATARI bulletin boards, but I'd have to look for a copy now...
It's been several years since I wrote it!

	Rob Botwin, N2FC
    .....{utah-cs|seismo|decvax}!harpo!eagle!houxm!mtuxo!mtuxn!rb
	ATT/IS Labs (201) 577-5016 (Cornet 8-270-5016)
	FJ 1B-130

Re: --- Density ---

#2568

Author: Nicholas J. DiMasi Jr.
Date: Wed, 26 Feb 1986 20:18

10 lines
1147 bytes

I would like to add that MYDOS is not the only DOS that provides
a command to configure (incl. switch density) such disk drives.
DOS XL (from OSS) provides a CONFIG command that lets you specify
single or double density and single or double sided for each
drive.  (My Percom drives will change density, but are only
single sided, so I can't vouch for the usefulness of the 
single/double-sided switching.)

					Nick DiMasi
					Lachman Associates, Inc.

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