🚀 go-pugleaf

I have an "enhancement" to MSH, the messydisk.device in particular.  I
have been trying to read DEC RX-50 5-1/4" floppies for a long time now.
The drive I am using is a standard PC clone 5-1/4" drive attached to the
small circuit board found in the A1010 3-1/2" drive.  It works fine with
AmigaDOS, CrossDOS and MSH.  I want to read RX-50 floppies.  The chart
I have from the DEC manual looks like this...

"GAP 1"		GAP 1:		47  x  0x4E


		SYNCH:		8   x  0x00
		IDAM:		3   x  0xA1
				1   x  0xFE
		TRACK:		(physical track address)
		SIDE:		(physical side number)
		SECTR:		(physical sector number)
[Repeat once	SIZE:		1   x  0x02  (512 bytes per sector)
 per sector ]	2 CRC:		2      CRC bytes
		GAP 2:		22  x  0x4E
		SYNCH:		12  x  0x00
		DAM:		3   x  0xA1
				1   x  0xFB
 		DATA:		512 x  0xE5
		2 CRC:		2      CRC bytes
		GAP 3:		48  x  0x4E


		GAP 4:		6250 minus sum of bytes up to GAP 4 x 0x4E


The same chart lists PC floppies as follows...


"GAP 1"		GAP 1A:		80  x  0x4E
		SYNCH:		12  x  0x00
		INDEX:		3   x  0xC2
				1   x  0xFC
		GAP1B:		50  x  0x4E



		SYNCH:		12  x  0x00
		IDAM:		3   x  0xA1
				1   x  0xFE
		TRACK:		(physical track address)
		SIDE:		(physical side number)
		SECTR:		(physical sector number)
[Repeat once	SIZE:		1   x  0x02  (512 bytes per sector)
 per sector ]	2 CRC:		2      CRC bytes
		GAP 2:		22  x  0x4E
		SYNCH:		12  x  0x00
		DAM:		3   x  0xA1
				1   x  0xFB
 		DATA:		512 x  0xE5
		2 CRC:		2      CRC bytes
		GAP 3:		64  x  0x4E


		GAP 4:		6250 minus sum of bytes up to GAP 4 x 0x4E


As you can see, the formats are extremely familiar.  I would perform the
change myself, but I have Lattice, not Manx.  I would be very happy to see
a messydisk.device which supports that track format, and a diskette head
geometry of 10 sectors/track by 1 head by 80 tracks (400kb).  For someone
with Manx, the change is utterly trivial, but for me, almost impossible.
Once I can read the blocks on a diskette, I intend to write two new file
systems for the Amiga: RT-11 format and ODS-1 or ODS-2 FILES-11 format, 
so that I can directly read diskettes written on PDP-11s or VAXen.  The 
other possibility is to write tar floppies, but I still need to be able to
read the sectors.

Thanks much.

-ethan





--
Ethan R. Dicks       | ######  This signifies that the poster is a member in
Software Results Corp|   ##    good sitting of Inertia House: Bodies at rest.
940 Freeway Drive N. |   ##
Columbus OH    43229 | ######  "You get it, you're closer."