DECmate III and Rainbow 100+

[Ethan Dicks]

On Tue, 22 Feb 2005 13:01:46 -0500, Paul Koning <pkoning at equallogic.com> wrote:
> Someone who understands floppies better might be able to deduce the
> correct timing parameters from the description in the PRO Technical
> Manual, but it's above my head.

Here's a table from a posting I made to Usenet in 1990...

"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


I wrote the original post in an effort to get someone with Manx to
twiddle a tool for the Amiga (I had Lattice C and the embedded
assembler stuff was entirely incompatible).  I do not recall what
document I got it from, but those numbers are from DEC describing the
byte-level format of an RX50 track.  Perhaps that would be helpful in
determining timing specifics, especially as they deviate from what PCs
traditionally use.

-ethan