Date: Sun, 10 Jun 2001 12:25:04 -0600 From: Warner Losh <imp@village.org> To: Ian Dowse <iedowse@maths.tcd.ie> Cc: Mark Hittinger <bugs@freebsd.netcom.com>, hackers@FreeBSD.ORG Subject: Re: Strange request: Reading RX-50 (aka DEC Rainbow 100) disks Message-ID: <200106101825.f5AIP4l20899@billy-club.village.org> In-Reply-To: Your message of "Sun, 10 Jun 2001 17:14:56 BST." <200106101714.aa32440@salmon.maths.tcd.ie> References: <200106101714.aa32440@salmon.maths.tcd.ie>
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[[ Lots of details on how to do this deed, or at least the format
of the Rainbow disk, follow. Hit 'n' or 'd' if you don't care ]]
In message <200106101714.aa32440@salmon.maths.tcd.ie> Ian Dowse writes:
: The fdcontrol program allows most of the paramaters to be set to
: match the disks, but unfortunately it cannot set the sector offset.
: MSDOS disks sectors are numbered starting at 1 (the sector offset
: is 1), but it was common practice with old 8-bit CP/M-type systems
: to choose sector numbers starting at 0x41, 0x81 or other values.
That's OK. The Rainbow disks have sectors numbered 1 through 10, for
both CP/M disks and MS-DOS disks. This makes things easier to cope
with.
: The patch below is against RELENG_4 around Jan 2000, so it will
: need updating. I'm also not sure what sector offset the DEC Rainbow
: used - I think I have a Rainbow boot disk here, but I'd have to
: dig out a 5.25 floppy drive to check :-) Once you get the settings
: right, you can just dd the disk to an image file.
Well, here's the technical data I could find on the rainbow's disks
(boy, I'm glad I got the technical docs set with the unit, it was over
my head for the most part when I was 16, but it is perfectly readable
to me now). I'm not sure what to put for the "gap" "trans" or "f_gap"
parameters, so I'll include a little more info than most people would
generally want. However, it may prove useful to other people trying
to read different formats in the future. so here goes:
--------------
1 head (although I have drives with 2 heads)
10 sectors per track
80 tracks
250kB/s transfer rate
300rpm
Track Format:
Description No Bytes Contents
Pre ID Gap 47 0x4e
ID Fields
Sync 8 0
Mark 3 0xa1
Header IDAM 1 FE
Track Address 1 Track number (0-0x4f)
Side Number 1 0
Sector Address 1 Sector (1-10)
Bytes/sector code 1 0x2
CRC 1 Calc CRC [See note 1]
Pose ID Gap 22 0x4e
Data Fields
Sync 12 0
Mark 3 0xa1
Data DAM 1 0xfb
Data 512 <YourDataHere>
CRC 2 CRC over data
Post Amble 1 0
Pre_index gap 70 [2] 0x4e
Note 1: I think the length here should be 2 rather than 1 based on
other text
Note 2: "This field is written once per track until an index field is
encoutered" Whatever that means.
--------------
Finally, I have the actual disk drives (both the RX-50 and the TEAC
FD-55 which is a two sided version of the RX-50) that I could connect
for this project. Any thumbnail about how to add a new type of drive
to fd.c? What parameters do I need for it?
Finally, I have a few minor cleanups of my own for the floppy driver.
Mostly removing the last gasping vestiges of the ft driver that lived
in fd.c. I'd also like to move isa/fd.c into
dev/fd/fd{,_isa,_pccard}.c so we can eliminate one of the last
remaining NCARD variable useages. Anybody special I should talk to
before doing this? My guess is Joerg.
Warner
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