On 12/19/2011 11:00 AM, Ethan Dicks wrote:
On Mon, Dec 19, 2011 at 1:28 PM, jim s<jws at
jwsss.com> wrote:
I'm curious how many sectors / track these
packs were supposed to have. The
photo of the bottom clearly showed it was> 12 which is what I thought DEC
used.
Are you perhaps thinking of RK05 cartridges? Those have visible
notches on the hub and come in 12-sector versions for 16-bit hosts and
16-sector versions for 12-bit hosts (same number of bits per track,
just grouped differently).
I'm looking at the auction on epay
330656553200
which calls them out as RL02K packs and has a photo of the bottom of one of the packs.
The packs hub has what appears to be sector notches.
I didn't know that these 14" drives ever used the embedded servo technology. I
only encountered that on the 8" and 5" hard drive disks, and of course
winchesters began being built with that technology rather than using a servo surface.
I though these were either 2311 or 2315 IBM type technology, but one could use the
embedded technology, I suppose with 14" drives, though the real estate at the arial
density would be as large or larger than the data fields with the oxides they were using.
As I said the comment was primarily on a photo on the above auction, which you probably
need to look at and comment on while the pictures are up. I'm not sure how to pass a
photo along on this list. I'll grab them off in case the epay poster is hosting them
on their own servers.
The RL01 and RL02 use embedded servo data (with no way
to restore that
in the field, so bulk-erased packs are useless in DEC drives). The
stickers and handles are color coded (brown vs blue). All other
external indicators are the same between the two types of packs.
http://www.pdp-11.nl/peripherals/disk/rl-info.html
the Microdata systems always used 24 / track with
256 byte sectors.
Jim
40 sectors per track, 256 byte sectors. RL01s have 256 tracks per
surface, RL02s have 512 tracks per surface (different heads, and
either different boards inside, or same boards but different jumper
settings depending on the revision). As a result, one can rig RL02s
to (safely) read RL01 packs, but I've never done it myself).
-ethan
thanks for the reply
JIm