26 Aug
2014
26 Aug
'14
7:05 a.m.
On Aug 26, 2014, at 3:22 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
And then there's this...
http://www.columbia.edu/cu/computinghistory/rp06.html
http://www.columbia.edu/cu/computinghistory/rp04.html
... and this fragment...
"The RP04 and RP05's used the same pack. The RP06 was twice the density
so I'd figure the servo tracks were different. Twice as many cylinders
IIRC.
RP06 - 815 Cyl. 20 heads 19 recording surfaces.
The RP06 is equivalent to the IBM 3330 Mod II.
RP04/RP05 - 411 Cyl 20 heads 19 recording surfaces..
The RP04 or RP05 is equivalent to the IBM 3330 Mod I.
RP05 is a half-density RP06 made by Memorex. The RP04 was an ISS/Sperry
drive. The RP05 was originally designated RP04-II before production and
marketing."
So the RP04-RP05-RP06 are one drive series, and the RP02-RP03 are another.
RP04 and RP05 are in fact compatible; the same pack can be read and written on both. The
RP06 pack is mechanically the same, but the layout is different and it can only be
read/written on an RP06.
By the way, when drives are described as ?equivalent to the IBM 3330?, chances are that
means mechanically identical. The format is different, and you?re quite unlikely to be
able to read a pack for the one on the other drive. (Well, not unless the drive doing the
reading is very forgiving about foreign formats, which I don?t believe is the normal
practice.) IBM used variable length sectors and, if requested, keyed sectors, on the IBM
360 and 370 series systems. DEC used 512 or similar fixed length sectors. CDC used this
kind of drives too: a CDC 844-21 is the same thing as an RP04, pretty much, but it uses
sectors of 322 12-bit words.
paul
On Tue, Aug 26, 2014 at 3:15 AM, Ethan Dicks
<ethan.dicks at gmail.com> wrote:
> On Tue, Aug 26, 2014 at 2:37 AM, Pontus Pihlgren <pontus at update.uu.se>
wrote:
>> But I'm curious whether later RP drives are backwards compatible, could
>> an RP06 be used?
>
> I wouldn't think so?
Correct. RP03 is physically very different from the RP04/5/6 packs. The recorded area is
much wider. The IBM 2314 was mentioned as comparable.
You?re going to need an RP03, or a spin table.
Also, was the RP-drives DEC designs or rebadged
drives from someone else?
ISTR the RP02/RP03 were a Memorex drive, and probably the RP04 and
RP06 but I'm not as sure...