25 May
2007
25 May
'07
1:29 a.m.
On 5/24/07, Kevin Handy <kth at srv.net> wrote:
I recall that some of the drives from DEC came in a
6-bit
version for the pdp-8, pdp-10, etc and an 8-bit version for the
pdp-11, vax, etc. Was the RL02 like this?
No. As we've discussed earlier in this thread, the whole advantage of
using the RL02 (besides the fact that Charles has a PDP-11 controller
_and_ a PDP-8 controller ;-) is that there is *no host-based
difference* in the packs. Unlike the RK05, there is one and only one
format for RL01 and one and only one format for RL02 packs, no matter
if it is going into a PDP-8, PDP-11 or VAX. Unlike an RK05 or a
DECtape I, customers cannot format RL01 and RL02 packs (they use
embedded servo data), so there's not even any way to change it in the
field.
The filesystem is entirely platform dependent, but in this case,
Charles is using (has used) a standalone program to pull a working
RL02 image for the PDP-8 across a serial port _through_ a PDP-11 to an
RL02 pack. This would *not* work for an RK05, but, software
difficulties aside, is not impossible when the destination is an RL01
or RL02 pack.
Think of it like the difference in a PC between an ST506 drive and an
IDE drive - one can easily migrate the IDE drive from platform to
platform to platform because the host doesn't care about stuff at the
flux level, but the ST506-type drive sure does.
-ethan