10 Apr
2013
10 Apr
'13
11:20 p.m.
On 04/10/2013 02:25 AM, Arno Kletzander wrote:
Generally yes. TU58 file format is variable in
that the device appears to the system as
a blocked volume like disk (though slower). The transfer between the TU58 and
its host is serial data and the host request block(s) N and not that
much different than IDE or other intelligent disk system that uses a logial block
numbering
system. The tu58 does not know nor care what is in the 512 byte block. I've run CP/M
from TU58. ok, then TU58 emulation is, as I had hoped, going to float the boat for
me, at least until either more machines or media to be read crop up here. The
novelty weill wear off fast as a drive is only 256K, and its serial
line speed
and hence sloowwwwwwww...
Thats plenty of space for PDP-11 OSs.
Unfortunately I have no sound way to (mechanically) _mount_ and power those tiny little
5,25" disks in the '11 rack, that's why they're staying in the BA123.
I forgot the 300MB ESDI disk I got from a listmember together with a Webster Qbus
controller, I'll use that one if I ever want to run a large OS on the VSII.
I got a rack shelf and gutted a few PCs for the disk cage.
Suit yourself.
I've done them on the kitchen table. I must ahve done
at least 8 of them.
The only failures were not media related (controller dies on write and
blows the
track servo).
Keep in mind they have a filter and the spin-up is to clear the platters
and the dust that lands into the filter.
[large drives]
Physical large drive: any that want a lift or two people to install in
the rack.
Anything I can lift with one hand is small. Media capacity is a whole
different
matter.
Yep, however in the Mill on weekends the AC
was running lower and who
know how
many thermal cycles that machine had seen even before I got it.
If anything
the floppy is always a must on my systems as all my diags and
base RT11 systems are on that media (RX01, RX02, RX50, RX33, RX23).
Are they also
available in TU58 (file) format? A viable uVAX
is more than 150mb, (more like 300-500 for V7),
a loaded PDP11 is 30MB. Just difference is OS utilization.
So I guess it all boils
down on what one wants to run on it.
I've got one functional RD53 in it right now, and a second one I hope to revive at
some point in the future. Likely the bad
one has the stuck head problem
easy to fix. just upen it up and unstick it. There are more detailed instruction out
there.
I'v edone it many times and forget the whole you need a clean room thing, My first
salvage is near 25years old now.
I'd not want to try my luck, I'll work on
that one once I've got an aquarium type glove box set up. You can till
you have to format or defrag it. I keep a stack of sub 1gb
(from 50mb and up) SCSI drives for that reasonas well as a major
heap of MFM drives (St412s 10mb, St225s 20mb and Quantum
D540s 31mb). I just insert them and image copy to them as backup.
OK, seems we
mixed up logically and physically large drives here.
I have about none of the first, but several of the latter category amongst those in
question for the machines we're discussing here:
1(2)x RD53 5,25" MFM
1x 300MB 5,25" ESDI,
3x 5MB 14" RL01,
1x 10MB 14" RL02,
(2x 80MB 14" SMD) (I just have a lead on those yet) [TK50 tape subsystem]
Oh, It's been a while, I never use it. No need. If I need the data
preserved
I have it on disk and the system on UPS.
I meant save it for backups or other large data
needs as running diags
off it will be painfully slow. If its bad save it for parts, they are scarce,
usually the controller is fine and the drive is borked.
Understood. I'll find
out once I have a drive and media for it.
I've also already found out that the memory
board I'll be getting is 512k_Bytes_ (256kW) and does _not_ have BBU support.
?? BBU?? Unless you mean BBS7 (Io tends to use that).
Battery backup. Feeding it from an alternate 5V source to keep RAM content intact when
mains power is off.
One last
thing...
Heat! Qbus 11s produce a bit of that. That means fans must all work,
the location must not be dusty enough to load up the boards and local
temperature not excessively hot.
I fried a 11/23 board while working at the DEC Mill when they had an air
conditioner fail for the office area, when the room hit 96 (36c), cpu
went away, I had plenty of spares. So reliability and room temps are
coupled. Qbus 11s are fairly tolerent of conditions but any you find
are going to be old and may not like additional stress.
A hard "CPU
dead" damage without any warning? That's bad.
Good to know anyway, makes me want to add a system monitoring function
(temp and air flow) for emergency shutdown. Maybe something to design
a CD slot board for after all ;), at least before I'll run the machine
unattended.
Mine ran usually for months at a time, if the building AC hadn't failed
the cpu baord would still be in there (it is actually and repaired returned
to my spares box).
I also forgot something: I myself wouldn't have
thought of putting a NIC
(DEQNA or similar) in a pdp-11, probably just for the notion that back
in those days, computers were too few and far between to come up with the
concept of a Local Area Network. Obviously I was mistaken here, too.
PDP-11s were networked before NICs using DDCMP and sync lines. After NICS
Ether pipe. RT11 does little with it and its mostly useless for that
RSTS and RSX
in the later versions were full fledged nodes (DECnet Phase III).
Of course Unix had UUCP via serial lines and modems.
Allison