21 Mar
2015
21 Mar
'15
3:21 p.m.
On 03/21/2015 02:58 PM, Lawrence Wilkinson wrote:
The plus side is that you can pretty well replace a module
with a few transistors/diodes/resistors, if you have the
manual that shows you what is inside each one. Also, the
same SLT card will be used in many places so it's easy to
swap them around. For the Model 30 there was a manual that
showed where each card was used, which facilitated this
swapping. Of course there were odd cards that only
appeared once or twice. Yes, this is true, and I was pretty amazed at your ability
to fix the 360/30 you had. But, time has been continuously
taking its toll. On the other hand, I was amazed to see on
Wikipedia that 4 1800's were still running in 2010. There
were no SLT parts available after sometime around 1980, and
IBM was supposed to get as much stuff back so they could
support the FAA's 9020 computers, which were slightly
modified 360/50's and /65's. I'm pretty amazed they could
keep those 1800's running for an additional 30 years. Maybe
they were a lot more reliable than I thought, from my 360
experience.
I don't know. The power system in the 360's was different.
They used a "converter-inverter" that changed mains power to
DC, than inverted it to single-phase 120 V, 2500 Hz sine
wave. This was fed to remarkably small linear
transformer/rectifier/regulator modules. The downfall of
this was there was little energy storage for momentary line
fluctuations, so any tiny blip on the mains caused a system
crash.
The 1800 may have been designed differently to work in a
known-bad power environment. it seems to have some quite
large bulk supplies of relatively low power output, each.
There is a mention in the FE manual about making sure the
machine has the right 50 Hz or 60 Hz transformers. I
believe the 360s only needed to have one card swapped in the
converter-inverter to set up the SCR preregulator timing for
the right frequency. So, anyway, it is not clear the power
supplies are of the switching type. but, in any case, they
need to be checked before power is applied, or the filter
caps could pop.
Yup, I think you were VERY lucky, too! It was not hard to
make a big mess with the old 14" disk drives, the heads were
very easy to scratch.
Jon
On 21/03/15 19:39, Jon Elson wrote:
I think it is going to need more tender loving care that
that! It is now over 40 year old. Seals and hoses will
have dried out and become brittle.
On 03/21/2015 01:47 PM, Johannes Thelen wrote:
Yes, hydraulic
actuator. Assuming it hasn't run for a long
time then flushing and replacing the hydraulic fluid would
be necessary. Thanks Jon for tips!
No, that is not option, I mean 2311 is have to get back
to life ;) I think use ultrasonic or carbon ice
cleaning for 2311 and disk packs. Both are quire gentle
cleaning methods.
You have to be very careful with anything that requires
temperature extremes. Can anybody verify the 2311 uses
the hydraulic head positioner? If the oxide coating of
the packs has deteriorated, which I think is quite
possible, then the disks will not be usable. Anybody else
have experience with 14" disk packs from 40" years ago?
So, the likelihood of the CPU actually working after
FORTY years of storage is pretty small. There are, of
course, no replacements for SLT modules, as IBM stopped
making them in the late 1960's! It was a form of
diode-transistor logic, and not terribly dense. A single
flip-flop would not fit in one SLT module, it took at
least 2, and the usual scheme was to integrate some
steering gates with it and ended up with about 4 modules
to implement the typical register bit. They didn't use
what we think of today as a FF, they used D latches, as
it was simpler to implement, but required several clock
phases. One clock phase to latch input data to the ALU,
wait for the ALU to settle, then a pulse to latch the
result out of the ALU.
The power supplies would be the first thing to work on -
they'll be switchers and have the potential to make a very
large bang. >> I like to dump core and all disc packs for
future uses
>> ( = make original configuration).
I wouldn't
worry about what is left in core, it would be
interesting, but you might have to do a lot of testing
and repair before enough of the machine is working to
read it out.
Be very careful with the disk drives. If you even get a
scratch on the heads, you will not be able to replace
them. Also, if anything at all happens to the heads, you
will need an alignment pack to realign any replaced
heads. Do you have ANY experience with old-school
mainframe equipment? If you think you will just dust
this thing off, mount the disk packs and fire it up, you
are quite crazy!
I got away with it, but the Model 30 was only 10 (or
fewer) years out of service. By defeating interlocks it's
probably possible to get a 2311 to spin up without a pack
and have it load the heads (with something soft between
them!) to check head loading and cylinder actuation. I'm
not sure what diagnostic facilities exist for the 1800,
but the 2841 controller had microcode routines to manually
test drives.