11th Episode:-
The visit started with the standard sulk period when Flossie was turned on and was warming
up. We took the time to examine the half inch mag tape decks, looking along the line of
desks, for a deck that was working enough to try to load and run a tape. We will need to
do this soon as we plan to read the old tapes back and re populate Flossie's program library.
We found a deck that not only loaded and ran but also performed a stable and perfect rewind
at high speed, no wobbling servo arms, and a full parking of the arms at the end
of the rewind. We have one deck that works at least.
When we turned our attention to the machine now and found that we had no Control register
movement at all, we had allowed Flossie a long while to warm up, so it was fault finding
time again. Problem traced to package in 6C10, our 45 command now works again, so we
continued with the factory tests. Test 3.65 gave very strange results, and most of the
day was spent on this problem. To quote the Rhyme " Round and Round the Micro Order Flows,
Where they go Nobody knows " or at least we did not know for some time, but the Binary in
3D14 fixed it ( more jubilation )
Flossie now runs a simple test called GHOST, this is as follows
0000 = 370100 220001 ... / Load B reg with contents of 100 , set Dec point Reg to 1
0001 = 690101 660101 ... / Multiply reg B by Content of 101 , increment Location 101
0002 = 294000 004002 ... / pulse the speaker if 29 set , else loop on 29 set
0100 = 000000 001248 ... / Fixed data
0101 = 000000 000001 ... / Incremented data
After this event with even more Jubilation, we continued the factory test suite
to test number 4.3 this included a Sterling multiply, which worked first time.
10th Episode:-
Flossie warmed up quite quickly this time, but we soon found we had a new problem,
as we were unable to obey any instruction which ended in 6 . ie 16,26,36,56,66 all dead.
slowly traced down to package 3C19 us, We can now run test MI 26 or 66 functions ok.
Factory tests continued till we reached 3.50 then we found that bit 1 of digit 8
in the B register was suspect, traced to T1 package in 2C14. Test 3.55 located the
two bit in digit 7 of Register B, replaced 2D13. The machine is now running a loop
and even obeying a move or 45 function. we tried the following
45 0000
19 0100
And it worked moving 19 words from location zero ( our program area ) to location 100.
We tried a loop with function 69 ( the multiply command ) and it crashes the Control
registers after a few seconds.
At the end of the day it was big smiles all round and we left feeling that we were winning.
However those who know the 1301 computer, will tell you that there are all the Micro Orders
yet to get working, or to put it another way. HELL WAS WAITING FOR US.
Last factory test completed this trip was 3.60
9th Episode:-
The first visit after I returned from a cruise, only Roger and myself this time, ( we missed
having you around Tom ! ) work got under way to confirm we had access to some working store
and the three stores still worked after a suitable warm up period. We started to work through
the initial factory tests and found several problems. A G3 package in 3C1 part of the function
decode was giving us 80 ( drum ) instructions when none were there. Replacing that board
allowed us to have stops and non valid function decodes again, also the CR1->3 signal now
worked. Further decoder faults were spinning the pulse generator the wrong number of steps
and giving spurious results.
Some fun was had locating the sterling position counter and the decimal point register.
However the real problem here was that two bits of the decimal point register, were shorted
together, of course the short was under a cover, after removing the cover, a thump was
heard as Roger sprung the pins apart, another solid engineering solution applied.
A further problem which gave us a big surprise was the setting of the main stopped ( P3 )
binaries, this gave an odd symptom when we were in the area of the fault. The logic levels
on a 1301 are zero volts for a logic zero and -6 volts for a logic one. But this fault gave
us + 5 volts on some logic pins, this was eventually traced to unwrapped pins on the earth
supply to the G1 gating package in 6F21. Resolving this gave us the ability to actually
get the machine into run mode. The end of the day we took to wrapping in a lot of the
outstanding boards left on rubbers, this took some time and when we powered up, the
machine took a long while to overcome its cold faults, of course we blamed the work we
had just done. So it was with great relief that the machine finally started to shift
its Control Registers again, after the warm-up and to finish the day we ran our
first multi instruction loop. All of two words in store in locations zero and one.
The loop did not work correctly, but it did run the instructions and the stopped lamp
went out whilst this was running.
This is the first time flossie has obeyed any stored instructions in many a long year.
last factory test completed this trip is No 3.31.
8th Episode:-
This visit started with the news that we had received another wrapping tool, Thanks to
Mike Trueblood. So we were able to do a lot more in the time we had today, Tom was
along again and proved the new wrapping tool worked well around Bay 5, with a couple of
Control register bits in 5F20 and 5F21, also the clock amp. Some outstanding parity
problems were removed from BD0, A7 in RD1 replaced. Problems with store selection
were further resolved when we found an unwrapped pin on 10E16 pin5 ( how long has that
been unwrapped ?? ). Further work on store selection resulted in us replacing 10E6.
At the end of the day we had 3 out of 5 store units ( Barn Doors ) working, Numbers
3 and 4 still not playing the game. Time was allocated at the end of the day to do
some serious wrapping in , 8 boards in the barn doors, and 6 more in Bay 5. It was
a lot easier now we have two tools. The day also saw the test drive of another tool
which starts to solve a problem we found at visit 6, namely the breaking of
board rubbers, pure age as the rubber gets less flexible. We tried a home made solution
of a modified wallpaper scraper, it works, and puts less strain on the 25 way
rubber connector. Progress ( of sorts ) today .
7th Episode:-
This visit we welcomed to the project, the skills of Tom, who popped over to see
what we were doing and in no time, was wrapping in boards like the old days, so 3E21
was Toms' donation to the work. Just then Reg 'A' decided to blow up bit one of Digit
nine, T1 in 10A8 replaced, before it worked again.
We were able to make some progress today as the machine started with a 'sulk' ( needed
to warm up ) then started to give us some progress. We were able to talk to the first
400 words of IAS ( with some bit drop outs, of course ). But only after we removed
an enhanced decode for an address greater than 2000 words, by isolating the additional
address binary. Then we were able to talk to the second 400 words, so from 000 to 799
words were trying to work, they worked even better when we changed IAS read amps in
BD1/D3B2, BD2/D10B1, BD2/D2B8, BD2/D3B8, also the T1 in 9D22 and the T4 in 9B6 whilst
we were fault finding. To get the rest of the IAS working words 800 to 1999 will
need to be worked on though.
6th Episode:-
Work on 8 bits dropping out in CR's , around T1's in
locations 5F21,24 and 26, had to swap these more than once,
as the boards we replaced these with, were causing more
problems, eventually got reliable CR one, two and three
streaming, although this still needs testing at full speed.
Continued with System runaway problem, this machine has
always seemed to be 'BUSY' IAS Parity lights running and
DTU doing things at odd times, we often find that there
are extra signals around the A register when working on
problems, The DTU read and write logic was investigated in
the 4th Visit, and were found to be steady and going into
default status at switch on/off. Which only left the
possibility that the machine was fitted with a 1900 Tape
interface, which was defective. This was investigated and
yes it was running away, we worked on this for about half
an hour and decided that it was quicker to isolate the signal
causing the DTU to request transfers, and solve the source at
a later date, this would allow us to work on the basic machine
and resolve the primary problems. Pins 9J15 and 9J25 ( both pin
21 ) were isolated. Suddenly Flossie no longer had a headache,
the DTU was no longer busy and we could re-asses the basic
machine problems. The good news was that all the Programmed
Indicators now work ( most of the time )
Some basic functions were tried and Function 57 seems to be
reliable also 54 works, we then got greedy and tried a 42
function, it failed so we tried a 37 instead, no joy again
but we have not worked on the IAS Yet. Next step was into the
function decodes, after a lot of signal checks found 3E21
board duff. ' Blast it we changed that on the first visit '
so it was changed again. At the end of the day we were
happy that a major problem had been isolated, and we could
now pursue the basic machine problems.
Although we have reduced the number of boards on rubbers
we 'MUST WRAP IN THE REMAINING BOARDS STILL ON RUBBERS' !
There is also a problem with the rubbers themselves, as
time is now starting to reduce the flexibility and some
cracking can be detected at the moulded joints. A solution
may need to be found to this soon.
5th Episode:-
Dropping Bits in CR one, two and three, and unable to spin
the Control registers and do basic plus one between CR one and
three. So changed the following list of boards whilst
investigating: T1's in location 11G22, 5E26 and 5E17, G1's
in 5B13, 5B15, 5B16 and 5B17 also board in 5F23. We can now
do a plus one up to the value of 7 then we drop the 8 bit
and start again. We have changed lot of boards this time
round and the number of rubbered boards in the machine is
growing.
WE MUST WRAP IN THE LARGE QUANTITY OF BOARDS NOW ON RUBBERS !
4th Episode:-
Work continued on the CR1 to CR3 problems and the decode
of Non Valid Functions, i.e. STOP instructions now works, this
was traced to a T1 in 6C10. The system now looks as if the
main processor is being stopped all the time, some rechecking
of the previous, repair confirmed that now we had allowed the
decode the CPU was being held stopped by the Data Transfer
or Tape Control unit. Starting with the Address Book we
found that the signal we wanted ran between bays 4 and 9
at 6DR2 pin 17, checked out signal as ok there, so
considerable investigation followed,
including checking the status of the Read Control unit
and the Write Control unit in the DTU. At one point we had isolated
no less that five individual pins on a counter feed back
loop only to discover that the counter was a a digit
counter and the real status registers were in the next
bay. It was however proved that the read and write control
units did set to the correct status at power up, which means
we have interface control problems. Another board popped
during the power up/down sequences, whilst investigating
the above, an A1 in 13E12. So work continues at the next visit
to ensure the DTU is not interfering with the CPU so we
can do basic fault finding.
3rd Episode:-
Assorted problems at switch on are CR1 to CR3 gaining 2 bits
investigated and A4 in 13E13 replaced, cured this fault. We
also had failing to add one to completed instructions.
To resolve this later problem, the clocking of the control
registers was investigated, unfortunately the investigations
were with an oscilloscope which I was unfamiliar with, and the
result was that I wasted some considerable time, chasing my own tail.
However the lesson has been learnt and we wont make that mistake
again. The clock source on flossie has been modified, and the
impact on the logic with the drum resynchronization is that whole
chunks of the logic have been removed only a single board in
11E15 remains of the original logic. This was brought home to
me when I opened the console to discover that the variable clock
module, had been completely replaced. There was just a
potentiometer, where the module used to be. It has since been
verified that the clock source is good, just different !
2nd Episode:-
Before power up, it was decided we needed to check all the
cooling fans, so the machine was ready for the warmer weather.
Some units were beyond simple repair, with burnt out windings.
However the majority of fans responded well to stripping down
and lubrication of the bearings, work then started on existing
faults. Some problems had been identified with the shifting of
the Control Registers and after investigation the G1 in 5B9,
was changed to allow the CR's to rotate without corruption.
Work on the display selectors ( big bank of relays ) and the
setting encoders continued until we ran out of time. However
the majority of the displays, and setting bits now work.
1st Episode:-
This was mostly spent learning what the situation was, the state
of the machine, the suitability of spares. However some time was
spent in trying to resolve the multiple faults on this elderly
machine, and the board in 3E27 and in 3E21 were changed to
cure a fault where the Pulse Generator terminated early on all
orders.