Posts by user "consub" [Posts: 7 Total up-votes: 5 Page: 1 of 1]¶

I have flitted through the threads, and have a few comments that might be of interest.
There were no classified components in the AICU, however there was company confidential in that we did not want the competition to have our lead, also there was an American embargo on delivering equipment with the 5400 series TTL logic integrated circuits which were milspec and chosen for their environmental screening.
Some of the printed circuit boards were 8-layer.
The program was contained in 512 lines of 24 bit instructions.

Hi Christian,I was a development engineer at Filton working on the AICU at first but ending up in charge of avionics test.
So as far as your AICU is concerned - I have handled all the boards extensively.
I first worked on the "A" model - the first manufactured box, followed by "A bar" (logically, not "A").
These did not have the doghouse connector on the front, and in order to see what was going on in the program, we made a strobe unit hard wired to the digital boards, this was followed by the connector on the front and an AICU test box.
When first switched on the whole unit rattled at high speed as all the relays chattered.
I spent several days adding decoupling capacitors on all the boards.
The birds nest chassis wiring was chosen to prevent cross- talk.
This was at the start of 1972, but I can still remember a lot of it.
Someone mentioned a prom change at Casablanca, I carried out a prom change there just before the C of A flight.
I am a volunteer at the Bristol Aero Collection, and we have just received a drawing cupboard with the AICS drawings.
We are at the moment documenting archives. One of the volunteers is Ted Talbot who I used to work with, and has been mentioned in posts.
Feel free to ask questions, I may remember the answers!

Hi Christian,I was a development engineer at Filton working on the AICU at first but ending up in charge of avionics test.
So as far as your AICU is concerned - I have handled all the boards extensively.
I first worked on the "A" model - the first manufactured box, followed by "A bar" (logically, not "A").
These did not have the doghouse connector on the front, and in order to see what was going on in the program, we made a strobe unit hard wired to the digital boards, this was followed by the connector on the front and an AICU test box.
When first switched on the whole unit rattled at high speed as all the relays chattered.
I spent several days adding decoupling capacitors on all the boards.
The birds nest chassis wiring was chosen to prevent cross- talk.
This was at the start of 1972, but I can still remember a lot of it.
Someone mentioned a prom change at Casablanca, I carried out a prom change there just before the C of A flight.
I am a volunteer at the Bristol Aero Collection, and we have just received a drawing cupboard with the AICS drawings.
We are at the moment documenting archives. One of the volunteers is Ted Talbot who I used to work with, and has been mentioned in posts.
Feel free to ask questions, I may remember the answers!

Hi Christian,
We chose the components for their environmental tests, and all the AICS components were subjected to acceptance testing when received, which was a bit of a problem sometimes because the BAC goods inwards system was so slow that some of the expensive ADC/DACs that were not quite good enough were returned to Harris, but were out of warranty by the time they were returned. The embargo was not just the 5400 TTL I/Cs but all milspec. components.
Its stretching my memory, but AICU1 was the ADC board, 2-5 were the processor, 6-10 were the prom boards. There was a bought in board (AICU 17 I think) that was supplied by ?????, that processed the sensor unit data.
The AICS was filled with redundancy, as well as the obvious 2 AICUs per intake, and 4 sensor units, the program calculated the output data with dummy inputs - twice, and if these were correct, the proper inputs were used and the result was output to the doors. On the analogue bit there were two channels for each output and at the end one output was compared with the other and if different a fail was produced.
We haven't opened the plan chests with the AICS drawings yet.
As well as the 8 AICUs on G-BOAF, we have the prototype AICU that was used on the AICS systems rig.

The reason that "birds nest wiring" was used for the backplane wiring on the AICU was indeed to prevent crosstalk.
I carried out a prom change at Cassablanca just days before the C of A flight, and used a prom blower that I carried out from Filton in my hand baggage together with boxes of proms, i remember the strange reaction by the customs man , until someone rescued me by telling him that I was taking them straight through to air side for Concorde. I programmed the proms by selecting the switches for the 8 bits of the line in the program for that particular prom, and then pressing the "blow" button that destroyed the fusible links in the input circuits of the prom. Of course all 64 lines of program in the prom that was changing had to be blown, even if only one line of program was changing. I carried out the programming on all 8 AICUs in 201, and the prom boards were laid out on a desk in the Air France office. Andre Turcat popped in to see what I was doing.

I have noticed that I missed a bit in my earlier reply, You will not find a CPU chip as you suggested ,instead an ALU was used with sub-routines it was a RISC before they were invented.].

Hi, for some strange reason I have only just come across this thread, I have looked at some of the early posts and can answer a few questions.
I was a development engineer on the AICU in 1972 and put the first AICU together and got it working.
I am now a volunteer at Aerospace Bristol and we have this box in the archives, it was used on the intake rig by Roger Taplin, half way down the hill at Filton,
There are no secret components used in the AICU, TTL 54 series was used, and these are the milspec version of the 74 series TTL. they are better quality, reliability and better tolerance, and more expesive. They were not available to all countries.
I worked with Ted Talbot at the time and in 1990 he recruited me to be the design manager for aircraft conversions and my first job was to manage the design of the VC10 tankers. There was mention of the leggy girl at Tangiers, that was Liz Pedley, a Cambridge maths graduate systems engineer, she married a GW systems engineer. I worked with her on many a long night sorting out program problems. I was the one who went to Casablanca to do the program program change to the AICUs that someone mentioned being removed from the aircraft and lined up on a desk in the Air France office. While I was there Turcat came in and sat at the table to watch.
I used a prom blower to blow the fusible links not a 9 volt battery, just as Liz would have done at Tangiers (the same prom blower)
Regarding the 1990s modifications to the AICU pcbs for obsolete components, I was requested by John Churchill, who designed the replacement boards, to give him some help. I was amazed that the test specs were still approved by my signature, which meant they had not changed since I moved on around 1978 when I moved to Stevenage. In about 1974ish we bought all the remaining proms as they were stopping being manufactured.
I will try and read the rest of the threads to see if anything else has been asked.