Posted: Thu May 03, 2007 4:28 am Post subject: OUR Service Number
a two parter. Confirmation that I am not losing it.
ONE - when we joined we had no letter in front of our number and that number was six figures - to whit: mine was 687996 and they added V0 to it.
TWO The letter was the result of a computer algorithm performed on our service number and the letter was the CHECKSUM. This check was done using Modulus2.
I know this for a fact but it would be nice for someone to confirm it - not all 150 you need apply.
Verification of methodology
I would also like an explanation of the Modulus2 jiggery pokery as I cannot remember how it is done.
The Members List on the web site shows the official 6 figure numbers that we were allocated when we joined up. The prefix came later, although I can't remember when, how or why.
Isn't it odd how you can still remember your Service Number (well I can) from all those years ago yet have difficulty today with PINs, passwords, car registration, birthdays, in fact ANYTHING else????? _________________ TONY LINDON - click here for 100th Entry web site member's page
Last edited by admin on Sat Jul 28, 2007 6:33 pm; edited 1 time in total
The Members List on the web site shows the official 6 figure numbers that we were allocated when we joined up. The prefix came later, although I can't remember when, how or why.
Isn't it odd how you can still remember your Service Number (well I can) from all those years ago yet have difficulty today with PINs, passwords, car registration, birthdays, in fact ANYTHING else?????
The when was 1965, no idea about Jocks Modulus2 jiggery pokery
My service number, the 6 fig one is the only number I can always remember without hesitation. I guess its those years of 083 Sir, to get paid _________________ All the best
Geoff
Do it while you can and grow old disgracefully!
Verithingeoff Website Verithin Forum
The when was whilst we were at Locking and I am certain that it was in 1962 - It matters not except that it did happen and it was a CHECKSUM used by the PMC Computer. We got a small sheet of paper with the details on it and an explanation NOT a method of how
So really I am quite happy when it happen and Why it happened but not How??
The when was whilst we were at Locking and I am certain that it was in 1962 - It matters not except that it did happen and it was a CHECKSUM used by the PMC Computer. We got a small sheet of paper with the details on it and an explanation NOT a method of how
So really I am quite happy when it happen and Why it happened but not How??
Not 62, I quite clearly remember going to the general office at SHQ RAF Buchan to get the tatty bit of paper this was 1965 _________________ All the best
Geoff
Do it while you can and grow old disgracefully!
Verithingeoff Website Verithin Forum
I got lost after the first few lines, maths never was my strong point _________________ All the best
Geoff
Do it while you can and grow old disgracefully!
Verithingeoff Website Verithin Forum
Geoff, I think that I have to agree with you - The only thing I can think of is getting that paper 1250 and I confused it with that. I suppose if I sat and thought about it for a bit longer I would concur with you - By the way the maths are simple it's the bloody English that beats me lol??
Posted: Sun Jul 01, 2007 6:54 am Post subject: Service numbers
It is strange how we all seem to remember this number - I can't remember my National Insurance Number, passwords, car reg., kids ages. I still use the shoe brushes we were issued with and my number is on the side of each one! (Geoff, is it true you ar actually stood on a surfboard in this shot?)
I was looking out to sea the other day and on the horizon I think I saw you having that photo taken......but then again it might have been the Eddystone light house. _________________ Old age and treachery will overcome youth and skill.
Posted: Sun Jul 01, 2007 2:36 pm Post subject: Re: Service numbers
Keith Davies wrote:
It is strange how we all seem to remember this number - I can't remember my National Insurance Number, passwords, car reg., kids ages. I still use the shoe brushes we were issued with and my number is on the side of each one! (Geoff, is it true you ar actually stood on a surfboard in this shot?)
This is me at a younger age
_________________ All the best
Geoff
Do it while you can and grow old disgracefully!
Verithingeoff Website Verithin Forum
Posted: Tue Oct 21, 2008 10:26 pm Post subject: Service Number
The only excuse for this post is insanity- two weeks stuck in the house with the lerg does your brain in. But, hopefully Dai, at least it will give a simple answer to your long-standing question on 'modulus two jiggery pokery'. I had forgotton how it all works too- had to read up on it. Sorry it sounds so didactic. Some of the men on the 'Forces United' forum also seem to be interested in the logic behind the service number prefix: https://www.forcesreunited.org.uk.../displaytopic.asp?T=17178&p=1
Modulo Arithmetic
Modulo arithmetic only operates on positive integers. At an introductory level it is often called 'clock arithmetic'.
To illustrates the principle, consider a twelve-hour digital clock that just displays hours. It can only indicate times of 00, 01...10, 11 and then back to 00 (mathematically 12 O'clock is really 00 O'clock). Never mind how much time has passed, the clock can never display a time equal to or exceeding 12. And, of course, it cannot indicate a time less than 00, so there are no negative times. This is modulo 12 counting.
If it is 10 O'clock now and you wanted to know what the time would be a 100 hours in the future, you would add 10 to a 100 and get 110. Then you would keep subtracting 12 from 110 until you got a number less than 12, which is the modulus. The modulus would be the future time- in this case 02 O'clock. This is modulo 12 addition.
Here is an example of modulo two bitwise addition of two bytes (same as normal binary addition but the carry bits are ignored). In fact, it generates even parity:
11101010
11101100
00000110
Data integrity checks frequently use modulo arithmetic. A simple approach is to chop the data block up into pieces, say bytes, and then sum them using modulo two addition. After adding all the bytes together in this way, you end up with a byte, the checksum, which holds information (in fact vertical even parity) about the data. For practical reasons, each bit in the checksum is normally inverted (odd parity) before being attached to the data.
The appended checksum then allows the data to be roughly checked for corruption. It is just a matter of repeating the procedure and ensuring that the modulo-two-sum of the data equals the checksum value.
Our Service Number
Around December 1964, two extra characters were stuck on the front of our original six-numeric service number. The most significant character was a capital letter that varied from service number to service number. The second most significant character was always zero.
It would be sensible for the letter to embody some form of error checking. But, there is a slight complication at the binary level because the character must be printable and unambiguous to the users. This means that the 'non-printing' character codes must be excluded. The RAF also decided to omit the lowercase letters and the numbers. It would also be best to exclude 'I', and 'O', in the interests of clarity. This leaves only 24 characters to represent any checksum. Because of the excluded capital letters, the codes for the remaining capital letters would not be in continuous binary order in any standard coding scheme (e.g. Baudot, ITA2, BCDIC, EBCDIC, IA5, ASCII), so the equivalent of a 24 deep look-up table would be required to translate the checksum into a suitable character code.
After all that, the capital letter in our service number may be derived as follows:
1) Take the binary values for the 7 least significant numbers (according to the coding standard used).
2) Sum the 7 binary values using modulo two bit-wise addition, to arrive at a total.
3) Repeatedly subtract 24(dec) from the total until a value less than 24 is obtained (the modulus).
4) Use the modulus to get the letter code from the look-up table.
Dai's Service Number
Here is your service number given the tratment (apart from the final look-up):
SNo
b8(P)
b7
b6
b5
b4
b3
b2
b1
0
1
0
1
1
0
0
0
0
6
1
0
1
1
0
1
1
0
8
0
0
1
1
1
0
0
0
7
0
0
1
1
0
1
1
1
9
1
0
1
1
1
0
0
1
9
1
0
1
1
1
0
0
1
6
1
0
1
1
0
1
1
0
Sum
1
0
1
1
1
1
1
1
This assumes 7 bit ASCII encoding with an eigth bit (horizontal odd parity) tacked on to make up a byte for each character. Having arrived at the value for the checksum, the problen is to then convert that to a letter, in your case 'V'.
Of course, this is all speculation: I tried to get the exact method but nothing worked on actual service numbers- there are many variables. But, may be, the letter is just a letter and doesn't represent a checksum after all.
Last edited by chuck shenton on Sat Oct 25, 2008 11:21 pm; edited 62 times in total
Despite a couple of terms of extra maths, I'm still a dullard in that respect. How I managed to do all the computer courses is still something that amazes me. I read your stuff Chuck, and I hope the last line is the correct conclusion.........083 SIR!!!!!! _________________ All the best
Geoff
Do it while you can and grow old disgracefully!
Verithingeoff Website Verithin Forum
I think it was our little brain box , Jeff Fowler , that worked out for us how our service number prefixes came about .
It took a while , but he managed to get everybody present in the billet at the time , correct first go !
Sadly , I believe he is no longer with us . I expect he is standing at the pearly gates upstairs awaiting our arrivals , with a new prefix for our service numbers !
Do we get NEW service numbers issued on arrival upstairs , I wonder ?
Hi Monty, good to see you about again
Chuck, I have had a sort out in Photobucket and the links have been lost, If I get a mo. I'll re post them _________________ All the best
Geoff
Do it while you can and grow old disgracefully!
Verithingeoff Website Verithin Forum
Hmm, now you mention it, I can vaguely remember Jeff Fowler decoding our service number. He was a very clever fellow- top of the Entry in the finals I believe. On that basis we must have been given the prefix before leaving Locking, but, like Geoff, I remember collecting the tatty note after leaving Locking. In my case it was from Church Fenton General Office around Jan 1965. We were probably told the code at Locking in Dec 1964 and then formally notified in Jan 1965.
You may be lucky, but I don't think I will be going 'upstairs'.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
FAQ
Search
Memberlist
Usergroups
Join! (free) 
Profile
Log in to check your private messages
Log in
- The only thing I can think of is getting that paper 1250 and I confused it with that. I suppose if I sat and thought about it for a bit longer I would concur with you - By the way the maths are simple it's the bloody English that beats me 
lol??
