24B Page 117
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| Thurlow tapes of the second kind. |
Such tapes are easily made on Miles: the first character of each batch of 1271 places on the cipher tape is marked. For a Thurlow tape of the second kind 1st, 2nd, 3rd, 4th, 5th marks are placed in the eyes of the 1st, 2nd, 3rd, 4th, 5th transmitters of Miles.
Z1 and Z2 from the nth transmitter are added into the nth impulse of the distributor.
When 1271 characters have been punched the machine is stopped, the 2nd mark on the cipher tape will be in the 1st eye, the 3rd in the 2nd eye and so on (if not, something is wrong - a useful check). The 6th, 7th, 8th, 9th, 10th marks are now placed in the 1st, 2nd, 3rd, 4th, 5th eyes, the machine restarted and so on.
The second step is to difference the Thurlow tape just made on Garbo (with normal deltaing, not the special rectangle device) and print out, steckering
| / to 0 | |||||
| all | 1 | cross | letters | 2 | 1 |
| " | 2 | " | " | " | 2 |
| " | 3 | " | " | " | 3 |
| " | 4 | " | " | " | 4 |
| " | 5 | " | " | " | 5 |
As in an ordinary Garbo rectangle the 32nd row is printed immediately below the 1st and so on.
The entry for a cell is now the depth minus twice the sum of the scores printed. Otherwise the entering is the same as for a Garbo rectangle. Note: Alternatively, if Miles A is available, a deltaed Thurlow tape can be made: this is printed out without deltaing on Garbo or Junior.
(For Thurlow tapes R4 p 71, Wheel Man's log book II, 103.)
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