```
APPENDIX 1
HOLLERITH TIMING
In order to link the operation of the DEUCE with the Hollerith Read
and Punch, it is useful to know the time in Major Cycles between various
operations on the two Machines. A chart of these is attached. The column
referring to the Reader will be explained, that for the Punch being very
similar.

(a) From the time of the Hollerith one-shot, Source 0 continues to give
the current row for a period of 2 Major Cycles. From 6 Major Cycles
onwards Source 0 gives zeros, representing the space between rows.

(b) Not less than 15 and not more than 21 Major Cycles elapse between
successive one-shots from the same cards. Thus, computations which
take place between rows should not last more than 15 Major Cycles
if one-shots are not to be missed.

(c) When cards are following each other at maximum speed, the first one-
shot of one card follows the last one-shot of the previous card after
an interval of not less than 80 and not more than 100 Major Cycles.
Computations which take place between cards should not last more than
80 Major Cycles if first  one-shots on  each card are not to be missed.

(d) Between the 11th one-shot and the beginning of TIL there is a period
of at least 11 Major Cycles. From the beginning of TIL to the 12th
one-shot there are not less than 2 and not more than 7 Major Cycles.
After the 12th one-shot TIL lasts for not less than 18 and not more
than 23 Major Cycles. Also, after a P54 on the 12th row, or 9-24X
using the 12th row stopper, TIL will certainly be off after 23 Major
Cycles. For continuous reading, the first one-shot of the next card
is at least 57 Major Cycles after the end of TIL. Source 0 does not
revert to the I.D. between cards, provided cards are running contin-
uously. Otherwise, Source 0 reverts to the ID lamps within 13 Major
Cycles after the 12th one-shot.

(e) When the Read has been idle, there is a period of at least 130 Major
Cycles between calling for a Read ("12-24") and the arrival of the
first one-shot.

(f) When the reader is cleared by a P34 on the last row of a card it may
(g) be recalled immediately by the instruction 12-24 (using the single-
shot from the last row if desired).

If however the reader is cleared, (either by a P34 or by an instruction
9-24) before the last row of a card it should not be recalled within
2 Major Cycles, or further rows of the same card will be read as if
the TIL signal will not be inhibited).

(h) If the reader is cleared within 40 Major Cycles after the S.S. from
the last row of a card, no further cards will be fed.

If the reader is cleared between 40 and 70 Major Cycles after the
S.S. from the last row of a card, a further card may be fed, but
will not be read and will give a 'MISSED CARD' alarm.

If the reader is cleared more than 70 Major Cycles after the S.S.
from the last row of a card, but before the first S.S. of the next
card, a further card will be fed, and not read, without giving a
MISSED CARD' alarm.

(j) In order to inhibit the S.S. from the subsequent row of a card,
reader or punch must be cleared within 13 and 35 Major Cycles
respectively of the stop instruction for a given row.

(k) If a transfer to destination 29 is made more than 20 Major Cycles
after the stop instruction for arty row other than the last, the
word sent will be successfully punched on the next row, unless an
instruction 8-24 precedes the time of the next row.

(l) This is similar to a 'MISSED CARD' on the Reader. If the punch is
not cleared within 20 Major Cycles of the last row of a card,
another card will pass through the punch. This card will be blank
in the DEUCE field but will carry punching in the Job and card
numbering sections.

(m) If a programme finishes with the punch and then uses D29 for the
O.S. lights there is a possibility that the first transfer to D29
after the punch is cleared will punch the next row of the card.
This will not occur if the punch is cleared within 24 Major Cycles
from the last row on which punching is required.

NS-y-16/5-56

```
APPENDIX 1 CONT'D

HOLLERITH TIMING TABLE