Appendix 2: Notes for Programmers who wish to prepare their own tapes and/or run them on the machine personally

• Preparation of Tapes
• Library programme tapes
• Output tapes
• Operation of the Machine

Preparation of Tapes

The programme and data are presented to the machine as one or more lengths of perforated paper tape which are scanned by the photo-electric reader - the input unit of the machine. These tapes are prepared on a manual keyboard perforator, the keys of which correspond to the standard symbols listed in Part 1.

The material is punched in the conventional manner, namely from left to right and down the column. Each line must be followed by two special symbols CR (carriage return) and LF (line feed). Mistakes may be overpunched with the erase symbol. There is also a space symbol SP which corresponds to a space one character wide. Numbers on the data tape which are written on the same line must be separated by at least two spaces.

If the programme is to be run from time to time with different sets of data, then it will be convenient to prepare the main programme and the data as physically distinct tapes. For the same reason a steering programme will usually be prepared as a separate tape. All such tapes should be terminated by ® CR LF ( for reasons explained below) and must of course be presented in the correct logical order corresponding to the programme layout.

Library programme tapes

Although library programmes could be presented to the machine as physically distinct tapes as described above, it is not a good idea to festoon the console of the machine with a large number of different tapes. In order to keep the number of physically distinct tapes to a minimum, all library programmes should be copied on to (and so form part of) the main programme tape. The library copies will be found to be headed with a title sequence:

title
programme - n

which should not be confused with the directive:

programme - n.

The latter is necessary to the assembly of the programme, while the former can be omitted from the final problem tape if desired. (For this purpose it is separated from the programme proper by a length of blank tape.)

Output tapes

The machine itself produces perforated tape (which can be printed on a teleprinter) when it reads a title sequence or when it executes a print (or ?) instruction or a 620,n instruction. A tape produced exclusively by using print (or ?) instructions can be subsequently used as a data tape.

Operation of the Machine

The Autocode programme is a binary tape and is put into the machine by means of Teleinput. It occupies sectors 0 to 31 and 80 to 127 inclusive, which should then be isolated. The latter group corresponds to the negative auxiliary locations -1, -2, ... .., -1536, and can be used as such if necessary, although this means dispensing with the rmp facility, A separate tape is provided for the matrix operations (other than Æ8, Æ9. Æ10 which are on the main Autocode tape) - which overwrites sectors 480 to 511 inclusive. These are normally occupied by the Engineers' Test routines and for this reason the maintenance engineer should be informed that they have been overwritten.

As already explained it is a convention that all physically distinct tapes (programme or data) should be terminated with ® CR LF. Should the machine attempt to scan this sequence, the loudspeaker will give one of two characteristic signals, depending on whether the scanning instruction was a read (a rapidly varying note) or an rmp (slowly varying note). In either case it signifies to the operator that the machine is calling for a new tape. After reloading the reader the machine can be made to continue by pressing handswitch 9. When splicing two tapes together the sequence should be omitted, otherwise the operator will have to stand by to surmount it manually.

There is also a halt instruction which stops the programme and gives a medium speed intermittent note on the loudspeaker. This is surmounted in the same way by pressing handswitch 9.

A facility exists for including or eliminating ?-prints from the translated programme depending on the setting of handswitch 4 during the translation process. This enables one to proceed at once to "production" by eliminating the "development" printing without having to reperforate the tape.

Detailed operating instructions are given below:

I To input the AUTOCODE LIBRARY TAPE by TELEINPUT

1. All block-isolation switches DOWN (except 7 on DRUM 1)
2. Autocode Library tape in the reader.
3. Key 2 (ONLY) of bottom row of handswitches UP.
4. ITB.
5. Switch on to CONTINUOUS.
6. The tape is read in. terminating with a continuous hoot.
7. Switch off to SINGLE.
8. ISOLATE switches 0 and 3 on DRUM 0.

IF MATRIX OPERATIONS USED

1. Put switch 7 on DRUM 1 DOWN.
2. MATRIX TAPE in reader.
3. Proceed as above to Switch off to SINGLE.
4. ISOLATE switch 7 on DRUM 1.

II To input an AUTOCODE PROGRAMME TAPE

This is the usual procedure when putting a fresh programme into the machine, and has the effect of resetting all the stores to a standard state. This is essential should it prove necessary to repeat the run for a consistency test.

1. Programme tape in reader.
2. Set the bottom row of handswitches:
   1. ALL ZERO - normal input.
   2. KEY 4 (ONLY) UP - if query printing 1s required.
   3. ITB.
   4. Switch on to CONTINUOUS.

Ihe programme 1s now translated and entered on reading a starting chapter 0.

IlIA. Faults encountered during INPUT

1. The machine may come to a 99 stop (PF = all zeros). CAUSE: NO matrix tape in machine OR incorrect form of instruction.
2. The machine may stop and record ACCUMULATOR OVERFLow (the 2 most significant digits of YA are different), CAUSE: Incorrect form of instruction.
3. The parity light may come ON with PF = 0010100 but NO drum selection light ON. CAUSE: Incorrect form of instruction OR ERROR on tape.
4. The machine may come to a LOOP STOP (PF = 0000001000) IN THIS CASE, LOOK IN B7 which will give the FAULT NUMBER (see Appendix 1).

>Certain versions of AUTOCODE do not stop on encountering an input fault, but continue to translate and list all the faults discovered during the input attempt.

IIIB. Faults encountered during OPERATION

1. The machine may come to a loop stop (as Note 4 in IIIA). LOOK IN B7 for FAULT NUMBERS 8, 32, 33 to 35. Fault 32 can be surmounted after correcting the tape, by resetting control to 15.0.
2. The machine may record ACCUMULATOR OVERFLOW. i.e. The numbers have exceeded capacity, > 10⁷⁷.

IV. Action required when the hooter sounds

1. HALT: medium intermittent hoot. Depress KEY 9 to surmount.
2. HOOT: one single hoot. No action necessary.
3. END: continuous hoot. Final and insurmountable.
4. The warning sequence ® CR LF (normally at end of tape): Slow intermittent hoot - calling for more programme. Fast intermittent hoot - calling for more DATA. Depress KEY 9 to surmount in both cases.

V. Methods of RESTARTING

1. To re-enter the current chapter 0
   1. Put up KEYs 9 and 1 ONLY (of the bottom row of handswitches).
   2. ITB.
   3. Switch on.
   The current chapter 0 will be re-entered at the first instruction.
2. To read in a new chapter 0 (or an entirely new programme) from tape. In this case the number stores are not reset to a standard state, and the modified (or new) programme will find them in the state in which they were left by the previous calculation.
   1. Put up KEY 0 ONLY (of the bottom row of handswitches).
   2. ITB.
   3. Switch on.
   The machine will read in the tape. N.B. In both cases the INDICES are destroyed.

To preserve the indices do NOT press I.T.B. as in (b), instead CLEAR CONTROL as follows:

• b1) Set MAN/AUTO switch to MAN,
• b2) Put KEY 3 up on TOP row of handswitches,
• b3) Clear MIDDLE row of handswitches.
• b4) Press PREPULSE button,
• b5) Return MAN/AUTO switch to AUTO.