U UNIVAC 1218 - Bitsavers

2.6.2 INPUT DATA TRANSFER
CHANGE 2
To input data, a message header is sent to the slave to request input of
data or to set up the slave handler for a specific input format and the
subsequent use of the special function. Multiple cards may be read depending
on the memory size of the slave. The input data transfer sequence is;
1) Send the MEFW to the ICCU via an external function command.
2) Initiate an output buffer with a length equal to the word length of
the message header plus one word (number of words not bytes).
3) Accept an external interrupt and accompanying EISW upon completion of
data transfer (channel end interrupt). The command byte of the EISW will
be zero upon termination of data transfer.
4) Initiate an input buffer with a length equal to the number of words
being sent multiplied by the number of characters per word plus one.
5) Send the MEFW to the ICCU via an external function command.
6) Accept input data and upon completion of data transfer accept an
external interrupt and EISW (device end interrupt). The command byte of
the EISW will be zero.
Due to the timing characteristics of the slave handler and the ICCU, the
master should issue the MEFW for input immediately upon receipt of the
first interrupt.
2.6.3 SPECIAL FUNCTIONS
For convenience in performing I/O operations, special functions are provided
as specified in the last message header sent to each device. The handshake
sequence sets up the slave handler to perform as follows.
1) Read one card (80 column), translate to XS-3
2) Punch one card (80 column), translate from XS-3
3) Print one line (120 characters), translate from XS-3
If an I/O function is to be performed other than specified above, a message
header must be sent for that device to reset the slave handler to perform in
the manner desired.
A special function code must be given in the D field of the MEFW in place of
the byte count to use the special function.
II-G-15