U UNIVAC 1218 - Bitsavers

CHANGE 2
Code
3
4
5
I - Bits 3, 2.
functions. 10
Reason
A punch check has occurred and recovery has failed.
An illegal function code received by the slave.
No initiation sequence performed to initiate the
master/slave interface.
Interpretation code. 01: Termination of output
Hardware or software error
C - Bits 1, O. Always 11 identifying the external interrupt command.
2.5 INITIATION SEQUENCE
Prior to the execution of any data transfers or control functions, the
master computer must perform an initiation sequence (handshake).
The handshake is performed as follows.
1) Send MEFW with control field, (bits 1, 0), set to zero.
2) Receive external interrupt from slave. The command byte of the
accompanying EISW will have a S field of 0, I field of 01 and a
C code of 11.
2.6 DATA TRANSFER SEQUENCES
All data transfers sequences shall originate in the master computer. The
interface for output, input, and special functions is defined below.
2.6.1 OUTPUT DATA TRANSFER
Any data sent to the slave for output must be preceded by a message header.
The message header may be sent to the slave without any accompanying data to
set up the slave handler for a specific format and the subsequent use of the
special function. Multiple card images may be sent depending on the memory
size of the slave. The output 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
message header plus the word length of the output data buffer plus
one word (length in 18, 30, or 36 bit 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) Accept an external interrupt and accompanying EISW signaling completion
of the output function (device end interrupt).
II-G-14