U UNIVAC 1218 - Bitsavers
U UNIVAC 1218 - Bitsavers
U UNIVAC 1218 - Bitsavers
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CHANGE 2<br />
Code<br />
3<br />
4<br />
5<br />
I - Bits 3, 2.<br />
functions. 10<br />
Reason<br />
A punch check has occurred and recovery has failed.<br />
An illegal function code received by the slave.<br />
No initiation sequence performed to initiate the<br />
master/slave interface.<br />
Interpretation code. 01: Termination of output<br />
Hardware or software error<br />
C - Bits 1, O. Always 11 identifying the external interrupt command.<br />
2.5 INITIATION SEQUENCE<br />
Prior to the execution of any data transfers or control functions, the<br />
master computer must perform an initiation sequence (handshake).<br />
The handshake is performed as follows.<br />
1) Send MEFW with control field, (bits 1, 0), set to zero.<br />
2) Receive external interrupt from slave. The command byte of the<br />
accompanying EISW will have a S field of 0, I field of 01 and a<br />
C code of 11.<br />
2.6 DATA TRANSFER SEQUENCES<br />
All data transfers sequences shall originate in the master computer. The<br />
interface for output, input, and special functions is defined below.<br />
2.6.1 OUTPUT DATA TRANSFER<br />
Any data sent to the slave for output must be preceded by a message header.<br />
The message header may be sent to the slave without any accompanying data to<br />
set up the slave handler for a specific format and the subsequent use of the<br />
special function. Multiple card images may be sent depending on the memory<br />
size of the slave. The output data transfer sequence is!<br />
1) Send the MEFW to the ICCU via an external function command.<br />
2) Initiate an output buffer with a length equal to the word length of<br />
message header plus the word length of the output data buffer plus<br />
one word (length in 18, 30, or 36 bit words, not bytes).<br />
3) Accept an external interrupt and accompanying EISW upon completion of<br />
data transfer (channel end interrupt). The command byte of the EISW<br />
will be zero upon termination of data transfer.<br />
4) Accept an external interrupt and accompanying EISW signaling completion<br />
of the output function (device end interrupt).<br />
II-G-14