Integrated Register File; Real-Time Clock; Move Operation - Control Data 3100 Reference Manual

Program requests are produced as the direct result of a programmed instruction. An
instruction of this type may perform the following:
1.
Initiate the processing of a block of data,
2.
Terminate the processing of a block of data,
3.
Direct inter-register transfers in conjunction with the Register File,
4.
Transmit Connect or Function commands to I/O channels.
Any request to Block Control, except for Connect or Function, results in one or more
Register File references. Block operation requests process blocks of data as directed by
the initial instruction.
Priority access is established for all Block Control operations with one exception: pro-
gram requests have either first or last priority. Last priority is granted only if a channel
request occurs almost simultaneously with the program request. The order of priority,
with program request listed first, is as follows:
1.
Program request.
2.
Channel 0 request.
3.
Channel 1 request.
4.
Channel 2 request.
5.
Channel 3 request.
6.
Real-time clock request.
7.
Typewriter request or Read-Store or Write-Store with Register File request.
8.
Search or Move request.
Every Block Control cycle normally completes the operation specified by the request.
A Move operation is the only possible exception. Due to the length of time required for
the Move operation cycle, it may be terminated in the middle of its cycle by a Channel
request. The aborted Move operation cycle results in no loss of data. The 'next complete
Move operation cycle moves the word or character of the aborted cycle.
INTEGRATED REGISTER FILE
The Integrated Register File is a 6410 word (24 bits per word) memory integrated into
the upper 64 addresses of storage. Although the programmer has access to all registers
in the file with the 53 instruction, certain registers are reserved for specific purposes
(see Table 1-3). All reserved registers may be used for temporary storage if their use
will not disrupt other operations that are in progress. The contents of any register in
the file may be examined by transferring them to the A register. Register 77 corresponds
to the uppermost storage address.
REAL-TIME CLOCK
The real-time clock is a 24-bit counter that is incremented each millisecond to a maxi-
mum period of 16,777,216* milliseconds. After reaching its maximum count, the clock
returns to zero and the cycle is repeated continuously. The clock, which is controlled
by a 1 kilocycle signal, starts as soon as power is applied to the computer. The current
time is stored in register 22 of the Register File. It is removed from storage, updated,
and compared with the contents of register 32 once each millisecond. When the clock
time equals the time specified by the clock mask, an interrupt is set. When necessary,
the real-time clock may be reset to any 24-bit quantity including zero by loading A and
then transferring (A) into register 22.
*16,777 ,216 milliseconds equals approximately 4 hours and 40 minutes.
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