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When considering the options to be connected to the DATANET-30, the number of memory cycles
to be used must also be considered.
Since only 5 cycles are available for assignment, the
options using the interrupt interface cannot exceed 5. However, this will not normally be a prob-
lem because of the types of options that use the interrupt cycles.
Allocation of Cycles
Allocation of cycles is based on requirements for frequency of memory interrupts.
The
DATANET-30 has a maximum total throughput limit of 144,000 18-bit words per second. Since
DATANET-30 cycles will be designated in groups of 5 cycles, each device on interrupt utilizing
one of the cycles can have a word input/ output frequency no greater than one-fifth of the maximum
throughput, or 28,800 words per second.
Generally, devices with transfer rates less than 28,800 words per second will be allocated a
single cycle of the group of 5 cycles. Devices with transfer rates higher than 28,800 words per
second will be allocated correspondingly more than one cycle out of 5 cycles in a group.
The CSU (Controller Selector Unit), for example, has a maximum transfer rate of 57,600 words
per second.
It
will, therefore, be allocated 2 cycles out of the group of 5. In addition, the CSU
is allocated a definite 2 cycles out of the 5; namely, cycles 1 and 3.
Some devices may be assigned definite cycles within the group while others may be required to
have the cycle(s) plug selectable.
In some instances, more than one mechanism requiring data
interrupts may be assigned the same interrupt cycle. In this case, the device interrupt module
receives the burden of allocating subpriorities to the mechanisms.
The DATANET-30 interrupt scheme is so designed that all 5 cycles of every group can be used
for data interrupts.
Even though subpriorities may be assigned to multiple mechanisms on a
single interrupt cycle, all devices on data interrupt will be guaranteed their assigned cycles
since no cycle will be assigned to more than one device. When multiple mechanisms are used,
it can be assumed that these multiple mechanisms make up a single device.
CONTROL CONSOLE
The control console is designed to serve both operator and maintenance functions. The operator
functions are at a minimum, however.
The DATANET-30 is designed to operate without direct
operator control via the control panel. Once the program is running, most control functions will
be initiated from the supervisory position keyboard/printer.
The control panel provides means for the supervisor to start the program and check that the
operate/maintenance, count P, count
Q,
Halt, mode select and buzzer switches are all in the
correct position.
The start-up sequence is:
power on, check all the above switches and press
the manual load button.
This enters the program from the paper tape reader. When the paper
tape reader stops, the program is running and all other control functions will be initiated from
the supervisory position.
The other buttons and switches are not normally used by the supervisor. They are for mainte-
nance, trouble shooting and program debugging purposes.
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