Execution Times - Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual

TABLE 4-1. DEVICE INPUTS AND OUTPUTS
DEVICE
Memory
Keyboard
PLATO communication interface
Serial channel
Maintenance LEDs
Switches
Identification code setting
Touchpanel
Parallel channel
Interrupt mask
MICROPROCESSOR
INPUT/OUTPUT
Both
Input
Both
Both
Output
Input
Input
Input
Both
Output
The following paragraphs discuss the execution times, PLATO
communications interface, serial channel interface, paral-
lel channel interface, terminal identification, and
programming.
Execution Times
The state time is fixed at 250 nanoseconds. The program
memory addresses 0000 16 through 7FFF16 are dedicated
exclusively for program storage. The controller is the
only user of this memory. The refresh memory addresses
8000 1 6 through FFFF16 contain the information to be
displayed on the screen, and both the display logic (read)
and the controller (read/write) have access to this memory,
with the display having top priority. The fact that what-
ever information stored in the refresh memory is displayed
on the screen does not preclude the possibility for storing
and executing programs in it.
The following rules must be followed when calculating exe-
cution times:
• Add one state time (WAIT state) to each instruction
(whether it is a 1-, 2-, 3-, or 4-byte instruction)
if it is stored in the program memory.
82100083 B
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