Bootstrap Button - Honeywell 200 Series Hardware Manual

SECTION II. OPERATOR'S CONTROL PANEL
The INSTRUCT button is effective only when the system is in the STOP mode with the
PARITY and PROGRAM indicators extinguished. Pressing this button causes the program to
execute only the next instruction. While that instruction is being executed, the STOP indicator
is turned off, and the RUN indicator is illuminated.
If the instruction specifies a peripheral
data transfer, the RUN indicator is turned off when the data transfer begins, so that both the
RUN and STOP indicators are turned off until data transfer terminates. At the completion of
the transfer, the STOP indicator is illuminated.
If the central processor is not in the interrupt mode but is storing an interrupt demand,
pressing the INSTRUCT button on the control panel causes the interrupt mode to be entered.
When depression of the INSTRUCT button causes the interrupt mode to change, no program
instructions are executed.
BOOTSTRAP Button
..
The BOOTSTRAP button is effective only when the system is in the STOP mode. When it
is depressed, the following conditions result:
1. The address indicated by the setting of the ADDRESS buttons is placed
into the sequence register, the A- and B-address registers, and both
the starting and current location counters of read/write channel one;
2. A simulated peripheral read or write instruction specifying read/write
channel one is generated. The peripheral control addressed is des-
ignated by the setting of the low-order six bits of the CONTENTS push-
buttons (memory local register).
If a tape control is designated by
the memory local register bits, tape driv.e number zero is read.
NOTE: A write instruction is issued if the CONTENTS buttons desig-
nate the address of. a printer control or a card punch control;
if they designate the address of a tape control, the generated
peripheral instruction is always a read.
3. The punctuation bits of each character read into memory during a BOOTSTRAP
operation are automatically cleared to zeros. A BOOTSTRAP operation is
not terminated by a record mark in memory.
4. The information flow is terminated by the peripheral control.
NOTE: In the Type 224-1,2 Card Reader/Punch, data transfer is
terminated only by a record mark in memory.
The contents of the memory address register, the memory local register, the sequence
register, the A- and B -address registers, and both the starting and current location counters
of read/write channel one are altered by the BOOTSTRAP operation. The setting of the ADDRESS
MODE buttons at the time the BOOTSTRAP button is pressed has no effect on the BOOTSTRAP
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