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2.1.2.3 CE Mode Selector
This rotary switch selects one of three processor operating
modes: the nonnal process mode, the step mode, or the
test mode. Process is the mode for normal programmed
system operation.
In the step mode, the rotary switch setting controls the
manner in which the processor executes the stored program.
There are three positions in the step mode.
Note:
If this switch is changed while the system is running,
a processor check can occur.
Instruction Step: In the instruction step, each start key
depression and release causes one complete instruction to
be executed. The I-phase is performed while the key is
pressed and the E-phase, if any, when the key is released.
Note: Any SIO instruction which causes the clock to run
as described under Qock Step also causes the next sequen-
tial instruction to be executed without start key operation.
File
P1
P2
Write
BSCA
Off
Off
Off
On
i
~
CtY
~
Off
On
On
On
Local
Test
1/0
Parity
Storage
Addr
Addr
1/0
Check
Check
Test
lncrem Compare Overlap
Stop
Run
Run
Off
Stop
Off
ctp~
~ ~
~qy
Run
Stop
Step
On
Run
On
Page of SY31-0244-2
Revised December l, 1971
By
TNL: SN31-0307
Machine Cycle Step: In the machine cycle step, each start
key depression and release advances the instruction through
one machine cycle. Pressing this key causes data in storage
to be accessed, modified as required, and the results dis-
played in the arithmetic logical unit (ALU) indicators of the
console display. Upon release of the key, depending on the
operation being performed, either the old data or the new
result is written back into storage.
Qock Step: In the clock step, pressing the start key causes
the clock to advance through and odd-numbered clock.
Releasing the key causes the clock to advance through an
even-numbered one.
The integrity of 1/0 data transfers is preserved by allowing
the clock to run from the I-phase end of every executable
start I/O instruction to the time the device is finished trans-
ferring data. The start key is not functional while this I/O
transfer is taking place.
In systems without dual program feature, the halt identifier
lights do not turn on in any step mode.
There are also three positions of the switch under test
mode: alter SAR, alter storage, and display storage.
Address
1/0
CE
Compare
Check
Key
11111-1@
@
CD
'
(CE USE METER)
Normal
Display
T
Stor
\
r
Instr
I
System
]
[];]
~
ARR
XR2
I A R U - X R 1
~T~
Proc~
St~~
Stor
Cycle
Alter_~_
Machine
Reset
t
OFF -
-
OFF
Alter_
_Cl
k
p
SAR
oc
LSR Display
Selector
CE Mode Selector
Figure 2-5. CE Control Panel
5410MM
2-5
E
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