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System!370 Model 168 (cont'd)
To Alter (Store into) Main Storage
Every store operation should be preceded by a display operation to prevent destruction
of data by doubleword storing. For real addresses, use "Display Main Storage" pro-
cedure; for logical addresses, use "Translate Address and Display Main Storage" pro-
cedure shown after this procedure.
1.
Perform steps 1 through 7 of "Display Main Storage" or "Translate Address
and Display Main Storage."
2.
Set MANUAL ENTRY SELECT to MCDR.
3.
Press cursor advance key
=>
until the cursor underscores the byte in MCDR
where the data is to be entered.
4.
Enter the data change by pressing the data keys. As soon as the byte is
entered in the MCER, it is transferred to the MCDR where it can be check·
ed for accuracy. If an error occurs, press the cursor advance key until
wraparound occurs, and return to the byte desired. Enter the correct data.
Translate Address and Display Main Storage
The CRT displays eight bytes, starting with the logical location addressed.
1.
Press STOP. Manual light turns on.
2.
Set CRT MODE SELECT to CEo
3.
Set STORAGE SELECT to MAIN STOR.
4.
Set MANUAL ENTRY SELECT to MCAR to enter the logical (virtual)
address.
5.
Press the cursor advance
k~y
=>
until the cursor underscores the second byte
in MCAR. (The first byte is ignored.)
6.
Enter a six-hex-digit logical address by pressing the data keys. As each key is
pressed, the appropriate digit appears in the MCER. As every second digit
completes a byte, that byte appears in the MCAR and the cursor advances to
the next byte.
7.
Press TSLT ADR
&
DISPLAY MAIN. The real address replaces the logical
address in MCAR, and the data at the real address appears in MCDR. If
Zeros appear in ooth
th~
MCAR and MCDR, t:'ilhel
r.i
ban:;ldliofi t:}('l:eJ-lliulI
associated with the specified logical address has occurred, or the resulting real
address is invalid for the system.
8.
Restore CRT MODE SELECT to OP.
9.
Press START to resume processing.
To Stop
on
Main Storage Address
1.
Press STOP. Manual light turns on.
2.
Set STORAGE SELECT to MAIN STOR.
3.
Set ADDRESS COMPARE/SYNC: to IC for a match between the IC and the
logical address set in the MRAR; or
to CHAN for a match between a real address set in the MRAR and a main
storage address selected by a channel; or
to CPU/CHAN for a match between a real address set in the MRAR and an
address selected either by the CPU or by the channels; or
to CPU (REAL) for a match between the address selected by the CPU and
the real address set in the MRAR; or
to CPU (LOGICAL) which is the same as "Real Address" except that
3
logical address must be entered in the MRAR.
4.
Set CS/MS to MS; set stop
on
oompare (MS) to STOP.
5.
Set CRT MODE SELECT to CEo
6.
Set MANUAL ENTRY SELECT to MRAR.
7.
Press cursor advance key
=>
until the cursor underscores the second byte in
MRAR displayed on the CRT. (Using a six-byte address, ignore the first
MRAR byte.)
8.
Enter six-hex-digit logical address (where stop is desired) by pressing the data
keys. As each key is pressed, the appropriate digit appears in the MCE R. As
f?,/ery second digit completes a byte, that byte appears in the MRAR and the
cursor advances to the next byte. If an error occurs, press the cursor advance
key until wraparound occurs, and return to tpe byte desired, then enter [he
correct digits.
9.
Return CRT MODE SELECT to OP.
10.
Press START to resume processing.
11.
When the CPU stops at the desired compare stop, reset CS/MS to CS/MS,
reset stop on compare (MS) to NORM, and press START to resume pro-
cessing.
Page 3-20
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