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1.01, 1440, AND 1460 COMPATIBILITY
FEATURES
•
The
Syste~/360
is in compatibility
mode when W3 of the WX Reg is on.
•
Only one compatibility feature can
be present on the machine.
•
Any system reset causes the 2030 to
leave 1401 mode.
•
IJ, LT and UV perform the functions
of I-Star, A-Star,and B-Star, res-
pectively.
•
Sense switch settings for 1401
object program are stored in R8,
local storage.
The 1401, 1440, and 1460 Compatibility
Features are special features available
to the customer to allow him to run 1400
system (1401, 1440, 1460) object pro-
grams.
The facilitate the processing of
1400 system programs, a second 4R ROS
has been added to the 2030.
This addi-
tional ROS contains the micro program-
ming necessary to process 1400 system
instructions.
The 2030 can be put into
compatibility mode by turning on the W3
bit of the W-register.
This bit causes
the added 4R ROS to be addressed, and
controls all mode dependent functions.
Hardware is provided to allow W3 to be
sent from:
1.
the console switches
2.
the micro-program cont.rol UV->WX
3.
the micro-program control CA->WW.
When W3 is set from the console
switches, the position of rotary switch
F determines W3 (ie: F at an odd hex
digit will turn on W3).
The status of
U3 determines W3 when the micro-program
statement UV->WX is used to turn on
compatibility mode.
When the micro-
program program statement CA->W is used,
the status of AA determines the status
of W3.
Any system reset turns off W3
and causes the 2030 to leave
compatibility mode.
Recycle reset, the
micro-program control R->W, and priority
trapping, do not affect the setting of
W3 when the compatibility feature is
present on the machine.
SECTION 5.
SPECIAL
FE~TURES
When operating in compatibility mode,
IJ performs the functions of the I-star,
and UV performs the functions of B-star.
Hardware is provided so that the Land T
registers may be gated as a pair into
the MN-register when the T-register is
named as the source (ie: T->N LS causes
the address contained in LT to gate to
MN).
LT performs the fUnctions of the
A-star in compatibility mode.
To run 1401, ,.40 or 1460 object
programs on the 2030, an initiali2ing
program is loaded ahead of the object
program.
The purpose of the initializ-
ing program is to load the conversion
tables and address constants necessary
to perform 1401, 1440, or 1460 instruc-
tions into the
~PX
1 and local storage
areas of main storage.
The initializing
deck also defines by meanS of control
cards, the characteristics of the 1400
system being simulated (ie: memory size,
special features, and the I/O configu-
ration.)
IBM 1400 system sense switches are
set local storage by use of switch F on
the console.
The procedure is : set
switch F to the alpha-character designa-
tion of tpe sense switch desired, press
the interrupt key; press the start but-
ton.
The sense switch has now been set.
To turn off, the same procedure is used,
except switch F should be dialed 180
degrees opposite the alpha character
deSignation of the sense switch that you
wish to turn off (ie, switch F to C
turns on sense switch C, switch F to C
(4) turns off sense switch C.)
At
t~e
oomp1etion of altering sense switches,
the R-register displays 01110111, and
the A-register displays the whole sense
switch byte, (KS local storage) to indi-
cate the status of the sense switches.
After altering the desired sense
switches, pressing the start key causes
the processor to continue.
For additional
info~ation
on console
operation, read the SRL publication,
System/360 Model 30 1401 Compatibility
Feature,Form A24-3255.
The topic
·Operating Considerations· covers the
complete console operation for the Com-
patibility mode.
5-1
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