IBM System/370 145 Reference Summary page 24

BRANCH SYMBOLS
0 Insert 0
Insert 1
BO-B7 Insert value of specified bit
BH Insert 1 if branch source bits 0-3
=I=
0
BL Insert 1 if branch source bits 4-7 =I= 0
10 Force return I-cycles
11 Force return I-cycles if no interrupt
M6 Insert M6 value after address update
M7 Insert M7 value after address update
NZ Insert 1 if branch source bits 0-7 =I= 0
SO-S7
iZO
TH
AB
Insert value of specified S-register bit
Insert 1 if S4 and S5
=
1
Special - M3 bits 2 and 3 replaced by
T-register bits 0 and 1, then module
switch
If TA or TB is decrementing, branch
when 00. If TA or TB is incrementing,
branch when 11
STAT SET SYMBOLS
S2 Storage word - S2 set to 1 if count
=F
0, otherwise S2 set to 0
S12 S1 - binary byte OPS: S1 set to 1 if
carry out of bit 1 of result. Binary
fullword OPS: S1 set to 1 if carry out
of byte 0, bit 1. Decimal ops: S1 set
to 1 if an invalid decimal digit detected.
S2 - Set to 1 if result
=I=
0
S45 Arith ops:
Z6
Z24
124
S4
=
1 if bits 0-3 of Z-bus
=
0
S5
=
1 if bits 4-7 of Z-bus
=
0
Storage word ops: Same except test
made on low byte of count field after
update
Same as S45 stat set except S4 depends
on bits 0-5
Arith fullword OPS: If the low 24 bits
of result
=I=
0, S2 set to 1, otherwise S2
unchanged. S3 set to 1 if carry out of
bit 0, byte 1. Only low 24 bits of re-
sult gated to destination
Arith ops: Inhibits set of any S-reg_
bits. Only low 24 bits of result gated
to destination. In shift operations, the
high four bits of result set to 0 regard-
less of shift type
ALU ENTRY GATING
A-Reg
0
High
3
4
Low
7
i::;:---------
...
......
,,,,.,
...
';.-<:
A-Entry Gating
BS Straight
BSO Block High and Low
BSH Gate High; Block Low
BSL Gate Low; Block High
BSX Cross High and Low
ALU
0
3
4
7
BSXH Cross; Gate High; Block Low
BSXL Cross; Gate Low; Block High
8-Reg ALU
0
High
3
4
Low
7
B- Entry Gating
BS Straight
BSO Block High and Low
BSH Gate High; Block Low
BSL Gate Low; Block High
1.15
0
3
4
7
D