Page of GA22-7000-4
Revised September 1, 1975
By TNL: GN22-0498
busy (I/O unit status condition) 230, 238
byte (definition) 14
byte index field 58
byte-interleave mode 187
byte-multiplexer channel 188
byte-oriented-operand feature 15
cache 13
CAl (channel available interruption) 227
CAW (channel address word) 210,190
CBC (checking block code) 171
CBC, invalid
handling of
in keys in storage 173
in registers 173
in storage 172
CCW (channel command word) 189,211
address in CAW 210 address in CSW 229
command code 212
definition 211
CCWI (lPL) in absolute main storage 91
CCW2 (lPL) in absolute main storage 91
central processing unit (see CPU) chain command (CC) flag (in CCW) 211
chain data (CD) flag (in CCW) 211
chaining check (channel status condition) 235,237
chaining, command 215,279
chaining data 213,191
change bit 57,67 channel 187
address 192
burst mode 187
byte-interleave mode 187
commands 217
compatibility of operation 191
control check (status condition) 235,237
data check (status condition) 235,237
description of 17
equipment error 196
identification (lD) 240,206
indirect data addressing (CIDA) 216
mask, BC mode (see extended control mode) 33
masks (in control register 2) 88
modes of operation 187
not operational (state of I/O system) 194
program, termination of (or conclusion of) 222
sub channel 188 types 188
working (state of I/O system) 194
channel address validity flag 241
channel address word (CAW) 190,210
channel available interruption (CAl) 227
channel command word (see CCW)
channel end (I/O unit status condition) 231, 238 channcllD 240,92,206
channel logout 240 channel status conditions 233 chaining check 235
channel control check 235
channel data check 235
incorrect length 233
interface control check 235
program check 234
program-controlled interruption 233
protection check 234
316 System/370 Principles of Operation
channel status word (CSW) 228
channel-to-channel adapter 186
characteristic in floating-point operand 158
check (or checking) bit 171, 14
check-stop indication 245
control bit (in control register 14) 181
status bit 99
check-stop state 31
checking block 171
code (see CBC)
class number, monitor 39
classes of interruptions (see interruption classes)
CLEAR I/O (CLRIO) instruction 198
clock
interval timer as a real-time 49
time-of-day (TOD) 46
clock comparator 47
interruption 48, 87
interruption submask 88
mask bit (in control register 0) 87
priority of interruption 86
valid bit in machine-check interruption code 180 save area (machine-check extended interruption information,
timing facilities) (see timing facilities) 177
code
command 217
condition (see condition code in PSW) instruction length 71, 34, 72
interruption, in BC mode PSW 34, 72
monitor 39
operation 19
PER (program-event recording) 40 codes, decimal sign, and zone 148
command
control 219 I/O 210,217
read 218
read backward 218
retry 221
sense 219
transfer in channel 221
write 218
command address, I/O 236
in CAW 210 in CSW 229,235
command address/key validity flag 241
command chaining 215,191
command code (in CCW) 211
command, immediate (see immediate operation) 222
command reject (sense data) 220 command retry 221
communications area, I/O 239
COMPARE (C, CR) instruction 123
COMPARE (CDR, CD, CER, CE) instruction 163
example 310 COMPARE AND SWAP (CS) instruction 123
example 310 COMPARE DECIMAL (CP) instruction 149
example 305 COMPARE DOUBLE AND SWAP (CDS) instruction 124
COMPARE HALFWORD (CH) instruction 125
example 294
COMPARE LOGICAL CHARACTERS UNDER MASK (CLM)
instruction 126
example 295

COMPARE LOGICAL (CLR, CL, CLI, CLC) instruction 125
example 294 COMPARE LOGICAL LONG (CLCL) instruction 126
example 295
compatibility and compatibility limitations in
System/370 2
compatibility of I/O operations 191
completion (method of ending instruction execu tion) 74
conceptual sequence (order) in instruction execution 23
concluding (termination of) I/O at operation initiation 222
by HALT I/O or HALT DEVICE 224
due to equipment malfunction 226
of data transfer 223
of I/O operations 222
concurrent within a block, storage references 25
condition code (CC)
deferred (DCC), in CSW 229
setting for I/O instructions 195
setting, summary of (see Appendix E)
condition code in PSW 22
BC mode 34
EC mode 34
program mask and condition code validity bit 180 conditions
determining response to orders 98
external interruption 84 I/O interruption 226, 88
precluding interpretation of an order code 98
program interruption 75
configuration controls 245
console device (of the system console) 243
console, system 243,18
control
check-stop 181
logout 181
panel, system 243
store status 54
system 29
control command, I/O 219
control panel, system 243
control register 36, 16
field and bit assignments 37
machine check controls 181,183
save area (machine-check extended interruption
information) 177
valid bit (machine-check interruption code) 181
control unit 187
address in device address 192
attachment in system 187
description of 18
functions 187
selection 192
control unit end (I/O unit status condition) 230 CONVERT TO BINARY (CVB) instruction 127
example 296
CONVERT TO DECIMAL (CVD) instruction 128
example 296
count 236
in CCW 211
in CSW 238
counter, instruction (see instruction address in PSW) coupled general registers 16 Page of GA22-7000-4 Revised September 1, 1975
By TNL: GN22-0498 CPU (central processing unit)
address iden tifica tion 101 general description 15
initialization reset 51
power-on reset 53
reset 50 reset order 98
retry 172
signaling and response 97 CPU states 30 problem/supervisor 30 stopped/ operating 30 wait/running 30 CPU timer 48
interruption 48, 88
interruption submask 88
mask bit (in control register 0) 88
priority of interruption 86.
save area (machine-check extended interruption
information timing facilities) (see timing facilities) 177
valid bit in ·machine-check interruption code 180 CSW (channel status word) 228
current PSW 16, 22
customer-engineer-control section (of the system control
panel) 248
D field of an instruction 20 damage condition 175
DAT (see dynamic address translation)
data
address (in CCW) 211
block, I/O (definition) 210 chaining (in I/O operations) 213,191
check (sense data) 220 exception 78
format
decimal instruction 147
fixed-point numbers 116
floating-point instruction 157
general instruction 116
formats 14
prefetching and buffering of in channel 212
transfer (I/O) concluding of 223
modes of 187
decimal
data format 147
divide exception 78
number representation 148
operands 147
overflow exception 78
packed 147
sign codes 147,148
zoned 147
decision making by BRANCH ON CONDITION instruction 22
deferred condition code (DCC) 229
degradation
machine-check interruption condition 179, 175
report mask bit 182
delayed bit, machine-check interruption code 180 deletion, unit 172
destructive overlap (in MOVE LONG) 133
detect field (in limited channel logout) 240 Index 317