IOEL (input/output extended logout) (continued)
control register bit 182
pointer 240 IPL (initial program load) 54 IPL CCW1 , CCW2, in absolute main storage :91 IPL PSW in absolute main storage 91
key in storage error uncorrected bit (machine-check interruption
code) 180 key, protection, in CSW 228,236
key, storage 38
accesses 24
length of operand 19
immediate operands 20 register operands 20 storage operands 20 limited channel logout 240 detect field 240 field validity flags 241
in main storage 91 I/O address 242 I/O error alert 241
sequence code 241
source field 240 storage control unit (SCU) identity 240 type of termination 241
load
indicator 245
key 245
state 31
unit-address controls 246 LOAD (LDR, LD, LER, LE) instruction 165 LOAD (LR, L) instruction 1.30 example 298 LOAD ADDRESS (LA) instruction 131
example 299 LOAD AND TEST (LTDR, LTER) instruction 165 LOAD AND TEST (LTR) instruction 131 LOAD COMPLEMENT (LCDR, LCER) instruction 165 LOAD COMPLEMENT (LCR) instruction 131 LOAD CONTROL (LCTL), instruction 105 LOAD HALFWORD (LH) instruction 131
example 299 LOAD MULTIPLE (LM) instruction 132 LOAD NEGATIVE (LNDR, LNER) instruction 166 LOAD NEGATIVE (LNR) instruction 132 LOAD POSITIVE (LPDR, LPER) instruction 166 LOAD POSITIVE (LPR) instruction 132 LOAD PSW (LPSW) instruction 105 LOAD REAL ADDRESS (LRA) instruction 106 LOAD ROUNDED (LRDR, LRER) instruction 166
loading of initial program information 54
logical storage
address 14,58
address translation 58
addressing 58
logout
asynchronous/synchronous 177
extended/fixed 177
main storage, permanently· assigned locations 92
pending (LOP), in CSW 228
(see also machine-check extended logout and machine-check
fixed logout)
logout control 181 Page of GA22-7000-4 Revised September 1. 1975
By TNL: GN22-0498
long block (in I/O) 233
long floating-point number 158
machine-check
code 75, 178
detection 171
handling 172
machine-check control register
bits (chart) 183
subclass masks 182
subclass masks summary 183
machine-check extended interruption information 177
register save area 178
machine-check extended logout (MCEL)
address in control register 181
asynchronous, control of 182
asynchronous, definition 177
control, summary chart 183
length in machine-check interruption code 181
maximum length, in CPU ID 112
synchronous, control of 181
synchronous, definition 177
valid bit (machine-check interruption code) 180 machine-check fixed logout
area 177
asynchronous, control of 182
asynchronous, definition 177
control, summary chart 183
synchronous, definition 177
machine-check interruption 75
action 175
code 178
code in main storage 91
code validity bits 180 mask, BC mode 34
mask, EC mode 35
point of 176
machine-check logout, synchronous/asynchronous 177
control (chart) 183
extended (see machine-check extended logout)
fixed (see machine-check fixed logout)
machine-check mask
BC mode 34
EC mode 35
subclass masks 183
summary chart 183
machine-check save areas (machine-check extended interruption
information) 177
machine errors, handling of 172
main storage
accesses, sequence of 23
actual operation 23
conceptual operation 23
address wraparound 14
addressing 14
assigned locations 90 absolute 91
real 90 controlled sharing of by TEST and SET 144
controlled sharing of by COMPARE AND SWAP 123
general description 14
integral boundaries 15
power-on reset effect 53
reference and change recording 67
volatile 14
Index 321

Page of GA22-70004 Revised September 1, 1975
By TNL: GN22-0498
malfunction-alert external interruption 86,175
malfunction (selective) reset in I/O system 195 indicator 246
manual operation of system (see system console)
mask (in BC mode PSW) channel 33 33 I/O 33
maGhine-check 34
program 34
masks (in EC mode PSW) external 34
inplllt/output 34 maGhine check 35
program 35
program-event recording 34
mask bit in control of interruptions 71
mask position values used in BRANCH ON CONDITION 121
masks, monitor 39
MCEL (see machine-check extended logout)
microprogram controls, initial 245
mode
BC (basic control) 32
control bit in PSW 34
EC (extended control) 32 \
of channel operation (data transfer) 188
modifier bits in CCW command code 212 MONITOR CALL (MC) instruction 132
monitoring 39
class number 39,91
code 39,91
inte:rruption identification (see monitor class number;
monitor code) 91 masks (in control register 8) 39 MOVE (MVC, MVI) instruction 133
example 299 MOVE LONG (MVCL) instruction 133 MOVE NUMERICS (MVN) instruction 135
example 300 MOVE WITH OFFSET (MVO) instruction 135
example 300 MOVE ZONES (MVZ) instruction 136
example 300 multiple PCI interruptions (see programming notes) 221 multiple simultaneous interruption requests (see priority of
interruptions) 89
multipllexer channel (see byte-multiplexer channel and
block-multiplexer channel)
MULTllPLY (MDR, MD, MER, ME) instruction 167
MULTllPL Y (MR, M) instruction 136
example 301 MULT1[PL Y (MXD, MXDR) instruction 167 MULTIPLY (MXR) instruction 167 MULTIPLY DECIMAL (MP) instruction 153
example 307 MULTIPLY HALFWORD (MH) instruction 136
example 301 multiprocessing 95, 9
exam pIes 310 near valid CBC 171
no-ope:ration control command 219
non shared subchannel 189
nonvolatile main storage 14
normal sequential instruction execution 22
normalization in floating-point arithmetic 159
322 System/370 Principles of Operation
not operational (state of I/O system) 192
not ready status bit 100 nullification (method of ending instruction execution) 74
number representation
decimal 148
fixed-point 116
with two's complement 289
floating-point 159
numbering
bits of a byte 14
byte locations in main storage 14
numerics 147
one's complement, use of in fiJted-point operations 117
op code (operation code) 20 operand field length 14
operands
address specification of 19
immediate 20 in main storage 20 in registers 20 storage 25
fetch reference 25
relation between references 27
store reference 25
update reference 26
operating state 30 operation code (of an instruction) 20 operation exception 76
operation, I/O 186, 17
operation, unit of 74
operational (I/O state) 192
operator-intervening status bit 99
operator section (of system control panel) 243 OR (OR, 0, 01, OC) instruction 137
example 301 order
conditions determining response to 98 I/O (definition) 189
signaling and response 97
order-code interpretation, conditions precluding 98
organization, system 13
overflow
decimal 147
exponent 158
fixed-point (see ADD (AR» 117
overlap, destructive (in MOVE LONG) 133
overlapped fields, decimal 147
overrun (sense data) 220 PACK (PACK) instruction 137
example 302 packed decimal number 147
page 58
address 60 index field 58
invalid bit 60 size bits (in control register 0) 58
table 60 address 60 entries 60 entry format 60 length 60 lookup 61
page-translation exception 79
parity bit 171