IBM System/360 2050 Maintenance Manual page 168

BYTE COUNTER END REG
A
FULL READ
c
BKWD OP ROY IF OP ROY
Bit
Indicator ALO Position
Description
BYTE
H
GRl31
CTR GRl31 0-2 Byte counter phase A and parity.
A GR131
BYTE n GRl31
CTR GRl31 3-5 Byte counter phase Band parity.
B
GR131
END
u
GClll
6-7
The end register point. to the last byte plus one to be transferred.
REG GClll
LAST
n
GC141
WORDS GC141 8-10
The last word latches control the last three words in a read or write routine.
GC141
(7"""
GC151 II
Count interlock indicates when the channel has stored the fourth from the last word in a read
operation ar has fetched the last ward in a write operation.
EOR
GC151 12 End of record l indicates when the interface is using the last word latches.
GC151 13 End of record 2 indicates when the external channel controls are using the last word latches.
RD INTLK GC151 14 EOR read interlock indicates when the interface logic has finished using the last word latches
and is
r~uesti'!i_
the external channel control to take over.
BAC GG131 15
'8
r~ister
almost
~n!!!d'
indicates
~atJ:ocal
store
is~ing::§ifassed
in !fi:e data
tran~r
pa!fi:.
LS ENABL
GG13l
16
Local Store enable indkates
tn~t
data will be trao>sferred between luc"I store
and~
6 r·,,·i•kr.
{
LS GC171
17-19 Indicate when local store, the Bregister, or the C register contain data.
REG B GC171
FULL
c
GT141
I
BKWD GC131 20
· Read backward indicates a read backward op has been decoded.
READ
OP GC131 21
Read op indicates a read type op has been decoded.
ROY GF161
22
Read ready indicates that the channel is performing a read type op and is permitted to make
data store request..
IF GT121
23
Read interface indicates that the interface is now ready to read.
{
OP GC131 24 Write op indicates a write type op has been decoded.
WRITE ROY GF161 25 Write ready indicates that the channel is performing a write type op and is permitted to make data
fetch request..
IF
GT121 26 Write interface indicates that the interface is now rea<!J'.. to write.
CD=PC TYPE GElll
27 CD=PC type check indicates a program check during o write data chaining CCW fetch sequence.
SIM GGl31 28 Simulated check indicates that the channel wil I interrupt without the unit's status.
ILi GEi 11 29 Incorrect length indicates that the number of bytes contained in the storage areas assigned is nat
CHAN
PGRM
GElll equal to the number requested or offered.
CHKS
STOR PROT GEll 1 30 Program check indicates that the channel has detected a program error.
CHAN DATA GElll 31 Storage protect check indicates that the associated protect keys do not match.
CHAN CTRL
I
GEIOI
32 Channel data check indicates when an error is detected on any data transfer to or from an 1/0 device.
IF CTRL GEIOl 33 Channel control check indicates when there is any machine malfunction that affects channel controls.
CHAIN I GEi II 34
Interface control check indicates when there was an invalid signal combination or sequence on the
interface.
35 Chaining check indicates when there is a channel overrun. (channel assumed a wrong starting address
or count while waiting for the information - during input chaining operations only.)
FIGURE 147. SELECTOR CHANNEL ROLLER - POSITION 3
Appendix B--Syatem Control Panel (3/71) 167