Read Checks - IBM 1620 Manual

1)
2)
3)
4)
Check transfer to MDR
If Op 37 check set of MBR from
zone translator
Read Checks
Typewriter
READ
Checks
MBR and READ Checks
Refer to Section IV (Core Storage)
MBR check may be caused by invalid
data in memory
1) Check Typewriter Bit Relays
2) Check input translator
3) Check typewriter keyboard
contacts and selector common
(False Read Check)
Check VRC Circuit
contacts (Timing Relationship pg. 3.3)
Scoping Methods
1) The input translator may be scoped by blocking a
typebar in its fully raised position with the type-
writer on-off switch in the off position. At this
time, the input translator is conditioned to accept
the bit{s) corresponding to the typebar raised.
2) The·transfer to MDR, and from MDR to MBR, may
be scoped by blocking a bit relay or group of
relays transferred and locking the system in a
trigger 30 operation. To lock in a trigger 30
operation, block the "B" advance pulse which
turns on the hold trigger.
3.2