IBM System/32 Introduction And Maintenance Manual page 179

A half line space operation is initiated by setting
the carriage reverse bit (bit 4) in a control load
command OOCL) with a modifier of A. Half index
mode is reset by bit 5 of the command and the
half index feature card is reset by bit 5 of the
command, dropping carriage go, or resetting the
printer attachment.
Half index complete indicates that the 5 'fast'
pulses to the printer attachment have been gener-
ated and the completion of the index operation
is under control of the carriage advance digital
control in the printer.
32 MS
-1t-
~
'Fast' Carriage Advance Pulses
-II-
32 MS
Carriage Go
Carri Advance to
Carriage Shift Register and
Carriage Drive
Carria Advance to
Printer Adapter and
Carriage Space Counter
Half I ndex Complete
A
A
B
B __________________________
~
Belt Printer 285 Ipm 4-89