IBM System/370 145 Manual page 142

transferred to processor storage for these columns when cards are read
in format mode. FEED, READ only, and READ AND FEED commands with the
new format mode bit on in the operation code must then be issued to
cause read column eliminate to be effective. Reading in format mode
continues until the first feed type command without the format mode bit
on is issued or until unit exception status (end of file) on the 3505 is
accepted
by
the system.
Card stacking has been designed to require operator intervention less
frequently. Two 1750-card-capacity stackers that functionally provide
one logical stacker with a 3500-card capacity are standard. This is
achieved through implementation of an alternate stacking facility.
Initially, cards are placed in the first (or right-half) stacker and a
light on the operator panel is turned on to indicate that the right half
is the active stacker. When the right-half stacker becomes full, the
right active light is turned off, cards automatically begin stacking in
the second (or left-half) stacker if it is ready, and the left active
light is turned on. When the left-half' stacker becomes full, stacking
is automatically switched back to the right~half stacker if the operator
has removed all the cards from the right-half stacker and set the
stacker ready switch on the operator panel to indicate an empty right-
half stacker condition. Otherwise# a stacker-full indication is given.
ThUS, more than two and one-half times the number of cards can be
stacked in a 3505 as in a 2500-series card reader before operator
intervention is required. If care is exercised, cards can also be
removed from a stacker while cards are being placed in it, as can be
done with 2500-series readers.
If the optional Selective Stacker feature is installed, cards can be
directed under program control to a second logical stacker (third
physical stacker) with a capacity of' 1750 cards. Alternate stacking
into logical stacker 1 (right and left half) occurs as already
described. An unlimited amount of time is available in which to issue
the stacker select command. During this time the card is positioned at
a wait station.
A
3505 without the Selective Stacker feature installed
ignores stacker select commands and places all cards in logical stacker
1. If a stacker select command indicating pocket 3 is received by a
3505 with the Selective Stacker feature, the card is placed in stacker
2.
An error indication is not given in either situation.
'J'he standard Card Image feature for the 3505 provides the same
function as the Card Image or the Column Binary feature for other
readers. Read column eliminate can also be operative during column
binary mode reading.
The optional Optical Mark Read (OMR) feature provides the 3505 with
the ability to read up to a maximum of 40 columns of vertical marks on
an 80-column card. Both vertical mark fields and punched-hole fields
can be read in one pass of a card. Vertical marks can be preprinted on
cards in a nonreflective ink. Alternatively, marks can be made by hand
with a No. 2 pencil or equivalent, thus eliminating the necessity of
using special graphic pencils, as is required for mark sensing
operations on the 514 Reproducing Punch and the
519
Document Originating
Machine.
As
shown in Figure 20.30.3, the center of a vertical mark column is
coincident with a punch column. Vertical mark fields can begin at any
column and can be intermixed with punched-hole fields in any sequence,
subject to the following: Any vertical mark column must always be
preceded by at least one blank column (except for column 1) and followed
by at least one blank column (except for column 80). OMR card design,
nonreflective ink requirements, marking restraints, etc., are discussed
in detail in IBM 3505 Card Reader and IBM 3525 Card Punch Subsystem,
GA21-9124.
132
A Guide to the IBM System/370 Model 145