IBM System/370 145 Manual page 119

The 3211 -can also be used to print documents that can be read by the
1287 Optical Reader and the 1288 Optical Page Reader. When the optional
OCR Print package is installed on the 3211 Printer, one of two available
3216 OCR cartridges, each with 48 graphics, can be used.
The 3211 attaches to a 3811 control unit. Unlike some models of the
2821 control unit, which can handle multiple devices, a 3811 controls
only one 3211 Printer. The commalnds used for a 1403 printer are a
compatible subset of those provid'ed for the 3211 printer,. Print, skip,
and space commands for the two printers are identical.
New features of the 3211 inclmle a powered forms stacker, an
automatic platen, and a tapeless ~carriage. The powered stacker
mechanism is se1f-adjusting and aliitomatically rises in increments as the
stack of paper mounts. This ensmres that the stacker mechanism is
always the same distance above tbe top of the stack of forms. The rate
of rise during each increment is determined by the setting of the
stacker rate knobi which can be adjusted by the operator to produce the
best condition for the thickness of the forms being stacked. The
stacker also can be raised or lowered manually.
When forms are inserted, the plrinter _platen automatically positions
itself close to the train cartridqe in accordance with the thickness of
the forms. Thus, correct clearanc:::e between the platen and the cartridge
is achieved without operator intelrvention. Because of its automatic
forms thickness sensing, the 3211 is sensitive to forms with a different
degree of thickness at each edge. (For forms limitations, see IBM 3211
Printer, 3216 Interchangeable Train Cartridge, and 3811 Printer Control
Unit Component Description ~ ~:!r-ator's Guide, GA24-3543.)
Forms control paper carriage tape loading and unloading by the
operator is eliminated by implementation of a tapeless carriage feature
for the 3211. Forms spacing and skipping are controlled by a program-
loaded forms control buffer (FCB) contained in the 3811 control unit.
The FCB contains 180 storage positions, each of which corresponds to
a print line, that is, a single space of the carriage. Tpus, forms up
to 22.5 inches in length can be ac:commodated at eight lines per inch
spacing (or 24 inches at six lines; per inch). Up to twelve channel
codes (1-12), correspond-ing to
thE!
twelve channel positions of the paper
carriage tape used on a 1403 Print:er, can be stored in the appropriate
buffer line positions _ to control c:arriage skipping. The FCB can be
considered to contain a storage inlage ~f a carriage control tape.
A carriage control address regi.ster is used to address the FCB and
maintain correct line position wit.h respect to the form. This register
is incremented as space and skip commands, which cause the form to
advance, are issued. When a SKIP TO CHANNEL command is executed, the
carriage control address register is incremented and the form moves
until the channel specified is sensed in a line position in buffer
storage. If the requested channel number is not found in the buffer,
forms movement stops after address· position 1 (line 1) has been sensed
twice. This prevents runaway for
illS
skipping.
A flag in a buffer storage line position is used to indicate the last
line of the form, for forms shorter than 180 lines. A flag bit is also
used in the first buffer storage position to indicate six or eight lines
per inch spacing. The FCB is loaded with the desired forms spacing
charactel::S via a LOAD FCB command issued by a program. An error
indication is given if an end-of-page flag is- not present or if an
invalid carriage code is loaded.
The 3811 includes a new indexing capability as a standard feature.
With this facility, a print line can be offset to the right by up to 30
print positions (3 inches) without operator intervention or program
A Guide to the IBM System/310 Model 145 109