AT&T 3B2/300 Technical Reference Manual page 33

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Model DQP-10 Printer.
The Model DQP-10 printer is a dot-matrix, serial, impact printer capable of
bidirectional printing at 120 characters per second. At six or eight vertical lines per inch, the DQP-10
printer will print up to 80 characters per line with 10 characters per inch. Single sheet (8.5 x 11 inches)
or continuous fanfold paper, up to 10 inches wide, can be used.
Model 470 and 475 Printers.
The Model 470 and 475 printers are compact, desktop, dot-matrix,
impact printers. They are capable of bidirectional printing at speeds up to 120 characters per second.
They can print up to 132 characters per line, in a compressed font mode, at 16.8 characters per inch.
The friction paper feed and integral tractor/pin feed mechanism can handle paper up to 10 inches wide.
The only difference between the two printers is the type of interface. The Model 470 printer is
equipped with a 36-pin parallel interface; the Model 475 printer is equipped with a serial RS-232C
interface.
Model 5310 and 5320 Printers.
The Model 5310 and 5320 printers are dot-matrix, bidirectional,
logic-seeking printers offering sophisticated graphics capabilities. They can print up to 200 characters
per second. These printers offer a wide range of form and paper handling options. Carriage size and
maximum characters per line are the differences between the two printers. The Model 5310 has a
80-column carriage; the Model 5320 has a 132-column carriage. The Model 5310 can print up to 132
characters per line; the Model 5320 can print up to 220 characters per line.
Model LQP-40 Printer.
The Model LQP-40 printer is a daisy-wheel, letter-quality, serial/parallel
printer with a 48,000-byte data buffer. At six or eight vertical lines per inch, the LQP-40 printer uses
proportional fonts with speeds up to 18 characters per second. Single sheet (8.5 x 11 inches) or
continuous fanfold paper, up to 16.5 inches wide, can be used.
Model 455 Printer.
The Model 455 printer is a daisy-wheel, letter-quality printer capable of speeds
up to 55 characters per second. The printer is compatible with both serial and parallel interfaces.
Friction and tractor feeds will handle paper up to 15 inches wide. As many as 197 characters can be
printed on a single line, and a variety of font styles can be obtained by changing the daisy wheel.
RAM Expansion
The 3B2/300, 310, and 400 computers can be equipped with a maximum of two memory cards to
form the RAM. RAM is expandable in 1-megabyte increments to the maximum size of 4 megabytes. A
power supply upgrade is required for 3B2/300 computers with a red ON/STANDBY switch to expand
RAM to 3 or 4 megabytes.
A 3B2/500 computer can be equipped with a maximum of two memory cards. These memory
cards can be 2 megabytes or 4 megabytes, up to the maximum capacity of 8 megabytes.
The 3B2/600, 700, and 1000 computers can be equipped with a maximum of four memory cards.
RAM is expandable in 2-megabyte increments to the maximum size of 16 megabytes for the
3B2/600 computer or 64 megabytes for the 3B2/700 and 1000 computers.
Hard Disk Expansion
Additional hard disk drives can be added to an existing 3B2 computer. The hard disks are either
ST-506 type hard disks or SCSI hard disks, according to the associated computer. Two sizes of ST-506
hard disk drives are available: 30 megabytes and 72 megabytes (formatted). The 3B2/300 and
310 computers can support a maximum of six hard disk drives (one in the computer cabinet and five in
two AT&T/XM cabinets) for a maximum of 432 megabytes of ST-506 hard disk memory. The
3B2/400 computer can support a maximum of ten hard disk drives (two in the computer cabinet and
eight in AT&T/XM cabinets) for a maximum of 720 megabytes of ST-506 hard disk memory. Each
AT&T/XM cabinet can house a maximum of three hard disk drives.
Additional hard disk drives can be added to an existing 3B2 computer using a SCSI. A SCSI Host
Adapter card provides the interface between the computer and the SCSI bus. The SCSI hard disks are
either 147 megabytes (formatted), 300 megabytes (formatted), or 600 megabytes (formatted). Many
combinations of the different sizes of hard disks can be produced for over 14 gigabytes of external
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