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test. The module requires a half slot in the 990
chassis and interfaces with a 990 communications
interface module (not included) via the top-edge
connector and cable. The modem must be adjacent
to the 990 communications interface module in the
chassis.
The 990 synchronous-modem kit is similar to the
990 asynchronous-modem kit, except this kit
provides a Bell-201 C-equivalent (2400-baud) modem
for synchronous communication. The modem
provides an internal clock and loop-back for a self-
test.
The auto-call kit provides for CPU calling via dial
pulse or tone signals to telephone-switching circuitry.
The CPU test of an auto-call module is provided by
access to internal states. The module plugs into a
half slot in the 990 chassis and interfaces with a
synchronous or asynchronous modem by a top-edge
cable. The auto-call module must be adjacent to a
modem in the chassis.
A communications-software package is available
from Texas Instruments. This package requires
considerable customizing to meet the needs of an
individual customer.
Special Interface Devices
Special interface devices include units that are not
supported by device service routines under the DXIO
operating system. They are not supported because
they are application dependent or because they
interface with equipment that is not part of Texas
Instruments standard line of I/O devices. Use of
these peripheral devices will require the user to
prepare a device service routine and link it to the
DXIO operating system or to the appropriate
application .program.
EIA Data Modules
The Electronics Industries Association (EIA) data
modules provide a general-purpose, 16-bit, parallel
I/O interface between the 990 processor and any
external device(s) that requires EIA signal levels. The
jumper-wire option card provides options of sixteen
inputs and sixteen outputs or fifteen inputs, fourteen
outputs, and one maskable interrupt.
An interrupt request can be polled regardless of
the state of the interrupt mask. A module requires a
half slot in the 990 chassis and interfaces with the
CRU bus.
TTL Data Modules
The transistor-transistor-Iogic (TIL) data modules
provide two-way parallel interface between the 990
54
processor and devices that require TTL interface
signals. The jumper-wire option card provides
options for sixteen inputs and sixteen outputs or
fifteen inputs, fourteen outputs, and one maskable
interrupt.
An interrupt request can be polled regardless of
the state of the interrupt mask. A module requires a
half slot in the 990 chassis and interfaces with the
CRU bus. Top edge mates with a ribbon-cable
connector.
TTY /EIA Terminal
Interface Module
The Teletypewriter/Electronics Industries Association
(TTY / EIA) terminal interface module interfaces 990
processors with terminal devices, such as VDTs and
printers, that use EIA-standard RS-232-C or 20-
milliampere TTY current-loop interfaces. (Modems
should be interfaced via the communications
interface module because several data-set control
signals are omitted from the TIY lElA module.) The
TTY
I
EIA module occupies a half slot in the 990
chassis and interfaces with the CR U bus. The
following baud rates can be selected by jumper wires
on the card: 110, 300, 1200, 4800, and 9600.
32-Bit Input/Transition
Detection Module
The 32-bit inputl transition detection module
monitors up to thirty-two TTL input lines. Any or
all of the lines can be read (sixteen at a time) by
the 990 CPU. The module can generate an interrupt
when a transition occurs on any line and can supply
the address and current state of the interrupting line.
A programmable mask determines which lines
ge!J.~r~te aflint~rruPt
on
transitio~
or the entire
board can be masked. The module requires a full
slot in the 990 chassis, although it physically
occupies only a half slot. The module uses all thirty-
two CR U channels dedicated to a full slot. The top
edge mates with two ribbon-cable connectors on the
termination-panel cables.
32-Bit Output-Data Module
The 32-bit output-data module provides thirty-two
buffered output lines; each line can be addressed as
a single line or as a member of a group of two to
sixteen lines. Open-collector transistors on the output
can sink 200 milliamperes and hold off up to 50
volts dc. This half-sized module requires a full slot
in the 990 chassis because it uses all thirty-two CR U
channels dedicated to the slot. The module interfaces
with two ribbon-cable connectors on the termination-
panel cables.
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