Detailed Interface Discussion; Full Duplex Tty /Eia Module-To-Model 990 Computer Interface - Texas Instruments 990 Maintenance Manual

~-------
~
945408-9701
Table 4-3. Multiplexer Output for CRUBIT,12-15
CRUBIT,12-15 Output
0000 RVBR7
0001 RVBR6
0010 RVBR5
0011
RVBR4
0100 RVBR3
0101 RVBR2
0110 RVBRl
0111 RVBRO
1000
XMTGO
1001 TIM ERR
1010
RC RD I
1011 WRQ
1100
RRQ
1101 DCDDI
1110 DSRDI
1111 INT
4.3 DETAILED INTERFACE DISCUSSION
Figure 4-5 shows the interfaces between the Full Duplex TTY/EIA Module and a Model 990
Computer and both a current-loop (TTY) device and an EIA device. All the interfaces are shown
in one diagram even though the module can be used only with a current-loop device or an EIA
device for a given set of jumper plug connections. The following paragraphs describe the signals on
the module's interfaces. ·
4.3.1 FULL DUPLEX TTY/EIA MODULE-TO-MODEL 990 COMPUTER INTERFACE. The
following paragraphs describe the TTY /EIA Module-to-Model 990 Computer interface.
4.3.1.1 CRUDATAOUT. CRUDATAOUT is serial information from the computer to the mod-
ule. The 16 bits of data represented by CRUD AT AOUT are addressable, and provide both data
and control signals for the module. Figure 4-6 illustrates the information contained on
CRUDATAOUT.
Data Character. The first eight bits of information are data bits to be transmitted to the
peripheral device.
Data Terminal Ready ( DTR). Logic 1 sets the data terminal ready latch.
Request To Send (RTS). Logic 1 sets the request to send latch.
Clear Write Request (CLRWRQ). Logic 0 or l resets write request flag.
27
Digital Systems Division