
38
Data Device Corporation
www.ddc-web.com
BU-64703
D-03/06-0
16-bit bi-directional data bus.
signals are high impedance inputs.
46
D10 (I/O)
D00 (I/O) (LSB)
42
D01 (I/O)
47
D02 (I/O)
48
D03 (I/O)
D04 (I/O)
43
49
D05 (I/O)
41
D06 (I/O)
53
D07 (I/O)
52
D08 (I/O)
57
60
D09 (I/O)
58
D11 (I/O)
55
D12 (I/O)
54
D13 (I/O)
56
D14 (I/O)
59
D15 (I/O) (MSB)
PIN
SIGNAL NAME
TABLE 9. DATA BUS (16)
DESCRIPTION
1
L_BRO (O)
Latched Broadcast. This two-state output signal is latched following receipt of a new command word. For a broadcast
command, this signal outputs a value of logic "1". For a non-broadcast message, this signal will output logic "0".
2
T / R
Transmit/Receive. This two-state output signal is latched following receipt of a new command word. For a transmit mes-
sage, this signal will output a value of logic "1". For a receive message, this signal will output logic "0".
75
SA2 (O)
Subaddress. These five two-state output signals are latched following receipt of a new command word. They provide the
subaddress field of the received command word.
PIN
78
WC / MC /
CWC2 (O)
Word Count/Mode Code/Current Word Count. Following receipt of a new command word, these five two-state output sig-
nals provide the contents of the command word's Word Count/Mode Code field.
For a non-mode code receive message, the contents of WC/CWC are updated and incremented to reflect the value of the
current data word being transferred to the system (in non-burst mode), or to the internal FIFO (in burst mode). CWC
increments from 0 to the value of the Word Count field - 1 during the message.
At the end of a non-mode code receive message in burst mode, the contents of CWC will then increment from 0 to the
value of the word count field -1, as each word is transferred from the internal FIFO to the external system over D15-D0. In
burst mode, it takes three clock cycles to transfer each word to the external system.
For a non-mode code transmit command, the value of CWC starts from 0 and increments to the value of Word Count - 1,
as each word is read from the external system and transferred to the SSRT Mark3.
For a mode code command, the WC/CWC outputs the command word mode code field, which remains latched through
the end of the message (until receipt of a subsequent command word).
TABLE 10. COMMAND / ADDRESS BUS
SIGNAL
SA4 (O)
SA3 (O)
SA1 (O)
27
12
7
SA0 (O)
74
WC / MC /
CWC4 (O) (MSB)
WC / MC /
CWC3 (O)
WC / MC /
CWC1 (O)
33
19
DESCRIPTION
13
WC / MC /
CWC0 (O) (LSB)
18