TM 5-6675-323-14
Table 3-15. REGISTER FUNCTIONS
Function
Operation
Register
Read Self-Test
20
Write Self-Test
R e a d Confidence Test
21
Write to HP-IB Interface
22
Read HP-IB
W r i t e HP-IB
Read Front Panel & Paper
23
Advance
W r i t e to Paper Advance
24
Not Used
25
Inhibit Interrupt
Enable Interrupt
26
Read Front Panel
W r i t e Front Panel
27
Read Front Panel
W r i t e Front Panel
T h e MOS and TTL bus drivers are 3-state bidirec-
w . MOS and TTL bus drivers.
tional bus drivers (BIBs) which provide a two-way data transmission between the
microprocessor and the various circuits of the plotter. BIBs U46 and U47 buffer the
microprocessor bus from the MOS bus which interfaces with the memory circuits and
the TTL BIBs.
T h e s e BIBs are enabled by delayed extended synchronous memory com-
The direction that these BIBs are driving is controlled by the
p l e t e (DXSMC).
microprocessor generated processor driving (PDR). When PDR is low, the BIBs drive
out to the bus, and with PDR high, the BIBs drive toward the microprocessor.
Further buffering is provided for the HP-IB circuitry and the front panel by the
BIBs U49 and U50.
D i r e c t i o n control for these BIBs also comes from PDR, while
the enable signal is generated in the memory timing circuits.
3-128
