TM 5-6675-318-14
Table 3-15. REGISTER FUNCTIONS
Function
Operation
Register
Read Self-Test
R
20
Write Self-Test
w
R e a d Confidence Test
21
R
Write to HP-IB Interface
W
Read HP-IB
R
22
W
W r i t e HP-IB
Read Front Panel & Paper
R
23
Advance
w
W r i t e to Paper Advance
Not Used
R
24
w
R
Inhibit Interrupt
25
w
Enable Interrupt
Read Front Panel
26
W r i t e Front Panel
Read Front Panel
R
27
W r i t e Front Panel
w
w . MOS and TTL bus drivers.
T h e MOS and TTL bus drivers are 3-state bidirec-
tional bus drivers (BIBs) which provide a two-way data transmission between the
B I B s U46 and U47 buffer the
microprocessor and the various circuits of the plotter.
microprocessor bus from the MOS bus which interfaces with the memory circuits and
These BIBs are enabled by delayed extended synchronous memory com-
the TTL BIBs.
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
D i r e c t i o n control for these BIBs also comes from PDR, while
BIBs U49 and U50.
the enable signal is generated in the memory timing circuits.
3-128
