TM 5-6675-320-14
Table 4-6. PROCESSING ClRCUITS FUNCTIONAL SEQUENCE OPERATION - Cont
Clock
Period
O p e r a t i o n o f C i r c u it
READ OPERATION - Cont
t6 t h r u t9
Microprocessor interprets instruction period and then exits mode by
setting STM, synchronize (SYNC), and synchronous memory complete
(SMC) to low.
Microprocessor also reads data from any of the following:
RAM and ROM on PCA A4
Registers on I/0 interface PCA A5
Registers on HP-IB PCA A2
Self-test registers on PCA A3
Interrupt registers on PCA A3
NOTE
Process of reading data and instructions from any of these locations is
accomplished in a similar manner as described above.
However, register
decoder circuits must be utilized to determine appropriate register to
a c t i v a t e.
First five data bits (IDA Ø-4) are decoded by register
decoder circuits and activated register accepts instruction or data
placed on data bus by microprocessor.
( 3 ) S e l f - t e s t .
Is initiated by a self-test flag on PCA A3 (flag II), which
o r i g i n a t e s a t s e l f - t e s t s w i t c h S 7.
PCA A3 then performs self-test steps according
to a program stored in ROM.
Test results are displayed on self-test lamps when the
microprocessor initiates a WRITE 13 (W13) and places the light sequence on the data
bus .
I f t e s t s e l e c t o r 6 i s s e l e c t e d t o t h e o n ( 2 ) p o s i t i o n , a n i n h i b i t s i g n a l i s g e n e r-
a t e d w h i c h i n i t i a t e s t h e b i d i r e c t i o n a l i n t e r f a c e b u s e s ( B I B ’ s ) a n d i s o l a t e s t he
microprocessor from the data bus.
Inhibit also sets U13 which places a preset
address onto the microprocessor data bus.
4-25
