INCREMENT ADDRESS - This line pulses low to increment
the external instruction addressing counter.
POWER UP CLEAR - This line should be pulsed low
HANDSHAKE FAIL / INTERRUPT REQUEST
RT: This line pulses low to inform the subsystem that it has
not responded to a data transfer request to take place.
BC: This line pulses low to generate an interrupt to the BC
RESET - This line when low, forces the internal circuitry to
reset to the quiescent initialised state. This is a ‘TTL’ level
input on both devices and an open-drain output on the
MA3690. The subsystem should drive this line via an open
drain/collector device with external pull up fitted.
IN COMMAND - When low this line indicates that the terminal
is currently servicing a command word.
END OF TRANSMISSION - When low this line indicates that
the selected bus is quiet and hence available for use.
RT0 / RT1 Inputs
REPLY TIMEOUT DECODE - These lines on the MA3690
allow four different timeout values to be used. On the
MA3693, the RT1 signal is not available and is pulled down
RT1 RT0 Timeout (us)
This line will pulse low to abort execution of the current
command if an error is detected.
HIGHWAY LINES - 16 line bidirectional Output data highway.
(B0 = LSB).
COMMAND LOAD - When low this line indicates that the
word on the data highway should be loaded into the
transmitter for transmission with a command sync.
DATA LOAD - When low this line indicates that the word on
the data highway should be loaded into the transmitter for
transmission with a data sync.
OUTPUT BUFFER FULL - When low this line indicates that
the transmitter output buffer is full and cannot be overwritten.
Note: Under normal operation, option 00 should be used.
The measurement is taken between mid parity and mid sync
- measured at PDIN/NDIN terminals.
TERMINAL FLAG - This line is available only on the 64-pin
MA3690 and on the MA3693 (where it replaces RT1). The
line indicates the state of the Terminal Flag bit in the Status
Word, and can be inhibited by the mode code Inhibit
Terminal Flag. This is an active LOW signal.
These lines are for test purposes only and for normal chip set
operation must both be tied low.
VALDRN Inter-chip (CMOS)
VALID DATA RECEIVED - When low this line indicates that a
valid data word has been received and is on the data
VALCRN Inter-chip (CMOS)
VALID COMMAND RECEIVED -
RT: When low this line indicates that a valid command word
for this RT has been received.
BC: When low this line indicates that a valid word with a
command sync has been received.
REMOTE TERMINAL/BUS CONTROLLER - When high the
terminal will function as an RT.When low the terminal will
function as a bus controller.
4MHz system clock.