Toshiba TLCS-90 Series Data Book page 73

TOSHIBA
RESET (Input)
TMP80 C49AP /-6) TMP 80C39AP /-6) TMP80G49AF /-6)
TMP80C49AT,TMP80C39AT
Active Low signal which is used to initialize the Processor.
during the power down mode.
Also used
ALE (Oupput)
Address Latch Enable. This signal occurs once during each cycle and is
useful as a clock output. The negative edge of ALE strobes address into
external data and program memory.
PSEN (Output)
Program Store Enable. This output occurs only during a fetch to external
program memory (Active Low).
SS
(Input)
Single step input can be used in conj unction wi th ALE to "single step"
processor through each instruction when SS is low the CPU is placed into a
wait state after it has completed the instruction being executed. Also
used during the power down mode.
EA (Input)
External Access input which forces all program memory fetches to reference
external memory. Useful for emulation and debug and essential for testing
and program verification. (Active High)
XTAL 1 (Input)
One side of crystal input for internal oscillator. Also input for exter-
nal source.
XTAL 2 (Input)
Other side of crystal input.
MCU48-63