SD60C31 Datasheet, PDF (5/12 Pages) AUK corp – CMOS SINGLE-COMPONENT 8-BIT MICROCOMPUTER

SD60C31/P SD60C51/P
Pin Description(continued)
ALE : PIN 30 (DIP40), PIN 33 (PLCC44)
Address latch enable output pulse for latching the low byte of the address during
accesses to external memory.
In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency,
and may be used for external timing of clocking purposes.
Note : However, that one ALE pulse is skipped during each access to external data
memory.
If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH.
With the bit set, ALE is active only during a MOVX instruction. Otherwise, the pin
is weakly pulled high.
PSEN : PIN 29 (DIP40), PIN 32 (PLCC44)
Program store enable is the read strobe to external program memory. When the
60C51 is executing code from external program memory, PSEN is activated twice
each machine cycle, except that two PSEN activations are skipped during each
access to external data memory. PSEN is not activated during fetches from internal
program memory.
EA : PIN 31 (DIP40), PIN 35 (PLCC44)
External access enable. EA must be strapped to V_SS in order to enable the device
to fetch code from external program memory locations starting at 0000H up to
FFFFH.
If EA is strapped to V_CC the device executes from internal program memory unless
the program counter contains an address greater than 0FFFH.
XTAL1 : PIN 19 (DIP40), PIN 21 (PLCC44)
Input to the inverting oscillator amplifier and input to the internal clock generator
circuits.
NC : PIN1, 12, 23, 34 (PLCC44)
Non connection pins.
XTAL2 : PIN 18 (DIP40), PIN 20(PLCC44)
Output from the inverting oscillator amplifier
KSI-W001-000
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