Rainbow-electronics W78C32C Manuel d'utilisateur télécharger pdf (Page 4)

W78C32C

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PSEN

Program Store Enable Output, active low.

PSEN

enables the external ROM onto the Port 0

address/data bus during fetch and MOVC operations.

PSEN

goes to a high state during reset with a

weak pull-up.

XTAL1

Crystal 1. This is the crystal oscillator input. This pin may be driven by an external clock.

XTAL2

Crystal 2. This is the crystal oscillator output. It is the inversion of XTAL1.

VSS, VCC

Power Supplies. These are the chip ground and positive supplies.

BLOCK DIAGRAM

SFR

Port 0

Port 1

Port 2

CPU

Data Bus

Port 3

Alternate

Serial

Port

Timer 0

CORE

Interrupt

Timer 1

RAM

256

Bytes

Alternate

Timer 2

INT 1

INT 0

1 2 3 4 5 6 7 8 9 ... 13 14

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Rainbow-electronics W78C32C Manuel d'utilisateur Page 4