EER-018
Introduction to Digital Computers
Lecture 29
Reminder - Homework: # 10 (on the web) - put in portfolio - solutions
available on Friday.
RAM and I/O Port Circuitry
Let's look at inputs and outputs of the 8-bit RAM word or I/O port.
RAM
DATA connection
READ input
WRITE input
Input Port
DATA connection
READ input
Output Port (with readback)
DATA line connection
READ input
WRITE input
I/O Port and DDR
DATA connection
READ DDR input
WRITE DDR input
READ PORT input
WRITE PORT input
Address Decoding
Internal RAM - $00C0-$00FF
I/O PortA - $0000
DDRA - $0004