6526 tests

gistfile1.txt

Ports A and B each consist of an 8-bit Peripheral
Data Register (PR) and an 8-bit Data Direction Register
(DDR). 

If a bit in the DDR is set to the corresponding bit
in the PR is an output, if a DDR bit is set to a zero, the
corresponding PR bit is defined as an input. 

On a READ, the PR reflects the information present on the
actual port pins (PA0-PA7, PBOPB7) for both input and
output bits.


Situatie 1:
PA0             0000 1111

Schrijf DDRA:   1101 0100           (1 = output, o = input)
Lees PRA:       0000 1111



Situatie 2:
PA0             0000 1111

Schrijf DDRA:   1101 0100           (1 = output, o = input)
Schrijf PRA:    0000 1111
   naar PA0:    00?0 ?1??