ZiLOG eZ80

eZ80
®
CPU
User Manual
UM007714-0908 I/O Space
47
I/O Space
A separate I/O space may include both on- and off-chip peripheral devices. The eZ80
®
CPU is capable of addressing a 64 KB I/O space with 16-bit addresses. The memory and I/
O space share the same 24-bit address and 8-bit data buses. However, the I/O peripherals
are accessed using special I/O instructions including IN, OUT, and TSTIO. Whenever an
I/O instruction is executed the upper byte of the 24-bit address bus is undefined.
Refer to the eZ80
®
and eZ80Acclaim!
®
product specifications for more information on
using the I/O address space and the on-chip I/O peripherals.