Z80-PORTS(5) Port mapping Z80-PORTS(5)NAME
description of port mapping used by z80-mon for IN and OUT
DESCRIPTION
Because the IN and OUT instructions communicate with the outside their
effect is environment/OS dependend. Port access can be either directly
clock synchron or asynchron and buffered. In the later case all
effected ports by the IN and OUT instructions are realized as a binary
file named .Z80_ports buffering the data. Then this file must be read-
and writable and should contain 256 bytes. In the case, that only
directly synchron port access by other hardware components is wanted,
this file .Z80_ports should not exist, or must be at least nonreadable
to not interfere with the system bus.
The user has the option to reserve some ports for bank switching.
bank switching
The instruction OUT (n),A may select a certain bank, defined in the
file banks. The value of A selects the position the bank is mapped on.
Some banks ignore the value A, and are always mapped onto a predefined
position.
Two special ports for character input and output
are connected to stdin and stdout. Typically these are the ports 0 and
1 in UNIX. Appropriate hardware is already attached to enable nonblock‐
ing keyboard reading (be aware that this might interfere which z80-mon)
and output on a one line display inside z80-mon user interface.
SEE ALSOz80-mon(1), z80-banks(5), z80-keyboard(5), z80-memory(5)Z80-PORTS Version 2.3 08 Jun 2005 Z80-PORTS(5)
