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AMX Mouse: Difference between revisions
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Add details about AMX Pagemaker and other apps here. | Add details about AMX Pagemaker and other apps here. | ||
== Ports == | |||
Port mapping is via A5, A6 and A7. | |||
These are decoded by the button reader ( Port 223 or 0xDF ) and directly by the z80 PIO chip, which responds to any combination of these address lines while a7 is low. This is because of the following mapping. | |||
A5=A/!B select. | |||
A6=D/!C select. | |||
A7=Chip Enable. | |||
This results in four useable ports for the z80 PIO - | |||
Port 31 ( 0x1F ) | |||
Port 63 ( 0x3F ) | |||
Port 91 ( 0x5F ) | |||
Port 127 ( 0x7F ) | |||
Also, the button decode is performed through direct I/O and pulling the relevant data line low. The button port is | |||
Port 223 ( 0xDF ) | |||
Reading from this port will result in reading the mouse buttons. | |||
LMB - Bit 7 low when pressed. | |||
MMB - Bit 6 low when pressed. | |||
RMB - Bit 5 low when pressed. | |||
== Circuit Layout == | == Circuit Layout == | ||
