xbeaver bus extenders

Instantiation

The external bus extender is added to the emulation using the line:-
board <port-address> extbus <target-base> <map-length> <options> <device-name> [<port=value>]

The parallel port bus extender is added to the emulation with the line:-
board <port-address> pptbus <target-base> <map-length> <options> <device-name> [<port=value>]

and the Serial Peripheral Interface mapper is added to the emulation using the line:-
board <port-address> spibus <target-base> <map-length> <options> <device-name> [<port=value>]

and the internal bus mapper is added to the emulation using the line:-
board <port-address> intbus <target-base> <map-length> <options> <bus-name> [<port=value>]

Options

OptionDescription
IExternal Bus inverts data on read and write
HHigh 8 bits of Z80 i/o address used as port address
XHigh 8 bits of Z80 i/o address passed through to high 8 bits of target address
SLocal bus is mapped as separate address/data pair
MTarget bus is mapped as address/data pair
NShort address setup not permitted (With option S)
ZShort address setup is based at address zero (With option S)
PSet targetting address to 10 bits (0x000..0x3ff)
LSet targetting address to 16 bits (0x0000..0xffff)
LPSet targetting address to 24 bits (0x000000..0xffffff)
RAllow target reads
WAllow target writes
TTrace IO cycles

IO Ports

When option S is used
OffsetAccessFunction
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
0R/WAddress register
1R/WData register
When option H is used
OffsetAccessFunction
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
0R/WData register
Otherwise
OffsetAccessFunction
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
0..<map-length-1>R/WAccess to target bus