Acorn computer Z80 Second Processor, Service Manual

Page: 19 / 58

The fo11owing tables show the relative address and type of each
register in the Tube, firstly for the Host system, and secondly for
the parasite system (second processor).
Table 1 Host system registers
Address Read
000 Status flags and Register 1 flags
001 Register 1 (24 byte FIFO read only)
010 Register 2 flags
011 Register 2 (1 byte read only)
100 Register 3 flags
101 Register 3 (2 byte FIFO read only)
110 Register 4 flags
111 Register 4 (1 byte read only)
Address Write
000 Status Flags
001 Register 1 (1 byte write only)
010
011 Register 2 (1 byte write only)
100
101 Register 3 (2 byte FIFO write only)
110
111 Register 4 (1 byte write only)
Table 2 Parasite system registers
Address Read
000 Status flags and Register 1 flags Al Fl P V M J I Q
001 Register 1 (1 byte read only)
010 Register 2 flags
011 Register 2 (1 byte read only)
100 Register 3 flags
101 Register 3 (2 byte F1FO read only)
110 Register 4 flags
111 Register 4 (1 byte read only)
Address Write
000
001 Register 1 ( 24 byte FIFO write only)
010
011 Register 2 (1 byte write only)
100
101 Register 3 (2 byte FIFO write only)
110
111 Register 4 (1 byte write only)