Commodore Amiga A2000 - ADDRESS SPECIFICATION Table

from the bus to the board. This allows the board to respond to the AUTOCONFIG process.
When the switch is set the other way, it should be wired such that the input to the board
is forced high This will disable the AUTOCONFIG of the board.
Set the switch so that the CONFIGIN* line is forced high, then bring up the system. Your
board will be invisible to the system software. Activate a debugger, and flip the switch,
Your board should now respond at the normal $E80000 address. Your view of the board is
identical to what the operating system sees when configuring your board. You can
compare the bits with the expected values.
NOTE
The board to be debugged must be the last board in the system (closest to the PC slots,
away fm the power supply.) Boards downstream of the board to be debugged will not be
configured by the system.
ADDRESS SPECIFICATION Table
The following Table describes the board identification information and AUTOCONFIG
registers which appear in the first $80 bytes of an AUTOCONFIG board at configuration
time.
NOTES
o Identification information is stored in the high nibbles of the even (word) addresses at
the start of an AUTOCONFIG board. For example, the first two words of a board might
contain $Cxxx 1xxx. The valid information in these first two words would be the $C high
nibble of the word at offset $00). then the $1 (high nibble of the word at offset $02).
Much of the information is interpreted by combining several nibbles, with low to high
address nibbles containing high to low order parts of the resulting value.
o All nibbles of information, except for those at offsets $00/02 and $40/42, are stored in
an inverted (one's complement) form and must be exclusive OR'd with $F before
interpreting them according to the Table below. Unused nibbles (the three other nibbles in
each word) may not be assumed to contain any particular value. All values written to the
AUTOCONFIG area, including the assigned address, are written uninverted.
o All addresses are shown here as offsets from the base address $E80000 where boards
appear at configuration time, so offset $02 is at $E80002, offset $04 at $E80004, etc.
- Appendix G 337 -