APPENDIX A: GG2 Bus+ Specifications 


The GG2 Bus+ bridgecard lets you lets you use AT-compatible IBM plug-in 
cards in your Amiga PC slots as Amiga devices, controlled by Amiga 
software.

PC HARDWARE SUPPORT

The GG2 Bus+ bridgecard will support almost all non-DMA AT-compatible 
(8 MHz bus capable) PC plug-in boards.  This includes such popular items
as internal modems, multi-IO boards, non-DMA ethernet boards, VGA boards,
A/D boards, etc.  Access  to the PC cards is at full Amiga Zorro II bus
speed unless wait state support is turned on.

The following IBM AT bus signals are supported:

	IO address space from hex $0000 to $7FFF (first 32K)
	
	Memory address space from hex $90000 to $FFFFF  (440K)

	16 bit data bus

	All AT bus interrupts

	Wait states (IOCHRDY signal) for both IO and memory access

	14.31818 MHz clock (OSC signal) from on-board crystal oscillator

	7.2 MHz processor clock (CLK signal)

	BALE signal


AMIGA HARDWARE DETAILS

The GG2 Bus+ bridgecard occupies one Zorro II slot aligned with an IBM AT
slot in an Amiga 2000, 2500, 3000, or 4000.  It has essentially the same form
factor as a normal bridgeboard.  You will need at least one additional open
PC-AT slot for your plug-in PC card.  The GG2 Bus+ requires 1 Megabyte 
of autoconfig memory space to be available to correctly map all of the 
PC memory locations.  All address and data lines to the PC bus are buffered
to avoid loading.


ON-BOARD REGISTERS

The GG2 Bus+ bridgecard includes 3 software accessible registers for 
the control of wait state and interrupt support.  The default setting of 
wait state support after reset is controlled by an on-board jumper. 

See  Appendix B  for details.