Motorola MVME2300 Series - Manual (Page 67)

ISA Local Resource Bus
http://www.motorola.com/computer/literature 1-43
1
VME Geographical Address Register (VGAR)
The VME Geographical Address register is an 8-bit read-only register
located at ISA I/O address x1006. This register reflects the states of the
geographical address pins at the P1 connector.
Emulated Z8536 CIO Registers and Port Pins
Although MVME2300 series boards do not use a Z8536 device, several of
its functions are emulated within an ISA Register PLD. These functions
are accessed by reading/writing the Port A, B, C Data registers and Control
register. Note that the Pseudo IACK function is not implemented in the
MVME2300 series.
Emulated Z8536 Registers
The MVME2300 series implements the Z8536 CIO functions according to
the following table.
REG VME Geographical Address Register - Offset $1006
BIT SD7 SD6 SD5 SD4 SD3 SD2 SD1 SD0
FIELD GAP# GA4# GA3# GA2# GA1# GA0#
OPER READ ONLY
RESET X X X X X X X X
Table 1-20. Emulated Z8536 Access Registers
PCI I/O Address Function
0000 0844 Port C’s Data Register
0000 0845 Port B’s Data Register
0000 0846 Port A’s Data Register
0000 0847 Control Register