I/O Map
I/O Map After Power-up/Reset
The 386EX I/O has 64KB of I/O space. This is routed to the default
bus (STEbus or PC/104) except for the following locations. I/O
locations 22h and 23h are reserved for the I/O map configuration
register REMAPCFG. This register can change the way the I/O
space is set up for the 386EX. The monitor program sets the 386EX
up into Expanded Mode by default. This allows all the on-chip
peripherals to be mapped to address between F000h and F8FFh.
Programmable chip select line CS2 is used to select on-board
peripherals (STEbus interrupt control, interrupt out and bus timeout
interrupt clear, SVIF1 port). As CS2 can be programmed to be
anywhere in the I/O space (or, indeed, the memory space) the
location of this on-board peripheral control register block may be
relocated to any convenient location. In order to allow the maximum
space for I/O expansion on STEbus or PC/104 the monitor program
sets this register block location up to start at FC00h.
PC/104 is the only expansion bus available on SBC variants.
J539 TARGET386EX
2192-08270-000-000
Section 4. Using the TARGET386EX
Page 20
PC/104 (default)
STEbus (CS3-6)
SVIF1 Port
General Control Register 1 (repeat)
General Control Register 1
General Control Register 0 (repeat)
General Control Register 0
STEbus Control Register (repeat)
STEbus Control Register
PC/104 (default)
STEbus (CS3-6)
On-chip peripherals (Interrupt controllers, timers, UARTS)
PC/104 (default)
STEbus (CS3-6)
386EX 16bit REMAPCFG
register (not movable)
STEbus or PC/104
FFFFh
FC0Fh
FC0Ch
FC07h
FC06h
FC05h
FC04h
FC01h
FC00h
F8FFh
F000h
EFFFh
0023h
0022h
0000h
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