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VIPER Technical Manual Detailed hardware description
© 2007 Eurotech Ltd Issue E 70
PC/104 16-bit memory read/write access cycles
Unsupported PC/104 interface features
The PC/104 bus features not supported by the VIPER are as follows:
• PC/104 IRQ9, IRQ14 and IRQ15 are not available under Windows CE as all
interrupt sources are fully utilized. Therefore the PC104I2 register is not available.
• DMA is not supported on the VIPER’s PC/104 interface. Therefore AEN is set to a
constant logical zero.
• Bus Mastering is not supported on the VIPER’s PC/104 interface. Therefore do not
connect another VIPER or any other master add-on board to the VIPER PC/104
interface.
• Shared interrupts are not supported on the VIPER’s PC/104 interface. Therefore do
not connect more than one add-on board to the same interrupt signal line.
• BALE is set to a constant logical one as the address is valid over the entire bus
cycle.
• The PXA255 PCMCIA memory controller does not support 8-bit memory read
accesses for common memory space.
AEN
BALE
SBHE
A<0:23>
MEMCS16
IOCHRDY
(S)MEMR/(S)MEMW
DATA (read)
DATA
(
write
)
VALID
VALID
VALID VALID
VALID
VALID