User manual

DIGITAL-LOGIC AG MSM800SEV/SEL/BEV/XEV/XEL Detailed Manual V1.7
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2.9. MSM800SEV/SEL Incompatibilities to a Standard PC/AT
2.9.1. PC104 BUS / ISA BUS
An onboard LPC to ISA-bridge makes it possible to expand the functionality of the board with additional
PC/104 cards.
Unfortunately, because of the transformation from LPC to ISA it is not possible to realize a 16bit access. This
does not mean that these cards cannot be used, but that the 16bit access is divided into two. Therefore the
access to these cards is a little bit slower.
The LPC support the following bus cycles:
Cycle Type Sizes Supported Comments
Memory Read 1Byte Optional for both LPC hosts and peripherals
Memory Write 1Byte Optional for both LPC hosts and peripherals.
I/O Read 1Byte Optional for peripherals.
I/O Write 1Byte Optional for peripherals.
DMA Read 1, 2, 4Byte Optional for peripherals.
DMA Write 1, 2, 4Byte Optional for peripherals.
Bus Master Memory Read 1, 2, 4Byte Optional for both LPC hosts and peripherals, but strongly
recommended for hosts.
Bus Master Memory Write 1, 2, 4Byte Optional for both LPC hosts and peripherals, but strongly
recommended for hosts.
Bus Master I/O Read 1, 2, 4Byte Optional for both LPC hosts and peripherals.
Bus Master I/O Write 1, 2, 4Byte Optional for both LPC hosts and peripherals.
Firmware Memory Read 1, 2, 4, 128Byte Optional for both LPC hosts and peripherals.
Firmware Memory Write 1, 2, 4Byte Optional for both LPC hosts and peripherals.
This means, all Non-BusMaster I/O and MEM Cycles are only 8bit wide and never 16bit wide. 16bit
data transfer is available in the BusMaster modus only.
Attention!
With the BEV/BEL/XEV/XEL versions, this limitation is solved by using a PCI-ISA bridge.
The disadvantage is that now 2 PCI devices are onboard and there are only 2 external PCI
slots available.