Specifications

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Chapter 4
Programming Interface
This chapter describes the EPC-6A as seen by a program. Wherever possible, users should
avoid direct use of most of these facilities. Hardware features in common with standard
PCs should be accessed by standard BIOS calls. Hardware unique to EPC-6A, such as the
VMEbus interface should be accessed through a variety of software packages and drivers
available with the EPC-6A.
Memory Map
Memory at addresses between 0 and 4 MB (0FFFFFh) are mapped as follows:
I/O Map
The following defines the I/O addresses decoded by the EPC-6A. It does not define
addresses that might be decoded by the installed EXM.
Table 4-1. I/O Map
Range Content
000000h – 09FFFFh DRAM
0A0000h – 0BFFFFh Uncommitted, EXM bus or VIDBIOS
0C0000h – 0C7FFFh Uncommitted, DRAM, EXM bus or VIDBIOS
0C8000h – 0DFFFFh Uncommitted, mapped to EXM bus
0E0000h – 0EFFFFh Mappable window onto VMEbus
0F0000h – 0FFFFFh System BIOS
100000h – 3FFFFFh DRAM
400000h – F7FFFFh Uncommitted, EXM bus
F80000h – FFFFFFh BIOS ROM
Port Functional group Usage
00 DMA Channel 0 address
01 Channel 0 count
02 Channel 1 address
03 Channel 1 count
04 Channel 2 address
05 Channel 2 count
06 Channel 3 address
07 Channel 3 count
08 Command/status
09 DMA request
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