Specifications

67
Software Interfaces
This chapter describes the software interface of the PCM-4330 PC/104 board
computer.
Address Summary of System Memory
A 1 MB address space is available in Real Mode and up to 4 MB physical memory
on-board in Protected Virtual Mode.
After a system reset the CPU resumes operation in Real Address Mode. Code
at address FFFFF0h is executed next. Therefore, the BIOS area must be paged into
the upper 64 kB segment of the 4 MB address space. From there a far jump into
segment F000h is performed.
5
HEX Address Name Function
00000000h - 0009FFFFh 640 kB User RAM
DOS application
programs
000A0000h - 000BFFFFh 128 kB Video RAM Display refresh memory
000C0000h - 000CBFFFh 40 kB VGA BIOS 40 kB Flash-Filings 8kB
000CC000h - 000EFFFFh 144 kB Extemsion ROM Extended BIOS area
000F0000h - 000FFFFFh 64 kB BIOS on-board BIOS area
00100000h - 003FFFFFh
On-board RAM
4 MB
Extended Memory in
Protected Mode only
00000000h - 00FFFFFFh
Off-board RAM
16 MB
On expansion boards (if
enabled in setup menu)
FFFF0000h - FFFFFFFFh 64 kB BIOS on-board BIOS area after reset
Table 24, Address Summary of System Memory
5.1