Specifications

Theory of Operation

EPC-100 Hardware Reference 4-5

Range Content Cacheable

00000000 - 0009FFFF First 640 KB of DRAM (DOS memory) yes

000A0000 - 000BFFFF VGA video DRAM, mapped to the Video

Module

000C0000 - 000C7FFF Write-protected DRAM containing

shadowed video BIOS

yes

000C8000 - 000CFFFF SCSI BIOS extension yes

000D0000 - 000DFFFF BIOS Extensions yes

000E0000 - 000FFFFF System BIOS Shadow yes

10000000 - FFF7FFFF ISA Bus (aliased) no

FFF80000 - FFFFFFFF BIOS no

Table 4-2. System Memory Map.

Interrupt Usage

The EPC-100 PC-compatible interrupt usage is as follows:

Interrupt Interrupt Function

IRQ0 System timer (internal PIIX3 connection)

IRQ1 Keyboard controller

IRQ2 Cascade interrupt input (internal PIIX3 connection)

IRQ3 COM B (if enabled)

IRQ4 COM A (if enabled)

IRQ5 unused

IRQ6 Floppy (if enabled)

IRQ7 LPT1 (if enabled)

IRQ8 Real time clock

IRQ9 Watchdog (if enabled)

(cont’d)