SCSI host adapters and firmware mapping: Beyond I/O port addresses, do SCSI adapters also occupy a ROM (BIOS) address range for their onboard firmware?

Introduction / Context:
Expansion cards can include option ROMs that extend BIOS functionality. Classic SCSI host adapters frequently ship with onboard BIOS to support booting from SCSI disks and provide low-level services before the operating system loads. Understanding address space usage helps diagnose resource conflicts and boot issues on legacy systems.

Given Data / Assumptions:

• PC architecture allows plug-in cards to map option ROMs into the system's address space.
• SCSI adapters often include firmware to enumerate and boot from attached devices.
• The question asks whether ROM address ranges are also used, besides I/O ports.

Concept / Approach:
SCSI adapters typically decode I/O ports for command/status and map an option ROM into the C0000h–E0000h shadow region (exact segment varies). The firmware initializes the SCSI bus during POST, exposes INT 13h extensions for disk services, and enables booting from SCSI targets. Therefore, they do use a ROM address range, not just I/O ports and IRQ/DMA resources.

Step-by-Step Solution:

Verification / Alternative check:
During POST, the adapter usually displays its BIOS banner and version. Device Manager on legacy systems shows the option ROM region; motherboard setup may provide “shadow” options for those ranges.

Why Other Options Are Wrong:
False and conditional choices contradict standard behavior across ISA/PCI SCSI adapters; the presence of an option ROM is common whenever boot or BIOS-level services are provided.

Common Pitfalls:
Disabling option ROMs while intending to boot from SCSI, or ROM address conflicts with video BIOS or other adapters.

Final Answer:
True