Drivers Module

The Drivers/ directory contains the low-level software that controls the Macintosh hardware. These drivers provide a standard interface for the OS and Toolbox to interact with devices.

Driver Structure

Macintosh drivers typically follow a standard structure:

• Open: Initialize the driver/device.
• Close: Shut down the driver.
• Control: Send commands to the device.
• Status: Get information from the device.
• Prime: Perform I/O operations (Read/Write).

Key Drivers

1. Sony (Drivers/Sony/)

The driver for the 3.5” Floppy Disk Drive.

• Role: Handles raw track reading/writing, GCR encoding/decoding.
• Importance: Often the primary boot device.

2. Video (Drivers/Video/)

Manages the frame buffer and display hardware.

• Role: Sets video modes, handles vertical blanking interrupts (VBL).

3. IOP (Drivers/IOP/)

Support for I/O Processors found in machines like the Mac IIfx and Quadra 900/950.

• Role: Offloads I/O tasks from the main CPU.

4. EDisk (Drivers/EDisk/)

Likely an emulator or RAM disk driver used for testing or specific boot scenarios.

Interfaces

Drivers interact with the system via:

• Device Manager: The OS component that loads and manages drivers.
• Interrupts: Drivers install Interrupt Service Routines (ISRs) to handle hardware events asynchronously.

Configuration

Driver configuration is often hardcoded or determined at runtime by the SlotMgr (for NuBus cards) or StartMgr (for built-in devices).