RL8A

This document outlines the programming interface for the RL8A disk controller, which is used with PDP-8 computer systems. It covers the following key areas:

• General Description: Provides an overview of the M8433 module, which interfaces with OMNIBUS and supports up to four RL01/RL02 disk drives.
• Instruction Set: Details the IOT instructions used to communicate with the controller's six addressable registers.
• Addressable Registers: Describes the function and bit layout of various registers including Command Register A, Command Register B, Break Memory Address, Word Count, Sector Address, and the Error Register.
• Controller Commands: Explains the eight supported operations, such as Maintenance, Reset, Get Status, Seek, Read Header, Write Data, Read Data, and Read Data Without Header Check.
• Operational Considerations: Discusses the 8-bit versus 12-bit operating modes, error recovery procedures, and how to handle specific controller errors.
• Configuration: Contains appendix information regarding RL11 configuration and installation, including SPC considerations.