DWMVA VME Adapter Technical Manual

This document is a technical manual for the DWMVA VME Adapter, an I/O adapter designed to connect a VMEbus to the XMI bus of a VAX 6000 computer system. It is primarily intended for software developers creating drivers and application programs for this adapter.

The manual provides detailed technical descriptions of the DWMVA's hardware operations, its component modules, and bit-level functional descriptions of its registers.

Key areas covered include:

• Major Components: The DWMVA consists of two modules: the T2018 (on the XMI bus) and the C3200 (on the VMEbus), communicating via an internal IBUS.
• Bus Interfacing & Address Mapping: How the adapter bridges the synchronous XMI bus with the asynchronous VMEbus, including the translation of addresses between the different addressing schemes (XMI to VME for CPU transactions, VME to XMI for DMA transactions) and various VAX address translation modes (34-bit, 40-bit with different page sizes).
• Transactions: The two main types of transactions processed: CPU-initiated (reading/writing to VME devices or DWMVA registers) and VME-initiated DMA (reading/writing to XMI memory). It covers command translation and interlock handling.
• VME System Control: The C3200 module acts as the VME system controller, managing VMEbus arbitration (supporting round robin, prioritized, and single-level algorithms), bus timing, IACK daisy-chain driving, and clock signals.
• Interrupts: Details the VME-to-XMI interrupt protocol, including error interrupts generated by the DWMVA and how interrupt requests are handled and translated to XMI interrupt priority levels.
• Registers: Comprehensive, bit-level descriptions of all control, status, and error registers residing on both the T2018 and C3200 modules.
• Initialization: Procedures for initializing the DWMVA subsystem.
• Byte Swapping: An in-depth explanation of how the DWMVA handles byte order differences (endianness) between the VMEbus and XMI, with various configurable swapping modes.