Firefox Workstation I/0O Module Functional Specification

This document is the functional specification for the Firefox Workstation I/O Module (L2003), a single L-series-quad module designed for Firefox SMP systems. It integrates all workstation I/O and essential support functions.

Key functionalities and features include:

• Time & Memory: A VAX SRM-compatible Time-of-Year Clock with battery backup, Interval Timers, 1 Kbyte of Battery-Backed-Up RAM for configuration, and 256 Kbytes of Base Workstation ROM.

• External Interfaces:

  • Four Asynchronous Serial Lines: For keyboard, mouse/tablet, modem, and printer/console, compatible with DZ-type interfaces and RS-423 electrical specifications.
  • Disk/Tape Interface: Supports RF/TF series drives using the DSSI architecture, capable of 4 Mbytes/sec data transfers. It includes a local 128-Kbyte RAM buffer (not parity protected).
  • Network Interface: Compatible with DIGITAL ThickWire Ethernet (10 Mbits/sec), also featuring a local 128-Kbyte RAM network buffer (not parity protected) and a fixed 48-bit station address in ROM.

• Control & Status: An I/O Control and Status Register (IOCSR) for workstation reinitialization, M-bus MCLKI signal control, front-panel system indicators, and console mode. It also supports 5-bit status indicator outputs and 2-bit manufacturing-mode inputs.

• M-Bus Interface: Utilizes a Firefox Bus Interface Chip (FBIC) to enable M-bus access to all internal L2003 devices and memory. It acts as a vectored interrupt controller for the serial, disk/tape, and network interfaces, and generates the M-bus MRESET signal.
• Implementation: These functions are largely realized through various VLSI chips (e.g., System Support Chip (SSC), DC7085, SII, LANCE, FBIC).
• Programming Considerations: Software must initialize the FBIC and other devices after reset, calculate device addresses based on the module's M-bus slot, and manage device interrupts (disabling/reenabling is crucial). Interlocked memory references to L2003 internal device registers or RAM buffers are explicitly not supported and will cause bus errors. For systems with multiple L2003 modules, software must designate one as the primary for certain functions (like driving MCLKI).

The L2003 requires a separate cover assembly for physical connectors (serial, Ethernet, DSSI) and display elements.