Rainbow 100 PC100 System Specification

This document provides a detailed specification for the Digital Equipment Corporation PC100, a low-cost, user-installable personal business computer aimed at the Fortune 1000 market. Designed for users with no prior computer experience, it supports both stand-alone processing and VT102 terminal emulation.

The core system, housed in the BA25 multi-box, features a unique dual-processor architecture comprising an 8088 CPU and a Z80A CPU, which share 62KB of dynamic RAM. The 8088 manages video output, keyboard I/O, printer port, and communications, while the Z80A controls the integral RX50 mini-floppy disk drive. System memory includes 24KB ROM, 4KB static screen/attribute RAM, and 256x4 Non-Volatile Memory (NVM) with shadow RAM for system settings, with options for an additional 64KB or 192KB of unshared dynamic memory. The video subsystem offers VT100-compatible features such as smooth scrolling, double height/width lines, and a 256-character set.

Optional modules enhance the system with expanded memory (up to 256KB total), an extended communications port for high-speed networking, and a bit-mapped color graphics option providing VT240 functionality with various resolutions and a 4096-color palette. The RX50 floppy drive offers 819,200 bytes of formatted storage per device.

The PC100's firmware implements VT102 emulation in "terminal" and "console" modes, offering essential system services like console I/O, cursor control, and self-diagnostics. The document details functional differences from a true VT102, as well as specific "non-goals." The PC100 is designed to comply with numerous environmental, reliability (2800 hours MTBF), and regulatory standards, including FCC Class B for emissions.