KW11-K Dual Programmable Real Time Clock User Manual

This document is the user manual for the Digital Equipment Corporation (DEC) KW11-K, a dual programmable real-time clock option designed for PDP-11 Unibus computers.

Key features and functionalities described include:

• Dual Clocks: It incorporates two independent programmable clocks:

  • Clock A: A 16-bit counter with a 16-bit Preset/Buffer register, supporting four modes of operation (Single Interval, Repeated Interval, External Event Timing from current count, and External Event Timing from zero base). It offers eight selectable clock rates, including five crystal-controlled frequencies (1 MHz to 100 Hz), an external input (Schmitt Trigger One), line frequency, or the overflow of Clock B. It can generate interrupts and external events.
  • Clock B: An 8-bit counter with an 8-bit Preset register, primarily operating in a repeated interval mode. It provides seven selectable clock rates, including five crystal-controlled frequencies, an external input (Schmitt Trigger Three), or line frequency. It can also generate interrupts and external events and its overflow can serve as a clock source for Clock A (Feed B to A mode).

• Schmitt Triggers: Three Schmitt Trigger inputs (ST1, ST2, ST3) are provided, offering threshold and slope control for external event synchronization, such as starting counters or loading buffer registers.

• Auto-Incrementing: A specific mode for Clock A (in conjunction with ST1) that allows the clock's preset value to decrement automatically, enabling high-frequency waveform sampling, particularly for A/D converter applications.
• Physical and Interfacing: The KW11-K is a single M7025 hex module, requiring +5 Vdc power. Its register and vector addresses are configurable via switches and solder jumpers, and it includes an I/O connector (H854) for external signals.
• Programming Details: The manual outlines the functionality of the A and B Status Registers, Counter Registers, and Preset/Buffer Registers, explaining their bits and how to program them to control clock operations, modes, rates, and interrupt generation.