Kw12 Real Time Clock

This document serves as a technical seminar guide for the KW12 Real Time Clock, a flexible tool designed for use with the PDP-12 computer. The clock features a variable time base (with crystal-controlled accuracy of 0.01% at 400 kHz) and a 12-bit counter that can be incremented by program-selected pulses or external events.

Key Features and Functions:

• Counter and Overflow: The 12-bit counter registers time or event counts and can trigger a program-detectable overflow flag.
• Buffer/Preset Register: This register allows the user to read the counter's contents into the accumulator (AC) or initialize the counter to a specific starting value to determine overflow intervals.
• Input Synchronizers: The device includes three input channels with Schmitt triggers, allowing for the selection of signal voltage thresholds and positive or negative slopes to convert real-world events into program-detectable signals.
• Program Control: Operation is managed via three registers (Clock Control, Clock Enable, and Clock Status). Programmers can select counting rates, modes (such as Free Running, Event Timing, or A/D conversion), and enable specific interrupts.

The document also details a subroutine setup package (KW12SUB) designed to initialize the clock and manage interrupts, including specific calling sequences and programming examples for tasks like periodic Teletype alerts or event counting.

Note: The provided PDF also contains documentation for a separate program, "FRQANA" (or DFRQANA), which is a frequency analysis tool for the PDP-12 that performs sine, cosine, and RMS spectral analysis on data retrieved from LINCtape.