Display Focal

This document describes 'Display Focal' (DECUS No. FOCAL8-187), a program intended for 4K PDP-8 systems equipped with a VT01 storage display and a KV8/I controller. It provides two routines:

• FADC: An analogue to digital converter routine used to clear the screen.
• FNEW: The main plotting routine that operates in vector mode, allowing for absolute plotting of points, short/long vectors, and visible/invisible vectors.

The document includes loading instructions for both disk/DECtape systems and non-system device configurations, as well as operational details on interrupt-driven plotting and screen clearing. It also provides a source code listing for the patch and memory mapping information.