Full Page Overlay Technique for Half Indexing and Overstrike
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
This article describes a half-indexing and overstrike feature of a baseline character generator that achieves functions such as equation writing. The baseline character generator generates a raster image of a page from a memory that contains a coded and ordered representation of the page. The design enables the printing of two independent pages by electronically overlaying them. Shifting one page a half line offset from the other page is one method of obtaining the half-indexing function. The hardware formats each page alternating one scan or one pair of scans at a time. The scans are alternately fetched, and 'ORed' in the scan buffer-printer interface to get the electronic page overlay.