Browse Prior Art Database

Subroutine Means for Dynamic DTV

IP.com Disclosure Number: IPCOM000088077D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 6 page(s) / 142K

Publishing Venue

IBM

Related People

Holderness, CJ: AUTHOR [+2]

Abstract

On-the-fly digital television (DTV) systems have, in the past, required that each item (line, symbol, conic, etc.) which appears on the screen be stored in the refresh buffer once for each occurrence as in U. S. Patent 3,996,585. In some display applications, however, groups of lines and symbols are combined into patterns which are repeated in several places on the screen. Examples of such applications might be utility mapping and graphic design. The ability to store such a pattern (graphic entity) only once in refresh memory and invoke it as required on the display offers several advantages: Refresh storage is conserved. Modification to the graphic entity in one place in the refresh buffer will cause the pattern to be changed wherever it is invoked on the display.

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Subroutine Means for Dynamic DTV

On-the-fly digital television (DTV) systems have, in the past, required that each item (line, symbol, conic, etc.) which appears on the screen be stored in the refresh buffer once for each occurrence as in U. S. Patent 3,996,585. In some display applications, however, groups of lines and symbols are combined into patterns which are repeated in several places on the screen. Examples of such applications might be utility mapping and graphic design. The ability to store such a pattern (graphic entity) only once in refresh memory and invoke it as required on the display offers several advantages: Refresh storage is conserved. Modification to the graphic entity in one place in the refresh buffer will cause the pattern to be changed wherever it is invoked on the display. Complex patterns consisting of many separate items can be moved on the display by changing the position of only one refresh point. Blink control over graphic entities as a whole is facilitated.

The present article describes a means of adding this capability to dynamic DTV (DDTV). In the discussion which follows, it will be assumed that the reader is familiar with U. S. Patent 3,996,585, and only the required changes to DDTV will be discussed in any detail.

In the present approach, subroutine capability is added to DDTV through modification to the Refresh Buffer (RB), the Intermediate Buffer (IB), the data formats, and the preprocessing by the Programmable controller of U. S. Patent 3,996,585. Specifically, a new RB format, called the Indirect Pointer (IP), is added. In addition, provision is made for using the Vector and Symbol Formats in a different way and for adding an extra field to each slot. A new intermediate buffer, called the Indirect Intermediate Buffer (IIB) is added, as are certain other arithmetic and control functions. The new organization is shown in Fig. 1. Note that the subdivision of the refresh buffer is arbitrary. IPs and conventional DDTY data can be intermixed and threaded together in the same strings pointed to by the same index registers. All data slots can be used for conventional DDTV or subroutine graphic entity data. However, since subroutine slots involve an extra word a permanent, but programmable, partition is desirable. It may be possible to partition dynamically, but this is not essential. Failing this, two threads of empty slots are used, one for normal DDTV refresh buffer use and one for subroutine use by the Programmable Controller.

It is necessary to modify the Vector Format of U. S. Patent 3,996,585 to accommodate the new IP format. The revised vector format and the new IP format are shown in Fig. 2.

If bit 2 indicates that the slot is not a Symbol Format, bit 4 is examined to determine if it is a Vector or an IP.

The IP contains the desired X position of the topmost item in the pattern to be displayed (y is implied by the index), and a pointer to the topmost item in the graphic entity, as well as th...