Browse Prior Art Database

Device independent graphical display description (RFC0177)

IP.com Disclosure Number: IPCOM000004021D
Original Publication Date: 1971-Jun-15
Included in the Prior Art Database: 2000-Sep-12
Document File: 7 page(s) / 19K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. McConnell: AUTHOR

Abstract

As more nodes are connected to the ARPA network, the types of graphical display processors available to users is quite varied. To attempt to facilitate the transmission of graphical information over the network, a device independent description of a display is described. The using host may make any conversions necessary to realize the picture on a specific device. It is also possible to interpose a form machine as proposed by Heafner and Harslem in RFC #94. Some of the items and entities described herein were first discussed by Steve Crocker in RFC #86. It is intended that this description is to be oriented to a refresh display with point, vector, and character drawing capability, these types of devices include the IBM 2250, IMLAC PDS-1, the DEC 338, and DEC 340, as well as the Evans and Sutherland LDS-1. However, direct video storage tube devices represented by the ARDS, Tektronix and Computer devices can also serve as clumsy interactive devices. Hard copy devices, such as microfilm or plotters, can also be used at the using host's discretion.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 15% of the total text.

NETWORK WORKING GROUP J. McConnell

Request for Comment: 177 Ames Research Center Moffet Field, CA

Obsoletes: none 15 June 1971

Updates: 125

NIC: 7102

A DEVICE INDEPENDENT GRAPHICAL DISPLAY DESCRIPTION

As more nodes are connected to the ARPA network, the types of

graphical display processors available to users is quite varied. To

attempt to facilitate the transmission of graphical information over

the network, a device independent description of a display is

described. The using host may make any conversions necessary to

realize the picture on a specific device. It is also possible to

interpose a form machine as proposed by Heafner and Harslem in RFC

#94. Some of the items and entities described herein were first

discussed by Steve Crocker in RFC #86. It is intended that this

description is to be oriented to a refresh display with point,

vector, and character drawing capability, these types of devices

include the IBM 2250, IMLAC PDS-1, the DEC 338, and DEC 340, as well

as the Evans and Sutherland LDS-1. However, direct video storage

tube devices represented by the ARDS, Tektronix and Computer devices

can also serve as clumsy interactive devices. Hard copy devices,

such as microfilm or plotters, can also be used at the using host's

discretion.

There are several items and constructs which will be defined before

discussing the specifics of the description:

1. The network standard graphics description stream (NGDS)

contains the description, data, and operators necessary to effect

a display.

2. The network standard stream interpreter (NGSI) parses the NGDS

into its components.

3. The network standard display list (NGDL) is the basic entity

which, when executed, causes graphical information to be

displayed.

4. The network standard list interpreter (NGLI) is the entity

which executes the NGDL and controls the beam movement to effect

generation of graphical information.

5. The network standard screen (NGS) is the entity on which the

information is to be displayed. It may be divided into image

areas to be defined later.

6. The network standard graphics list pointer (NGLP) and the

network standard graphics execution stack (NGES) are entities

which describe the state of the NGLI at any given time and provide

the facilities to allow the NGLI to be a recursive interpreter.

Figure 1. summarizes the preceding discussion graphically, which is

appropriate.

The network standard graphics screen is rectangular and positions on

it are specified by an ordered pair of fractions representing the

horizontal distance from the left edge and the vertical distance from

the bottom edges respectively. These shall be termed the (x,y)

coordinates as is standard. There is no specification of resolution,

so that the quality of ...