Browse Prior Art Database

Graphic Interface

IP.com Disclosure Number: IPCOM000050942D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 4 page(s) / 35K

Publishing Venue

IBM

Related People

DeOrazio, WR: AUTHOR [+5]

Abstract

The Research Graphics Interface (REGI) card permits the attachment of Tektronix 4015 and 4013 graphics terminals to the IBM 3277 Graphics Attachment RPQ (GA). With the card installed, the Tektronix terminals may be used as either a Tektronix 618/619 substitute or a fully functional 4015/ 4013 terminal.

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Graphic Interface

The Research Graphics Interface (REGI) card permits the attachment of Tektronix 4015 and 4013 graphics terminals to the IBM 3277 Graphics Attachment RPQ (GA). With the card installed, the Tektronix terminals may be used as either a Tektronix 618/619 substitute or a fully functional 4015/ 4013 terminal.

The REGI card interfaces to a Tektronix 4015/ 4013 through the terminal's minibus and to a GA through a special cable. All analog and digital signals presented by the CA are supported through the interface.

IBM 3277 Graphics Attachment Control Lines

All control lines from the 3277 GA are terminated on the REGI card, as shown in Fig. 1. In this manner, the control lines are prevented from going to an active level when the interface cable is removed from the REGI card.

The GA control lines are isolated from the Tektronix terminal's minibus by means of a non-inverting, open collector hex buffer.

Terminal/Graphic Operations.

When the TERM/GRAPH switch is placed in the TERM position, a negative signal is applied to the input of single-shot 1, (SS1), as shown in Fig. 2. SS1 triggers a negative pulse to the latch coil of the analog and Z-axis relays, placing the terminal in normal 4015/ 4013 graphics terminal operation. When in this mode, the REGI logic is not used.

In the TERM mode, the X- and Y-analog signals are taken from the 4015's or 4013's minibus and sent directly to the 4015/ 4013 display. In the 4013, the Z- axis is also taken from the minibus. However, in the 4015, the Z-axis is taken from the 4015's Terminal Control Card, hence the need for the two-foot jumper cable. In both cases, the Z-axis signals are sent directly to the 4015/4013 display.

When the TERM/GRAPH switch is placed in the GRAPH position, a negative signal is applied to single-shot 2 (SS2). SS2 triggers a negative pulse to the unlatch coils of the analog and Z-axis relays, placing the terminal in graphics operations. When in this mode, the REGI logic is enabled.

In GRAPH mode, the REGI logic drives the 4015/ 4013 display. This is explained in greater detail further in this section.

The duration of the single-shots is longer than the settling time of the switch; therefore, anti-bounce circuits are not required.

The relays controlled by these single-shots are mechanical and only have to be pulsed to latch or unlatch. With this type of relay, no continuous current is drawn from the +5 volt power supply in the Tektronix terminal.

Write-Thru Mode.

1

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When the GA's WRITE THRU control line goes negative, it is inverted and a positive signal is applied to input L1 of SS1, as shown in Fig.
3. Since input L2 is the Q output of SS1, L2 is negative. A negative L2 and a positive L1 meets the input condition of the single-shot and SS1 fires a 300-nanosecond negative pulse on the -Q output and a positive pulse on the Q output. When SS1 times out, L2 goes negative and, if L1 is still positive, SS1 will fire again.

This will continue until WRITE THRU g...