Compact portable alphanumeric display device can be used with any general-purpose externally-triggered oscilloscope without need for Z-axis modulation. Factors limiting size of display are: output line capacitance, read-only memory speed, and persistence of cathode-ray-tube

Boston, R. E.

Lockerson, D. C.

English

NASA Technical Reports Server

I	 Blanking	 I 
Block Diagram of Basic Character Generator
Buffer	 L41,. To Scope 
I	 Vertical 
To Scope 
Trigger 
October 1973 
•	 NASA TECH BRIEF 
Goddard Space Flight Center
B73-10370 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Alphanumeric Character Generator for Oscilloscope 
The problem: 
Printers and cathode-ray-tube (CRT) display terminals 
have been the most popular devices for presenting 
systems data. They are expensive, limited in application 
from model to model, and not truly portable. 
The solution: 
A compact portable alphanumeric character-display 
device can be used with any general-purpose externally. 
triggered oscilloscope without need for Z-axis modula-
tion.
How it's done: 
The figure shows the character generator in block 
diagram. The generator pulses the oscilloscope external 
trigger, initiating a horizontal sweep of the scope trace. 
If no character segment is to be displayed, the vertical 
signal is inhibited by the clamping switch. When a 
segment is to be displayed, a pulse is generated in the 
desired position on the oscilloscope in the form of a 
short dash (segment). The vertical position of this 
segment is determined by the state of the ladder 
network. The alphanumeric characters are thus formed 
S Data Input 
Data Transfer 
Clock 
IDlnputs —.	 • 
Is. 
- 
Space 
dICh.:,acter 
lloscoe 
From 
Countdown 
I
I...'
Data
Registers 
Data
Identification
Commutators
G (8 Characters/Line) N3 
S (Groups of Two) N2 
N1 
Countdown 
Chain
85 CH-FR 45 N 1 N 2 N 3	 F	 2S 
I	 Ladder	 I
A 
A2 Character- 
A3 Select 
A4
j
Inputs 
5 Read-
Only 
Memory 
(ROM)
A 
A 
A8 D 1 D 2 D 3 D 4 D 5 D 6 D 7 D 8 
Ui	 Parallel/ 
Serial 
Converter 
(continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behall of the United States
	 will be free from privately owned rights. 
https://ntrs.nasa.gov/search.jsp?R=19730000370 2020-03-17T07:05:06+00:00Z
on the oscilloscope faceplate by the quantity and 
arrangement of these short dashes (segments). A read-
only memory (ROM) contains the microprogram used 
to determine whether a segment is to be displayed or 
inhibited. 
Factors that limit the size of the display are: output 
line capacitance, ROM speed, and persistence of the 
CRT. Capacitance must be kept to a minimum, because 
the output must switch very rapidly between the clamp-
ing voltage and the segment levels, in order to avoid 
annoying flicker. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Goddard Space Flight Center 
Code 207.1 
Greenbelt, Maryland 20771 
Reference: B73-10370
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Inquiries concerning non-
exclusive or exclusive license for its commercial develop-
ment should be addressed to: 
Patent Counsel 
Goddard Space Flight Center 
Code 204 
Greenbelt, Maryland 20771 
Source: Donald C. Lokerson and

Ronald E. Boston
Goddard Space Flight Center

(GSC-1 1582)
is 
B73-10370	 Category 02


Alphanumeric character generator for oscilloscope

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server