Nop; Ascii Character Codes - HP 7470A Interfacing And Programming Manual

The N0 Operation Instructions, NOP
In order to maintain software compatibility with the 9872 plotter, the
7470 recognizes six 9872—related instructions as no operation NOP in­
structions. These six NOP instructions are:
Automatic Pen Pickup AP Advance Full Page AF
Adaptive Velocity VA Advance Half Page AH
Normal Velocity VN Enable Cutter EC
If these instructions are included in a program, they are recognized by
the 7470 and implemented as a NOP (i.e., they are ignored).
On a 7470plotter with an HP-IL interface, UC is also a NOP instruction.
ASCII Character Codes
Binary is often used as a code to represent not only numbers, but also
alphanumeric characters such as "A" or "," or "x" or "2". One of the
most common binary codes used is ASCII1. ASCII is an eight-bit code,
containing seven data bits and one parity bit. The plotter uses ASCII
for most I/O operations. No parity bit is used. For example:
ASCII ASCII
Character Binary Code Decimal Code
A 01000001 65
B 01000010 66
7 001 1 1 1 1 1 63
A complete list of ASCII characters and their decimal representation
and the characters drawn by the plotter in each of the five character
sets are shown on the following pages. The five character sets are:
Set N0. Description
Set 0 ANSI ASCII
Set 1 9825 Character Set
Set 2 French/ German
Set 3 Scandinavian
Set 4 Spanish/ Latin American
1American Standard Code for Information Interchange.
REFERENCE MATERIAL C-7