6530 Programmer's Guide

Overview
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6530 Programmer’s Guide
Character Codes The 6530 can be configured to transmit either 7-bit or 8-bit character
codes, with or without parity. The lower 7 bits are used for the standard
ASCII character set, which represents 128 different characters. The
eighth bit is used for an upper 128-character set, which is the same as the
workstation’s or PC’s standard alternate character set.
Both the 7-bit and 8-bit codes represent two types of characters:
Control characters
Graphics (displayable) characters
With the 7-bit ASCII codes, control characters are represented in the
range of 00H to 1FH. This is referred to as the C0 set. Graphics
characters are represented in the range of 20H to 7FH, referred to as the
G0 set.
The 8-bit codes include the C0, G0, C1, and G1 sets. The C1 set is
another set of control characters, represented in the range of 80H to 9FH.
The G1 set is an additional set of graphic characters, represented in the
range of A0H to FFH. Table 1-1 summarizes the character set ranges.
The graphics characters consist of alphanumeric and special symbols,
such as punctuation marks. When the 6530 receives a graphics character
code, it stores the specified character in display memory at the current
cursor or buffer address and increments the address by one position.
Your application program can send graphics code in the G0 set simply by
sending the ASCII character. If the 6530 is configured for 8 bits, you can
also send graphics codes in the G1 set by sending the 8-bit character
code. If the 6530 is configured for 7 bits, you can send graphics codes in
the G1 set by first sending an SO (shift out) control character to shift to
the G1 set and then sending the corresponding ASCII character. The SI
(shift in) control character shifts back to the G0 set. The SO
and SI control characters can also be used in 8-bit configurations.
Appendix A lists the graphics characters in the G0 set, along with their
corresponding ASCII codes. For characters in the G1 set, see your
workstation or PC documentation.
Table 1-1. Character Set Ranges
Set Range Description
C0 00H to 1FH ASCII control characters
G0 20H to 7FH ASCII graphics characters
C1 80H to 9FH Upper (alternate) control characters
G1 A0H to FFH Upper (alternate) graphics characters