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terminal_ascii

ASCII Terminal

This probably does not need to be defined, however, for completeness ~ I have decided to document the ASCII character set supported by both the BBS and the terminal (and almost all terminals).

DECIMAL HEX MEANING
0 0x00 No Operation (some UTF8 sequences end with null).
1 0x01 SOH Start of Header (XModem Block Header)
2 0x02 STX Start of Text (1k XModem/YModem Block Header)
3 0x03 ETX End of Text
4 0x04 EOT End of Transmission
5 0x05 ENQ Enquiry (Can be used to query User Name)
6 0x06 ACK Acknowledge
7 0x07 BELL Beep on my Terminals
8 0x08 BS Backspace (usually non-destructive)
9 0x09 TAB Horizontal Tabulation
10 0x0A LF Line need (Cursor just moved down 1 line)
11 0x0B VT Vertical Tabulation
12 0x0C NF or NP New Form, New Page (old way to clear screen)
13 0x0D CR Carriage Return (Home cursor on current line)
14 0x0E SO Shift Out
15 0x0F SI Shift In
16 0x10 DLE Data Link Exchange
17 0x11 DC1 Data Control 1
18 0x12 DC2 Data Control 2
19 0x13 DC3 Data Control 3
20 0x14 DC4 Data Control 4
21 0x15 NAK Negative Acknowledge
22 0x16 SYN Synchronous Idle
23 0x17 ETB End of Transmission Block
24 0x18 CAN Cancel (Abort YModem Transfer)
25 0x19 EM End of Medium
26 0x1A SUB Substitute
27 0x1B ESC Escape Key
28 0x1C FS File Separator
29 0x1D GS Group Separator
30 0x1E RS Record Separator
31 0x1F US Unit Separator

From this point (Character 32, which is your spacebar) to (Character 126, which is the ~ Tilde key) are represented in human readable character on the screen. Some terminals and operating systems use Character 127 (DEL) as their backspace character ~ our BBS and terminal understand this and handle it appropriately.

Pressing Enter

Most systems will send the sequence 0x0A 0x0D (CRLF) when you press Enter. However, some of the older operating systems used still to this date for BBSes only expect the terminal to send 0x0A when you press Enter. Most modern terminals do not treat CR and LF independently, and will have to go through some effort to simulate a different output. When a modern terminal does have the ability to modify this, they will send CR NUL 0x0A 0x00 ~ out BBS and terminal understand this and handle it appropriately. 1)

1)
RFC854 May 1983
terminal_ascii.txt · Last modified: 12/15/2019 04:59 by Ozz Nixon