Difference between revisions of "ASCII"
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[[Category:Display]] | [[Category:Display]] | ||
| − | '''ASCII''', the '''A'''merican '''S'''tandard '''C'''ode for '''I'''nformation '''I'''nterchange, is a 7-bit character set used in the BBC Micro series. | + | '''ASCII''', the '''A'''merican '''S'''tandard '''C'''ode for |
| + | '''I'''nformation '''I'''nterchange, is a 7-bit character set used in the | ||
| + | BBC Micro series. | ||
| − | It includes a set of control codes for data transmission which were not relevant to the BBC Micro's display and so were reused as <code>[[VDU]]</code> commands. | + | It includes a set of control codes for data transmission which were not |
| + | relevant to the BBC Micro's display and so were reused as | ||
| + | <code>[[VDU]]</code> commands. | ||
| − | The BBC Micro series supports 8-bit characters and so the higher order characters (values 128 to 255) are user definable in all <code>MODE</code>s except <code>MODE 7</code>. | + | The BBC Micro series supports 8-bit characters and so the higher order |
| + | characters (values 128 to 255) are user definable in all <code>MODE</code>s | ||
| + | except <code>MODE 7</code>. RISC OS predefines the set to ISO Latin 1 which | ||
| + | is an 8-bit character set. | ||
| − | There are some differences between standard ASCII and the BBC Micro's two character sets. | + | There are some differences between standard ASCII and the BBC Micro's two |
| + | character sets. In <code>[[MODE]]</code>s 0 to 6 the backtick (`) is | ||
| + | replaced with a pound sign (£) and the vertical bar (|) is broken | ||
| + | (¦). On the other hand <code>[[MODE 7]]</code> is a [[Teletext]] | ||
| + | mode, whose character set is mostly ASCII with a few replaced and relocated | ||
| + | characters. [[OSWRCH]] translates three of the ASCII characters to their | ||
| + | Teletext equivalents before storing them in the <code>MODE 7</code> screen | ||
| + | memory. | ||
| − | In BASIC, <code>[[ASC]]</code> returns the ASCII value of a character. | + | In BASIC, <code>[[ASC]]</code> returns the ASCII value of a character. |
| + | <code>[[CHR$]]</code> creates a character from its ASCII value, and | ||
| + | <code>[[VDU]]</code> prints characters by value. | ||
{| class="wikitable" | {| class="wikitable" | ||
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|- style="text-align:center;vertical-align:top" | |- style="text-align:center;vertical-align:top" | ||
! 06 | ! 06 | ||
| − | | [[VDU 6|ACK]] || [[VDU 22|SYN]] || & | + | | [[VDU 6|ACK]] || [[VDU 22|SYN]] || & || 6 || F || V || f || v |
|- style="text-align:center;vertical-align:top" | |- style="text-align:center;vertical-align:top" | ||
! 07 | ! 07 | ||
| Line 53: | Line 69: | ||
|- style="text-align:center;vertical-align:top" | |- style="text-align:center;vertical-align:top" | ||
! 0C | ! 0C | ||
| − | | [[VDU 12|FF]] || [[VDU 28|FS]] || , || | + | | [[VDU 12|FF]] || [[VDU 28|FS]] || , || < || L || \ || l |
| | | | | | ||
|- style="text-align:center;vertical-align:top" | |- style="text-align:center;vertical-align:top" | ||
| Line 60: | Line 76: | ||
|- style="text-align:center;vertical-align:top" | |- style="text-align:center;vertical-align:top" | ||
! 0E | ! 0E | ||
| − | | [[VDU 14|SO]] || [[VDU 30|RS]] || . || | + | | [[VDU 14|SO]] || [[VDU 30|RS]] || . || > || N || ^ || n || ~ |
|- style="text-align:center;vertical-align:top" | |- style="text-align:center;vertical-align:top" | ||
! 0F | ! 0F | ||
Latest revision as of 16:52, 12 November 2017
ASCII, the American Standard Code for Information Interchange, is a 7-bit character set used in the BBC Micro series.
It includes a set of control codes for data transmission which were not
relevant to the BBC Micro's display and so were reused as
VDU commands.
The BBC Micro series supports 8-bit characters and so the higher order
characters (values 128 to 255) are user definable in all MODEs
except MODE 7. RISC OS predefines the set to ISO Latin 1 which
is an 8-bit character set.
There are some differences between standard ASCII and the BBC Micro's two
character sets. In MODEs 0 to 6 the backtick (`) is
replaced with a pound sign (£) and the vertical bar (|) is broken
(¦). On the other hand MODE 7 is a Teletext
mode, whose character set is mostly ASCII with a few replaced and relocated
characters. OSWRCH translates three of the ASCII characters to their
Teletext equivalents before storing them in the MODE 7 screen
memory.
In BASIC, ASC returns the ASCII value of a character.
CHR$ creates a character from its ASCII value, and
VDU prints characters by value.
| 00 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | |
|---|---|---|---|---|---|---|---|---|
| 00 | NUL | DLE | (Space) | 0 | @ | P | ` | p |
| 01 | SOH | DC1 | ! | 1 | A | Q | a | q |
| 02 | STX | DC2 | " | 2 | B | R | b | r |
| 03 | ETX | DC3 | # | 3 | C | S | c | s |
| 04 | EOT | DC4 | $ | 4 | D | T | d | t |
| 05 | ENQ | NAK | % | 5 | E | U | e | u |
| 06 | ACK | SYN | & | 6 | F | V | f | v |
| 07 | BEL | ETB | ' | 7 | G | W | g | w |
| 08 | BS | CAN | ( | 8 | H | X | h | x |
| 09 | HT | EM | ) | 9 | I | Y | i | y |
| 0A | LF | SUB | * | : | J | Z | j | z |
| 0B | VT | ESC | + | ; | K | [ | k | { |
| 0C | FF | FS | , | < | L | \ | l | | |
| 0D | CR | GS | - | = | M | ] | m | } |
| 0E | SO | RS | . | > | N | ^ | n | ~ |
| 0F | SI | US | / | ? | O | _ | o | DEL |
| ASCII value (hex) | (decimal) | Standard character | In MODES 0 to 6 | In MODE 7 | Teletext value (hex) |
|---|---|---|---|---|---|
| 23 | 35 | # | # | # | 5F |
| 5B | 91 | [ | [ | ← | 5B |
| 5C | 92 | \ | \ | ½ | 5C |
| 5D | 93 | ] | ] | → | 5D |
| 5E | 94 | ^ | ^ | ↑ | 5E |
| 5F | 95 | _ | _ | – | 60 |
| 60 | 96 | ` | £ | £ | 23 |
| 7B | 123 | { | { | ¼ | 7B |
| 7C | 124 | | | ¦ | ‖ | 7C |
| 7D | 125 | } | } | ¾ | 7D |
| 7E | 126 | ~ | ~ | ÷ | 7E |
-- beardo 22:32, 7 November 2007 (UTC)
