Foenix F256 / Wildbits/K2 Wiki - User contributions [en]

FNX6809 DisplayCodes

2026-04-28T18:55:46Z

RichL: /* remove Escape Codes */

= Wildbits VTIO Driver Control Sequences =

This document describes the control character sequences supported by the <code>vtio.asm</code> video terminal I/O driver for the Wildbits platform.

== Basic Control Characters (0x00 - 0x0D) ==

These single-byte commands perform basic cursor and screen operations.

{| class="wikitable"
! Hex Code !! Command !! Description
|-
| <code>0x01</code> || '''Home Cursor''' || Moves the cursor to the top-left corner (0,0).
|-
| <code>0x02</code> || '''Move Cursor (XY)''' || Positions the cursor at (X, Y). Followed by two bytes: <code>X + 32</code> and <code>Y + 32</code>. (See "Coordinate Offset" below).
|-
| <code>0x03</code> || '''Erase Line''' || Clears the entire current line.
|-
| <code>0x04</code> || '''Erase to EOL''' || Clears the line from the current cursor position to the end.
|-
| <code>0x05</code> || '''Cursor Control''' || Sub-command for cursor state. Followed by a mode byte (see below).
|-
| <code>0x06</code> || '''Cursor Right''' || Moves the cursor one position to the right.
|-
| <code>0x07</code> || '''Bell''' || Sounds the system bell.
|-
| <code>0x08</code> || '''Cursor Left''' || Moves the cursor left and erases the character previously at that position (Backspace).
|-
| <code>0x09</code> || '''Cursor Up''' || Moves the cursor one line up.
|-
| <code>0x0A</code> || '''Cursor Down''' || Moves the cursor one line down.
|-
| <code>0x0B</code> || '''Erase to EOS''' || Clears the screen from the cursor position to the end.
|-
| <code>0x0C</code> || '''Clear Screen''' || Clears the entire screen and homes the cursor.
|-
| <code>0x0D</code> || '''Carriage Return''' || Moves the cursor to the beginning of the current line (column 0).
|}

=== Coordinate Offset (+32) ===
The '''Move Cursor (XY)''' command (<code>0x02</code>) requires coordinates to be offset by '''32''' (0x20). This is a standard OS-9 convention used to shift coordinate values out of the range of ASCII control characters (0x00–0x1F), ensuring they are treated as data rather than unintended commands.
* '''To move to Column 0:''' Send <code>0 + 32 = 32</code> (<code>0x20</code>).
* '''To move to Column 10:''' Send <code>10 + 32 = 42</code> (<code>0x2A</code>).
* '''Internal Math:''' The driver performs <code>InternalCoord = Argument - 0x20</code>.

=== Cursor Control (0x05) Sub-commands ===

{| class="wikitable"
! Sequence !! Command !! Description
|-
| <code>0x05 0x20</code> || '''Cursor Off''' || Hides the video cursor.
|-
| <code>0x05 0x21</code> || '''Cursor On''' || Shows the video cursor.
|-
| <code>0x05 0x22 <CHR></code> || '''Cursor Char''' || Changes the cursor character to the provided byte <code><CHR></code>.
|-
| <code>0x05 0x23 <RATE></code> || '''Cursor Rate''' || Changes flash rate: <code>0</code>=1s, <code>1</code>=0.5s, <code>2</code>=0.25s, <code>3</code>=0.2s, <code>4</code>=Disabled.
|}

----

== Escape Sequences (0x1B) ==

Extended commands typically used for windowing and palette management.

{| class="wikitable"
! Sequence !! Command !! Description !! Arguments
|-
| <code>0x1B 0x20</code> || '''Set Window''' || Configures screen mode and dimensions. || <code>STY</code>, <code>CPX</code>, <code>CPY</code>, <code>SZX</code>, <code>SZY</code>, <code>FG</code>, <code>BG</code>, <code>BD</code> (See below)
|-
| <code>0x1B 0x32</code> || '''Fore Color''' || Sets the current foreground color. || <code><COLOR></code> (1 byte)
|-
| <code>0x1B 0x33</code> || '''Back Color''' || Sets the current background color. || <code><COLOR></code> (1 byte)
|-
| <code>0x1B 0x34</code> || '''Border Color''' || Sets the current border color. || <code><COLOR></code> (1 byte)
|-
| <code>0x1B 0x60</code> || '''Fore Palette''' || Modifies a foreground palette entry. || <code>PRN</code>, <code>R</code>, <code>G</code>, <code>B</code>, <code>A</code> (See below)
|-
| <code>0x1B 0x61</code> || '''Back Palette''' || Modifies a background palette entry. || <code>PRN</code>, <code>R</code>, <code>G</code>, <code>B</code>, <code>A</code> (See below)
|-
| <code>0x1B 0x62</code> || '''Font Set 0''' || Switches to font set 0. || None
|-
| <code>0x1B 0x63</code> || '''Font Set 1''' || Switches to font set 1. || None
|}

=== Set Window (1B 20) Parameters ===
The command requires 8 parameter bytes following the header:

* '''STY (Screen Type):'''
** <code>1</code>: 40x30 Text
** <code>2</code>: 80x30 Text
** <code>3</code>: 40x60 Text
** <code>4</code>: 80x60 Text
* '''CPX (Starting X):''' The starting column (0–79). ''Note: Currently ignored for anchor point; windows always start at (0,0).''
* '''CPY (Starting Y):''' The starting row (0–59). ''Note: Currently ignored for anchor point.''
* '''SZX (Width):''' The width of the window in columns.
* '''SZY (Height):''' The height of the window in rows.
* '''FG (Foreground):''' Default foreground color index (0–15).
* '''BG (Background):''' Default background color index (0–15).
* '''BD (Border):''' Border color index (0–15).

''Note: Executing this command clears the screen to the specified background color.''

=== Palette Modification Parameters (1B 60 / 1B 61) ===
These commands require 5 parameter bytes following the header:

* '''PRN (Palette Register Number):''' The index of the palette register to modify (<code>0</code> to <code>15</code>).
* '''R, G, B:''' Red, Green, and Blue intensity values (<code>0</code> to <code>255</code>).
* '''A (Alpha):''' Opacity/Alpha value (<code>0</code> to <code>255</code>).

----

== Miscellaneous Sequences ==

{| class="wikitable"
! Sequence !! Command !! Description
|-
| <code>0x1C <CHR></code> || '''Raw Write''' || Writes the next byte <code><CHR></code> directly to the screen (bypasses control checks).
|-
| <code>0x1F 0x20</code> || '''Reverse On''' || Enables reverse video (swaps FG and BG colors).
|-
| <code>0x1F 0x21</code> || '''Reverse Off''' || Disables reverse video.
|}

''Note: Characters 0x0E-0x1A, 0x1D, and 0x1E are currently processed as No-Ops by the driver.''

----

== Example Interpretation ==

'''Sequence:''' <code>1b 61 01 ff 00 00 ff 05 22 f0 1b 20 02 00 00 50 18 00 01 00 1b 32 07</code>

This string performs the following operations in order:

# '''<code>1b 61 01 ff 00 00 ff</code>''': Modifies Background Palette register '''1''' to be solid '''Red''' (<code>RGBA: 255, 0, 0, 255</code>).
# '''<code>05 22 f0</code>''': Changes the hardware cursor character to <code>0xF0</code>.
# '''<code>1b 20 02 00 00 50 18 00 01 00</code>''': Sets an '''80x24''' window in '''80x30''' text mode starting at <code>(0,0)</code>. It sets the default foreground to color <code>0</code>, the background to color <code>1</code> (Red), and the border to color <code>0</code>. This operation also clears the screen to Red.
# '''<code>1b 32 07</code>''': Sets the current foreground drawing color to index '''7'''.

'''Result:''' The display switches to an 80-column mode with a red background, a custom block cursor, and text subsequently written will appear in color index 7.

----

== Technical Note: Scrolling and Windowing Limitations ==

The current version of the <code>vtio.asm</code> driver has the following limitations regarding windowing:

# '''Anchor Point:''' While <code>Set Window</code> (<code>1B 20</code>) accepts <code>CPX</code> and <code>CPY</code> (starting coordinates), the driver's internal coordinate math and the <code>SCROLL</code> routine currently ignore these offsets. All windows are physically anchored at the top-left (0,0) of the screen.
# '''Global Scrolling:''' The scroll routine (<code>SCROLL</code>) always moves data starting from the very top of the physical screen buffer. Consequently, it is not possible to define a "static" area (like a Z-machine status line) that remains unaffected by scrolling text below it using the native driver logic alone.
# '''Unimplemented Codes:''' Documentation/comments in the source suggest codes <code>1F 30</code> (Insert Line) and <code>1F 31</code> (Delete Line) may have been planned, but they are not currently implemented in the dispatch table.

FNX6809 DisplayCodes

2026-04-28T18:53:33Z

RichL: This is a substantial edit based on the latest vtio.asm file. AI was used to expand on the prior content.