QDOS Internals

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====== SD_FOUNT/IOW_FONT ======
This trap sets the font for a window.

^Call Parameters^^Return Parameters^^
|D0.B|$25|D0.L|Error code.|
|D1.L|Unused.|D1.L|Corrupted.|
|D2.L|0 or "DEFF"|D2.L|Preserved.|
|D3.W|Timeout.|D3.L|Preserved.|
|A0.L|Channel ID.|A0.L|Preserved.|
|A1.L|Base of 1st Font.|A1.L|Corrupted.|
|A2.L|Base of 2nd Font.|A2.L|Preserved.|
===== Errors =====


|ERR_NC|Not complete.|
|ERR_NO|Channel not found.|


===== Notes =====
  * All registers not shown above are not used on entry and are preserved on exit.
  * The registers A1 and A2 each either point to a font or are zero in which case the relevant default font is set.
  * Each font must be stored in memory in a particular way as shown below.
  * The value in D2.L is ignored by QDOS, but if it is "DEFF" in SMSQ/E then any font set by this call is used in subsequently opened channels.
  * If a character sent to a window is a valid character in the first font it is printed otherwise if it is a valid character in the second font that will be printed. If no valid character is found in either font the first character in the second font will be printed.
===== Font Format =====


^Address^Length^Item^
|$00|Byte|1st valid character|
|$01|Byte|Number of valid characters|
|$02|9 bytes|1st character|
|$0B|9 bytes|2nd character|
|..|..|..|

Each character consists of a 5x9 array printed in a 6x10 rectangle and 
is stored in bits 6 to 2 in each byte of a set of 9 representing the printable rows from top to bottom. The top row in the 6x10 rectangle is blank.

QDOS Internals

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