80-Bus News |
May–June 1984, Volume 3, Issue 3 |
|
|
|
Page 22 of 51 |
|
|
|
---|
As a brief aside on FILL routines – You can always tell a recursive based FILL routine, as, when it is filling a complex area, there are often pauses while nothing apparently happens on the screen. What is actually happening is that the FILL routine has just filled to a ‘dead end’, and there then follows a period where the recursive structure ‘unwinds’ itself, returning from layer to layer back up the stack until it finds an area that it has not yet filled.
Well folks, it had to happen. Between writing the first part of this article and completing this one someone has unearthed a bug that is present in both the IVC and SVC monitors. That fact that it has taken so long to surface is indicative that none of you are likely to have met it yet (otherwise you would have reported it – wouldn’t you?). It is in the ESC “f” ... sequence that allows you to redfine the function keys from a program. If you try and ‘undefine’ a key using this sequence the key is not actually fully deleted from the function key table, and if the key is subsequently pressed something will be returned to the host system. What the ‘something’ is cannot be easily predicted. Key definitions can be removed totally from the table, but only by using the Shift/Edit feature direct from the keyboard.
HEX | ASCII | DECIMAL | COMMAND |
General | |||
---|---|---|---|
07 | ^G | 7 | Bell – sound on-board buzzer |
Cursor Movement | |||
1B 0C | <ESC> ^L | 27 12 | Cursor home |
Screen format | |||
1B 34 | <ESC> “4” | 27 52 | Select graphics mode |
1B 70... | <ESC> “p”... | 27 112... | Select display/update partition |
Character set | |||
1B 67... | <ESC> “g”... | 27 103... | Set Language |
1B 62... | <ESC> “b”... | 27 98... | Read back character set |
256x256 graphics | |||
1B 52 | <ESC> “R”... | 27 82... | Reset point X,Y |
1B 53... | <ESC> “S”... | 27 83... | Set point X,Y |
1B 54... | <ESC> “T”... | 27 84... | Test point X,Y |
1B 6C... | <ESC> “l”... | 27 108... | Draw/Erase/Complement a line |
1B 6F... | <ESC> “o”... | 27 111... | Draw/Erase/Complement a circle |
1B 6D... | <ESC> “m”... | 27 109... | Move cursor to X,Y |
1B 77 | <ESC> “w”... | 27 119 | Fill a polygon |
1B 64... | <ESC> “d”... | 27 100... | Graphics screen dump |
Keyboard | |||
1B 3E... | <ESC> “>”... | 27 62... | Download soft-key display |
Clock | |||
1B 74... | <ESC> “t”... | 27 116... | Set clock time |
1B 74 3D.. | <ESC> “t=”... | 27 116 61. | Position clock display |
1B 74 45 | <ESC> “tE” | 27 116 69 | Enable clock display |
1B 74 44 | <ESC> “tD” | 27 116 68 | Disable clock display |
1B 74 3F | <ESC> “t?” | 27 116 63 | Return clock time |
Miscellaneous | |||
1B 61... | <ESC> “a”... | 27 97... | Set/reset attributes |
|
|
|
Page 22 of 51 |
|
|
|
---|