OS_Byte 200 (changes)
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Programmer's OS Reference SWI Manuals Calls
» Part OS_Byte 15 – SWI Calls
» OS_Byte 200OS
» OS_Byte
» OS_Byte 200
OS_Byte 200
(SWI &06)
| Entry | |
|---|---|
| R0 | 200 (&C8) |
| R1 | EOR value |
| R2 | AND value |
| Exit | |
|---|---|
| R0 | Preserved |
| R1 | State before being overwritten |
| R2 | Keyboard disable flag (see OS_Byte 201) |
Use
The purpose of this call is to read or write the Break and Escape effect.
Notes
This call can read, or change, the effects of a reset (including resets caused by Break) and of Escape.
The bottom two bits of R1 have the following significance:
|<^{width:4em}. Bit|_<^{width:4em}. Value|<^. Effect|
|/2<^. 0|<^. 0|<^. Normal escape action|
|<^. 1|<^. Escape disabled unless caused by OS_Byte 125|
|/2<^. 1|<^. 0|<^. Normal reset action|
|<^. 1|<^. Power on reset (only if bits 2-7 of R1 are zero) This means a value of %00000001x causes a memory clear (no matter what kind of reset was pressed)|
| Bit | Value | Effect |
|---|---|---|
| 0 | 0 | Normal escape action |
| 1 | Escape disabled unless caused by OS_Byte 125 | |
| 1 | 0 | Normal reset action |
| 1 | Power on reset (only if bits 2-7 of R1 are zero) This means a value of %00000001x causes a memory clear (no matter what kind of reset was pressed) |
See also
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