OS_Byte 218 (changes)
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Programmer's OS Reference SWI Manuals Calls
» Part OS_Byte 15 – SWI Calls
» OS_Byte 218OS
» OS_Byte
» OS_Byte 218
OS_Byte 218
(SWI &06)
| Entry | |
|---|---|
| R0 | 218 (&DA) |
| R1 | EOR value |
| R2 | AND value |
| Exit | |
|---|---|
| R0 | Preserved |
| R1 | Previous count |
| R2 | Corrupted |
Use
The purpose of this call is to read or write the count of bytes in the VDU queue.
Notes
The value of the count is -(bytes needed to complete VDU sequence) held in 1 byte, so if two bytes are needed to complete the current sequence then count will be &FE.
Usually this call is used to set the count to 0, which abandons any current VDU sequence. This stops error messages being garbled by a partially completed VDU sequence.
See also
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