Difference between revisions of "OSBYTE &79"
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Y=0 X=lowest internal keynumber to start at (for a range of keys) | Y=0 X=lowest internal keynumber to start at (for a range of keys) | ||
On exit X=earliest keynumber being pressed or &FF for none | On exit X=earliest keynumber being pressed or &FF for none | ||
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| + | ==Usage note== | ||
| + | On exit Y is undefined, and typically contains an invalid keynumber.<ref name="seddon-osbyte7a">Stardot forum [https://stardot.org.uk/forums/viewtopic.php?p=441827#p441827 post by Tom Seddon], 11th December 2024.</ref> Paged ROMs that handle [[Service calls|service call]] &03 commonly, though incorrectly, pass Y unchanged to [[OSBYTE &78]] where it sets an arbitrary keynumber as the second active rollover key. This does not cause a spurious keypress in practice. | ||
==See Also== | ==See Also== | ||
* http://mdfs.net/Docs/Comp/BBC/Osbyte00 | * http://mdfs.net/Docs/Comp/BBC/Osbyte00 | ||
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| + | == References == | ||
| + | <references/> | ||
[[User:Jgharston|Jgharston]] 21:56, 26 May 2009 (UTC) | [[User:Jgharston|Jgharston]] 21:56, 26 May 2009 (UTC) | ||
Latest revision as of 23:23, 17 December 2024
OSBYTE &79 (121) - Keyboard Scan
Y=0 X=internal keynumber EOR&80 for single key check On exit X<0 if the key was being pressed Y=0 X=lowest internal keynumber to start at (for a range of keys) On exit X=earliest keynumber being pressed or &FF for none
Usage note
On exit Y is undefined, and typically contains an invalid keynumber.[1] Paged ROMs that handle service call &03 commonly, though incorrectly, pass Y unchanged to OSBYTE &78 where it sets an arbitrary keynumber as the second active rollover key. This does not cause a spurious keypress in practice.
See Also
References
- ↑ Stardot forum post by Tom Seddon, 11th December 2024.
Jgharston 21:56, 26 May 2009 (UTC)
