Difference between revisions of "OSBYTE &B9"

Latest revision as of 19:12, 8 March 2015

OSBYTE &B9 (185) - Read MOS copy of palette register

   (Electron OS)
   Read/Write ROM polling semaphore
   This is the value adjusted by *FX22 and *FX23

@@ Line 1: / Line 1: @@
 [[Category:OSBYTE]]
-OSBYTE &B9 (185) - Read/Write MOS copy of palette register/ROM polling semaphore
+OSBYTE &B9 (185) - Read MOS copy of palette register
-     On the BBC, B+ and Master, this contains the MOS's copy of the palette
+     (Electron OS)
-    register in the video ULA.
+     Read/Write ROM polling semaphore
+     This is the value adjusted by *FX22 and *FX23
-    On the Electron there is no video ULA, and this location contains the ROM
-    polling semaphore. When the semaphore is non-zero the 100Hz ROM service
-     call &15 is sent to ROMs. The semaphore is normally accessed with *FX23
-    to increment it and *FX24 to decrement it.
 ==See Also==
-* [[OSBYTE &16|OSBYTE &16]] - Increment ROM polling semaphore
+* http://mdfs.net/Docs/Comp/BBC/OsbyteA6
-* [[OSBYTE &17|OSBYTE &17]] - Decrement ROM polling semaphore
-* [[OSBYTE &B3|OSBYTE &B3]] - Master ROM polling semaphore location
-* [[Paged ROM service calls]]
-[[User:Jgharston|Jgharston]] 22:30, 26 May 2009 (UTC)
+[[User:Jgharston|Jgharston]] 22:34, 26 May 2009 (UTC)