OSWORD &33

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&33 51  Read/Write PRISMA overlay or nonvolatile memory		Prisma
	On entry:
		XY?0	 = command 0=Read overlay
				   1=Write overlay
				   2=Read nonvolatile memory
				   3=Write nonvolatile memory
		XY?1	 = Overlay/NVM page for definition
		XY?2	 = Overlay/NVM address
		XY?3	 = Number of bytes to transfer (1-12)
		XY?4..15 = Data

	The nonvolatile memory is organised as 32 pages of 256 bytes. The page
	allocation is as follows:
		 0-15 Default overlay definitions 0-15
		  16  Default standard resolution palette - Red
		  17  Default standard resolution palette - Green
		  18  Default standard resolution palette - Blue
		  19  Default standard resolution palette, normal BBC parameter
		  20  Default high resolution palette - Red
		  21  Default high resolution palette - Green
		  22  Default high resolution palette - Blue
		  23  Default high resolution palette, normal BBC parameter
		24-25 Reserved
		25-27 User applications
		28-31 System use

PRISMA calls

See Also

Jgharston (talk) 19:58, 25 October 2015 (UTC)