OSWORD &33

&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

• OSWORD &28 Read PRISMA information table
• OSWORD &29 Read PRISMA pixel value
• OSWORD &2A Read PRISMA logical screen size
• OSWORD &2B Read PRISMA colour palette
• OSWORD &2C Send VDU sequence direct to PRISMA
• OSWORD &2D Read last two PRISMA graphics cursors
• OSWORD &2E Read PRISMA base screen visible origin
• OSWORD &2F Read PRISMA graphics origin
• OSWORD &30 Read PRISMA interrupt status
• OSWORD &31 Direct call to PRISMA command
• OSWORD &32 Read position of PRISMA-3 roller screen
• OSWORD &33 Read/Write PRISMA overlay or nonvolatile memory

See Also

• http://mdfs.net/Docs/Comp/BBC/Oswords

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