OSWORD &29

&29 41  Read PRISMA pixel value					Prisma
	On entry:
		XY?0..1 = X coordinate
		XY?2..3 = Y corrdinate
	On exit:
		XY?4    = logical colour of pixel at X,Y
		XY?5..7 = reserved
		XY?8    = &FF=pixel outside graphics windows
	If the *POINT command has been used, then OSWORD 9 (POINT) passes
	and returns the same information in XY+0 to XY+4.

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) 19:51, 25 October 2015 (UTC)