OSWORD &31

&31 49  Direct call to PRISMA command				Prisma
	On entry:
		XY?0   = command
		XY?1   = number of parameters
		XY?2.. = command parameters

	Commands are:
	XY?0		XY?1	XY?2..
	  0 *BLANK	 0
	  1
	  2 *CENTRE	 2
	  3 *COLOUR	 1
	  4 *DOWN	 1
	  5 *FIELD	 0
	  6 *GENLOCK	 0 or 1
	  7
	  8 *GOPT	 1 or 2
	  9 *GRAPHICS	 0 or 1
	 10
	 11 *GTV	 1 or 2
	 12 *INIT	 0
	 13 *LEFT	 1
	 14 *OVERLAY	 1 or 2
	 15 *PALETTE	 1 or 2
	 16 *POINT	 0 or 1
	 17 *PROFF	 0
	 18 *RIGHT	 1
	 19 *ROLLER	 0 or 1
	 20 *ROTATE	 1
	 21 *SPLIT	 1
	 22 *TEXT	 0 or 1
	 23 *TZOOM	 1 or 2
	 24 *UNBLANK	 0
	 25 *UP		 1
	 26 *VKEY	 1
	 27 *WIDTH	 1
	 28 *WINDOW	 1
	 29 *ZOOM	 1 to 4
	 30
	 31 *FGRAB	 1 or 2
	 32 *HOLD	 1
	 33 *LEVEL	 1 or 2
	 34 *LPHASE	 1
	 35 *BUFFER	 1
	128 Extend or re-allocate working buffer
		XY?1=buffer address high byte in I/O memory
		XY?2=number of pages
	129 Define pixel translation table
		XY?1..2=translation table address in I/O memory

	This call provides a fast interface to all of the PRISMA-3
	*commands, except the *CONFIGURE, *GSAVE and *GLOAD commands
	which require string parameters. Errors are generated in the
	same way as the *commands.

	The count at XY?1 is the number of parameters passed to the
	call, not the number of bytes passed. A 16-bit parameter is
	passed in two bytes but is counted as one parameter. For
	instance, *ZOOM 5 is passed as 29,1,5,0.

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) 19:56, 25 October 2015 (UTC)