helper_notes

"Z80 Instruction Information" flags:
C   Z  P/V  S   N   H

Decoding-bits:
	xxppqzzz

Registers (Spiffy offsets):
	PCAFBCDEHLIxIyiRSPafbcdehl
	1032547698badcfe1032547698
	PC = Program Counter
	A = Accumulator
	F = Flags register [7]SZ5H3PNC[0]
	BC, DE, HL: user registers
	Ix, Iy: Index registers
	i: Interrupt Vector
	R: Memory Refresh
	SP: Stack Pointer
	afbcdehl: Alternate register set (EX/EXX)

	tbl_r: B C D E H L (HL) A
	tbl_rp: BC DE HL SP
	tbl_rp2: BC DE HL AF
	
Shiftstate bits: 1=CB 2=ED 4=DD 8=FD

'cc' conditions:
	[0]NZ	Z	NC	C	PO	PE	P	M[7]

block instructions:
	y: 4=I 5=D 6=IR 7=DR	== b0: DEC (else INC); b1: REPEAT
	z: 0=LD 1=CP 2=IN 3=OUT
		LDxx: LD (DE),(HL); DE+-; HL+-; BC--; R? BC? PC-=2.
		CPxx: CP A,(HL); HL+-; BC--; R? BC&&(A!=old(HL))? PC-=2.
		INxx: IN (HL), port(BC); HL+-; B--; R? B? PC-=2.
		OTxx: B--; OUT port(BC),(HL); HL+-; R? B? PC-=2.

IM:
	The undoc IM 0/1 (ED 4E and others) sets IM 0 (The Undocumented Z80 Documented)

Register starting values: http://www.worldofspectrum.org/forums/showthread.php?t=34574

Timing reference for 128k: http://www.worldofspectrum.org/faq/reference/128kreference.htm (may be somewhat bogus)