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Save SPECTRA state in .z80 file						Kio 2016-03-05
===============================

This file describes the enhancements made by zxsp to save the SPECTRA state in a .z80 file.


SUMMARY
=======

Snapshots containing state of a SPECTRA interface must be saved in version 3 of the .z80 file format.
Bit 3 in byte "rldiremu" indicates presence of the SPECTRA interface.
Bits 5-7 in byte "data" store bits 5-7 of the border color. NOTE: in version 1.45 bit 5 indicated compressed data.
2 Bytes are appended to the normal .z80 header to store the SPECTRA state.
Memory pages 12, 13 and 14 are assigned to the rom slot and the SPECTRA ram.



HEADER
======

	// Z80 Version 1.45 Header

	uint8 a,f,c,b,l,h,pcl,pch,spl,sph,i,r;
	uint8 data			Bit 0  : Bit 7 of the R-register
						Bit 1-3: Bits 0-2 of the border colour
						Bit 4  : 1 = Basic SamRom switched in
						Bit 5-7: Bits 5-7 of the border colour		***SPECTRA***
	uint8 e,d,c2,b2,e2,d2,l2,h2,a2,f2;
	uint8 yl,yh,xl,xh,iff1,iff2;
	uint8 im;

	// Z80 version 2.01 enhanced header if pch=pcl=0:

	uint16 h2len;
	uint16 npc;
	uint8 model;
	uint8 port_7ffd_or_port_f4;
	uint8 if1paged_or_port_ff;
	uint8 rldiremu			Bit 0: 1 = R register emulation on
							Bit 1: 1 = LDIR emulation on
							Bit 2: 1 = AY sound in use, even on 48K machines
							Bit 3: 1 = SPECTRA interface present		***SPECTRA***
							Bit 6: 1 = (if bit 2 set) Fuller Audio Box emulation
							Bit 7: 1 = Modify hardware 
	uint8 port_fffd
	uint8 soundreg[16]

	// Z80 version 3.0 enhanced header if pcl=pch=0 & h2len≥54:

	uint8 t_l,t_m,t_h
	uint8 spectator
	uint8 mgt_paged
	uint8 multiface_paged
	uint8 ram0,ram1
	uint8 joy[10]
	uint8 stick[10]
   	uint8 mgt_type
	uint8 disciple_inhibit_button_status
	uint8 disciple_inhibit_flag


	// warajewo/xzx extension if pcl=pch=0 & h2len≥55:

	uint8 port_1ffd
	
	// zxsp extension for SPECTRA interface. pcl=pch=0 & h2len≥57:
	
	uint8 spectra_bits		Bit 0: new colour modes enabled			***SPECTRA***
							Bit 1: RS232 enabled           
							Bit 2: Joystick enabled        
							Bit 3: IF1 rom hooks enabled   
							Bit 4: rom paged in            
							Bit 5: port 239: Comms out bit 
							Bit 6: port 239: CTS out bit   
							Bit 7: port 247: Data out bit  
	uint8 spectra_port_7fdf	last out to port 7FDF		   			***SPECTRA***



MEMORY PAGES
============

The page numbers are as follows:

	pg no.	memory bank
	------	-----------
	12		SPECTRA rom
	13		SPECTRA ram[0]
	14		SPECTRA ram[1]
	

When writing a .z80 file, 

	If a rom cartridge is inserted into the SPECTRA rom slot, 
	then the rom should be saved in the .z80 file.

	If the SPECTRA shadow screen bit (port 7fdf bit 6) was ever set, 
	then the SPECTRA ram should be saved in the .z80 file. 


When reading a .z80 file, 

	page 12: load into SPECTRA rom
	page 13: load into SPECTRA ram[0]
	page 14: load into SPECTRA ram[1]

	zxsp 16/48k:
	page 8: also load into SPECTRA ram[0] if page 13 was not yet loaded

	zxsp +128k / +3 / +2A:
	page 5: also load into SPECTRA ram[0] if page 13 was not yet loaded
	page 7:	also load into SPECTRA ram[1] if page 14 was not yet loaded