ZXSTSPECTRA

Paul Farrow's SPECTRA video interface for the 16k and 48k ZX Spectrum.
This provides new colour modes, a Kempston joystick interface, an Interface1 compatible RS232 port and an Interface2 compatible rom port with optional Interface1 compatible rom switching hooks.
If the joystick is enabled, then a block ZXSTKEYBOARD or ZXSTJOYSTICK for KEMPSTON emulation is used to store the SPECTRA's joystick port state.
A block ZXSTIF2ROM is used to store the rom contents of a rom module plugged into the SPECTRA's rom slot.


// Flags
#define ZXSTSPECTRA_new_colour_modes_enabled	1
#define ZXSTSPECTRA_rs232_enabled		2
#define ZXSTSPECTRA_joystick_enabled		4
#define ZXSTSPECTRA_if1_rom_hooks_enabled	8
#define ZXSTSPECTRA_rom_paged_in		16
#define ZXSTSPECTRA_port_239_comms_out_bit	32
#define ZXSTSPECTRA_port_239_cts_out_bit	64
#define ZXSTSPECTRA_port_247_data_out_bit	128
#define ZXSTSPECTRA_ram_page_0_embedded		0x100
#define ZXSTSPECTRA_ram_page_1_embedded		0x200
#define ZXSTSPECTRA_compressed			0x400


// SPECTRA video interface
typedef struct ZXSTSPECTRA
{
    ZXSTBLOCK	blk;
    WORD	flags;
    BYTE	port_7fdf;
    BYTE	port_fe;
    WORD	compressed_size_ram0;
    WORD	compressed_size_ram1;
    BYTE	data[1];
};


Members

blk
The block header. The block id is ZXSTBID_SPECTRA ('S', 'P', 'R', 'A').

flags
Various flags. This can be a combination of:

new_colour_modes_enabled
	Setting of the corresponding DIP switch on the interface
rs232_enabled
	Setting of the corresponding DIP switch on the interface
joystick_enabled
	Setting of the corresponding DIP switch on the interface
if1_rom_hooks_enabled
	Setting of the corresponding DIP switch on the interface
rom_paged_in
	the rom module, if present, was paged in at the moment the snapshot was made.
port_239_comms_out_bit
	state of the COMMS_OUT bit in port 239.
port_239_cts_out_bit
	state of the CTS output bit in port 239.
port_247_data_out_bit
	state of the data bit as written to port 247.
ram_page_0_embedded
	whether a dump of the first ram page is included in DATA[].
	if not embedded, use data from contended ram.
ram_page_1_embedded
	whether a dump of the second ram page is included in DATA[].
	if not embedded, use data from contended ram.
compressed
	data of ram page 0 and 1 is zlib compressed.
	they are compressed in 2 chunks, one per page, not in one chunk.


port_7fdf
last out to port 0x7FDF (colour mode register)

port_fe
last out to port 0xFE in enhanced border mode

compressed_size_ram0
0 if not included

compressed_size_ram1
0 if not included

data[1]
data of ram[0] and/or ram[1] depending on bits set in 'flags'