MegaROM emulator for Turbo R

Pages 0x180..0x1ff are mapped to the internal RAM, so max 1MB.
The internal SRAM of the turboR can also be read/written via this mapper (pages 0x80..0x87).

wouter_, this is what PanasonicRam implements, I guess, right?

This is a copy & paste from an old article I wrote for SD MESXES fanzine:

		Memory area		Memory register
	
		#0000-#1FFF		#6000-#63FF
		#2000-#3FFF		#6400-#67FF
		#4000-#5FFF		#6800-#6BFF
		#6000-#7FFF		#6C00-#6FFF
		#8000-#9FFF		#7000-#73FF
		#A000-#BFFF		#7800-#7BFF
		#C000-#DFFF		#7400-#77FF
		#E000-#FFFF		#7C00-#7FEF


	Bank selected in that area:(#7FF9 bit 2 must be set)
    #7FF0	(R)	#0000-#1FFF
    #7FF1	(R)	#2000-#3FFF
    #7FF2	(R)	#4000-#5FFF
    #7FF3	(R)	#6000-#7FFF
    #7FF4	(R)	#8000-#9FFF
    #7FF5	(R)	#A000-#BFFF
    #7FF6	(R)	#C000-#DFFF
    #7FF7	(R)	#E000-#FFFF
			

    #7FF8	(R/W)	9th bit of the bank
		bit0	#0000-#1FFF
		bit1	#2000-#3FFF
		bit2	#4000-#5FFF
		bit3	#6000-#7FFF
		bit4	#8000-#9FFF
		bit5	#A000-#BFFF
		bit6	#C000-#DFFF
		bit7	#E000-#FFFF

    #7FF9	(R/W)	Config register

		bit 2	1: Enables reading #7FF0-7FF7
		bit 3	1: Enables reading #7FF9
		bit 4	1: Enables register at #7FF8

Bank content:

	#000 Turbo R firmware
	#028 Main ROM
	#080 SRAM
	#100 ROM Disk (GT only)
	#180 Main RAM

Memory registers work like MegaROM mapper registers. So writing to that areas select a bank/page.
I.e.: If you write #80 in #6C00 you will select SRAM in #6000-#7FFF

Notice that #7FF0-#7FF9 are read only!

Yes, they can be written when RAM or SRAM is selected.
What I wanted to mean is that #7FF0-#7FF9 are read only to check the selected bank. You can't change the bank writing to them.