Torch I/O Map: &00-&03 - Page ROM in, access 8255 register &04-&07 - Page ROM out, access 8255 register &00/&04 - Port A Data I/O, Tube Data out &01/&05 - Port B Data I/O, Tube Data in &02/&06 - Port C Data I/O, Tube Status b7----b1- - OUTRDY---INRDY- &03/&07 - 8255 control &08-&0F - unused &10+reg - Z80 SIO &00+reg - 8255 PIA &08+reg - unused &10+reg - Z80 SIO &18+reg - Baud rate : A4 - 0=Tube registers, 1=TOSCA A3 - A2 - 0=page ROM in, 1=page ROM out A1 - A0 - A43210 xx0xx Page ROM in xx1xx Page ROM out 0xxrr 8255 register 10xrr Z80 SIO 11xxr Write to 3x74LS151 - select baud rates 11xx0 b6b5b4=extclk2 b2b1b0=extclk1 11xx1 b2b1b0=SIO clock 000=highest, 111=lowest 19200 0 9600 1 4800 2 2400 3 1200 4 600 5 300 6 150 7 From 6502 side: &FEE0-&FEFF - TUBE A4=0 - access 6522 connected to 8255 A4=1 - reset Z80 board 6522 Port A <--> Port A 8255 6522 Port B <--> Port B 8255 6522 CA1 <--> Port C bit 7 6522 CA2 <--> Port C bit 6 6522 CB1 <--> Port C bit 1 6522 CB2 <--> Port C bit 2