: (ps2kcB) ( for port B )
	( Port B TL is bit 2 )
    0xdd PC@ 0x04 AND IF 0 EXIT ( nothing ) THEN
    0x3f PC@ DROP 0b01110111 ( Port B TH output, low ) 0x3f PC!
    0xdc PC@ ( bit 7:6 go in 1:0 ) 6 RSHIFT ( n )
    0xdd PC@ ( bit 1:0 go in 3:2 ) 0x03 AND 2 LSHIFT OR ( n )
    0b11110111 ( Port B TH output, high ) 0x3f PC!
    0xdc PC@ ( bit 7:6 go in 5:4 ) 0xc0 AND 2 RSHIFT OR ( n )
    0xdd PC@ ( bit 1:0 go in 7:6 ) 0x03 AND 6 LSHIFT OR ( n )
	( Port A/B reset ) 0xff 0x3f PC!
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