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        Port 061  -  8255A-5 Port B

            1xxx xxxx  0=Keyboard enable, 1=Keyboard acknowledge
                       PS/2: Write: Reset Timer 0 Output Latch (IRQ0)
                             Read:  Parity check (1=parity check occured).
            x1xx xxxx  PS/2: Read:  1=Channel check has occured.
            xx1x xxxx  0=Enable parity error signals from expansion
                         ports
                       PS/2: Read:  Timer 2 Output. This bit indicates the
                                    condition of the timer/counter 2 output
                                    signal.
            xxx1 xxxx  0=RAM parity error enable
                       PS/2: Read:  This bit tiggles for each refresh request.
            xxxx 1xxx  Casette motor on/off (only old PCs)
                       PS/2: Enable Channel Check (0=enabled - set to 1,
                             during a power-on reset).
            xxxx x1xx  Undefined/Speed Switch
                         On some XT-clones, this bit is used to switch
                         between 4.77 MHz and 8MHz mode.
                         0=4.77 MHz, 1=8 MHz.
                       PS/2: Enable Parity Check (0=enabled - set to 1,
                             during a power-on reset).
            xxxx xx1x  1=Speaker enabled
            xxxx xxx1  Speaker input gate
                       1=8253 channel 2
                       0=Direct speaker control via bit 1