Summary of CIO Registers (Index 00h..2Fh)
00h - Master Interrupt Control Register (R/W)
01h - Master Configuration Control Register (R/W)
02h - Interrupt Vector Register Port A (R/W)
03h - Interrupt Vector Register Port B (R/W)
04h - Interrupt Vector Register Counter/Timers (R/W)
05h - Data Path Polarity Register Port C (4 LSBs only) (R/W)
06h - Data Direction Register Port C (4 LSBs only) (R/W)
07h - Special I/O Control Register Port C (4 LSBs only)(R/W)
08h - Port A Command and Status Register (Parts R/W)
09h - Port B Command and Status Register (Parts R/W)
0Ah - Counter/Timer 1 Command and Status (Parts R/W)
0Bh - Counter/Timer 2 Command and Status (Parts R/W)
0Ch - Counter/Timer 3 Command and Status (Parts R/W)
0Dh - Port Data Register Port A (R/W) (directly addressable)
0Eh - Port Data Register Port B (R/W) (directly addressable)
0Fh - Port Data Register Port C (R/W) (directly addressable)
10h - Counter/Timer 1 Current Count Register MSB (R)
11h - Counter/Timer 1 Current Count Register LSB (R)
12h - Counter/Timer 2 Current Count Register MSB (R)
13h - Counter/Timer 2 Current Count Register LSB (R)
14h - Counter/Timer 3 Current Count Register MSB (R)
15h - Counter/Timer 3 Current Count Register LSB (R)
16h - Counter/Timer 1 Time Constant Register MSB (R/W)
17h - Counter/Timer 1 Time Constant Register LSB (R/W)
18h - Counter/Timer 2 Time Constant Register MSB (R/W)
19h - Counter/Timer 2 Time Constant Register LSB (R/W)
1Ah - Counter/Timer 3 Time Constant Register MSB (R/W)
1Bh - Counter/Timer 3 Time Constant Register LSB (R/W)
1Ch - Counter/Timer 1 Mode Specification (R/W)
1Dh - Counter/Timer 2 Mode Specification (R/W)
1Eh - Counter/Timer 3 Mode Specification (R/W)
1Fh - Current Vector Register (R)
20h - Port A Mode Specification Register (R/W)
21h - Port A Handshake Specification Register (R/W)
22h - Data Path Polarity Register Port A (R/W)
23h - Data Direction Register Port A (R/W)
24h - Special I/O Control Register Port A (R/W)
25h - Port A Pattern Polarity (PP) Register (R/W)
26h - Port A Pattern Transition (PT) Register (R/W)
27h - Port A Pattern Mask (PM) Register (R/W)
28h - Port B Mode Specification Register (R/W)
29h - Port B Handshake Specification Register (R/W)
2Ah - Data Path Polarity Register Port B (R/W)
2Bh - Data Direction Register Port B (R/W)
2Ch - Special I/O Control Register Port B (R/W)
2Dh - Port B Pattern Polarity (PP) Register (R/W)
2Eh - Port B Pattern Transition (PT) Register (R/W)
2Fh - Port B Pattern Mask (PM) Register (R/W)
30h..3Fh - Reserved