REG OFFSET
NAME
(hex)
2A
DESCRIPTION
General Purpose I/0 bit 1.7
GP17
Bit[0] In/Out : =1 Input, =0 Output
Bit[1] Polarity : =1 Invert, =0 No Invert
Bit[2] Alternate Function Select
1= J2Y (Joystick 2, Y-Axis RC Constant)
0=GPIO
Default = 0x01
on VTR POR
(R/W)
Bits[6:3] Reserved
Bit[7] Output Type Select
1=Open Drain
0=Push Pull
GP20
2B
General Purpose I/0 bit 2.0
Bit[0] In/Out : =1 Input, =0 Output
Bit[1] Polarity : =1 Invert, =0 No Invert
Bit[2] Alternate Function Select
1=8042 P17 function (User Note 2)
0=Basic GPIO function
Default = 0x01
on VTR POR
(R/W)
Bits[6:3] Reserved
Bit[7] Output Type Select
1=Open Drain
0=Push Pull
GP21
2C
General Purpose I/0 bit 2.1
Bit[0] In/Out : =1 Input, =0 Output
Bit[1] Polarity : =1 Invert, =0 No Invert
Bit[3:2] Alternate Function Select
11= nDS1 – Floppy Drive Select 1 (Note 4)
10=Either Edge Triggered Interrupt Input 0 (Note 1)
01=8042 P16 function (User Note 2)
00=Basic GPIO function
Default =0x01
on VTR POR
(R/W)
Bits[6:4] Reserved
Bit[7] Output Type Select
1=Open Drain
0=Push Pull
GP22
2D
General Purpose I/0 bit 2.2
Bit[0] In/Out : =1 Input, =0 Output
Bit[1] Polarity : =1 Invert, =0 No Invert
Bit[3:2] Alternate Function Select
11= nMTR1 – Floppy Motor Select 1 (Note 4)
10=Either Edge Triggered Interrupt Input 1 (Note 1)
01=8042 P12 function (User Note 2)
00=Basic GPIO function
Default =0x01
on VTR POR
(R/W)
Bits[6:4] Reserved
Bit[7] Output Type Select
1=Open Drain
0=Push Pull
N/A
2E
(R)
2F
Reserved – reads return 0
GP24
General Purpose I/0 bit 2.4
Bit[0] In/Out : =1 Input, =0 Output
Bit[1] Polarity : =1 Invert, =0 No Invert
Bit[2] Reserved
Default = 0x01
on VTR POR
(R/W)
Bits[6:3] Reserved
Bit[7] Output Type Select
1=Open Drain
0=Push Pull
Page 131
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