Intel 87C196CB, 8XC196NT I/O Ports, 4. Extended Port Input EPPIN Register, Eppin, Function, Epreg

Models: 8XC196NT 87C196CB

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EP_PIN

 

 

I/O PORTS

 

 

 

EP_PIN

Address:

1FE7H

 

Reset State:

XXH

Each bit of the extended port input (EP_PIN) register reflects the current state of the corresponding pin, regardless of the pin configuration.

7

PIN7

PIN6

PIN5

PIN4

 

 

 

 

0

PIN3

PIN2

PIN1

PIN0

 

 

 

 

Bit

Bit

Function

Number

Mnemonic

 

 

 

 

7:0

PIN7:0

Extended Address Port Pin x Input

 

 

This bit contains the current state of EPORT.x.

 

 

 

Figure 5-4. Extended Port Input (EP_PIN) Register

EP_REG

Address:

1FE5H

 

Reset State:

00H

Each bit of the extended port data output (EP_REG) register contains data to be driven out by the corresponding pin. When a pin is configured as standard I/O (EP_MODE.x = 0), the result of a CPU write to EP_REG is immediately visible on the pin.

During nonextended data accesses, EP_REG contains the value of the memory page that is to be accessed. For compatibility with software tools, clear the EP_REG bit for any EPORT pin that is configured as an extended-address signal (EP_MODE.x set).

7

PIN7

PIN6

PIN5

PIN4

 

 

 

 

0

PIN3

PIN2

PIN1

PIN0

 

 

 

 

Bit

Bit

Function

Number

Mnemonic

 

 

 

 

7:0

PIN7:0

Extended Address Port Pin x Output

 

 

If EPORT.x is to be used as an output, write the data that it is to drive

 

 

out.

 

 

If EPORT.x is to be used as an input, set this bit.

 

 

If EPORT.x is to be used as an address line, write the correct value for

 

 

the memory page to be accessed by nonextended instructions.

 

 

 

Figure 5-5. Extended Port Data Output (EP_REG) Register

5-3

Page 52
Image 52
Intel 87C196CB I/O Ports, 4. Extended Port Input EPPIN Register, 5. Extended Port Data Output EPREG Register, Eppin, Epreg