Intel 80C196NU, 8XC196NP, Microcontroller manual Epreg, X0H

Models: Microcontroller 80C196NU 8XC196NP

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REGISTERS

 

 

EP_REG

 

 

 

EP_REG

Address:

1FE5H

 

Reset State:

X0H

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).

80C196NU Only: For nonextended data accesses, the 80C196NU forces the page address to 00H. You cannot change pages by modifying EP_REG.

7

 

 

 

 

0

PIN3

PIN2

PIN1

PIN0

 

 

 

 

Bit

Bit

Function

Number

Mnemonic

 

 

 

 

7:4

Reserved; always write as zeros.

 

 

 

3:0

PIN3:0

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.

 

 

For the 8XC196NP, 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.

 

 

The 80C196NU forces the page address to 00H. You cannot change

 

 

pages by modifying EP_REG

 

 

 

C-17

Page 408
Image 408
Intel 80C196NU, 8XC196NP, Microcontroller manual Epreg, X0H