UPD75P3036 NEC, UPD75P3036 Datasheet - Page 15

• Manufacturer Part Number: UPD75P3036
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER
• Manufacturer: NEC

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4. Mk I MODE AND Mk II MODE SELECTION FUNCTION
Setting a stack bank selection (SBS) register for the PD75P3036 enables the program memory to be switched between
Mk I mode and Mk II mode. This function is applicable when using the PD75P3036 to evaluate the PD753036.
When the SBS bit 3 is set to 1 : sets Mk I mode (supports Mk I mode for PD753036)
When the SBS bit 3 is set to 0 : sets Mk II mode (supports Mk II mode for PD753036)
4.1 Difference between Mk I Mode and Mk II Mode
Table 4-1 lists points of difference between the Mk I mode and the Mk II mode for the PD75P3036.
Caution The Mk II mode supports a program area exceeding 16 Kbytes for the 75X and 75XL series.
Program counter
Program memory (bytes)
Data memory (bits)
Stack
Instruction
Instruction
execution time CALLF !faddr instruction
Supported mask ROM versions
Therefore, this mode is effective for enhancing software compatibility with products exceeding 16
Kbytes.
When the Mk II mode is selected, the number of stack bytes used during execution of subroutine
call instructions increases by one byte per stack compared to the Mk I mode. When the CALL !addr
and CALLF !faddr instructions are used, the machine cycle becomes longer by one machine cycle.
Therefore, use the Mk I mode if the RAM efficiency and processing performance are more important
than software compatibility.
Stack bank
No. of stack bytes
BRA !addr1 instruction
CALLA !addr1 instruction
CALL !addr instruction
Item
Table 4-1. Difference between Mk I Mode and Mk II Mode
PC
16384
768 x 4
Selectable via memory banks 0 to 2
2 bytes
Not available
3 machine cycles
2 machine cycles
When set to Mk I mode for PD753036
13-0
Mk I Mode
4 machine cycles
3 machine cycles
3 bytes
Available
When set to Mk II mode for PD753036
Mk II Mode
PD75P3036
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