C51: CODE BANKING WITH ON-CHIP AND OFF-CHIP MEMORY

Information in this article applies to:

• C51 All Versions

QUESTION

Is it possible to use code banking with 32KB on-chip Flash ROM in combination with 128KB off-chip (external) Flash ROM? I'm planning to use a Philips P89C662 but my program will go beyond the 64KB limit. What, if any, are the special considerations I need to know about for this configuration?

ANSWER

Yes. You can use on-chip and off-chip Flash ROM in combination for code banking applications.

When you use the 32KB on-chip Flash ROM as the Common Area and the off-chip Flash ROM as 4 banks of 32KB, you may simply connect A15 and A16 of the off-chip Flash ROM to some port pins of the 8051 device. A separate latch for the bank switch address lines is not required since bank switching takes place in the on-chip Flash.

MORE INFORMATION

• Refer to Code Banking in the BL51 User's Guide.
• Refer to Examples in the BL51 User's Guide.

SEE ALSO

• C51: CREATING CODE BANKING PROGRAMS
• BL51: THE CODE BANKING MECHANISM

Last Reviewed: Monday, July 18, 2005