C51: Reserving Space in Code Banks

Information in this knowledgebase article applies to:

• C51 All versions

QUESTION

How can I reserve space in a couple of the banks in a code banking program?

ANSWER

Reserving code space in code banking applications requires that you use an assembler source module. For example:

RESERVE_BANK0 SEGMENT CODE
RSEG RESERVE_BANK0
DS      2000H           ; reserve 2000H bytes

RESERVE_BANK1 SEGMENT CODE
RSEG RESERVE_BANK1
DS      1000H           ; reserve 1000H bytes

END

Put the above code into an A51 source file (reserves.a51) and include it in your µVision project. Under the Linker options Additional tab, enter the following:

BANK0 (RESERVE_BANK0 (4000H))  /* set start address to 4000H */
BANK1 (RESERVE_BANK1 (5000H))  /* set start address to 5000H */

This reserves the memory regions 4000H-5FFFH in BANK0 and 5000H-5FFFH in BANK1.

If you are not using µVision, change your linker command line as follows:

BL51  , COMMON {RESERVES.OBJ} TO YOURPROG
     BANK0 (RESERVE_BANK0 (4000H))
     BANK1 (RESERVE_BANK1 (5000H))

MORE INFORMATION

• C51: Reserving Code Space
• C51: Accessing Specific Memory Bytes
• C51: Reserving Space in Code Memory

Last Reviewed: Thursday, February 25, 2021