tmp88cs34ng TOSHIBA Semiconductor CORPORATION, tmp88cs34ng Datasheet - Page 39

• Manufacturer Part Number: tmp88cs34ng
• Description: Cmos 8-bit Microcontroller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

1.7.3
(1) Program jump mode
execution reaches the instruction at the corrective ROM address, skips from the instruction
which would have been executed, and executes an instruction at a preset jump address.
ROMCDR to set the corrective ROM address and jump address.
the patch program is a jump address, the bug in the erroneous program can be fixed. Note
that the patch program should end with a jump instruction, which causes a return to the
built-in ROM.
Functions
corresponding four banks of ROM corrective registers. Either program jump mode or data
replacement mode is selected for each bank by CM0 to CM3 respectively.
Note: For program jump mode, the address to be corrected must be the start address of the
In the program jump mode, the system executes a jump instruction when the program
Clearing ROMCCR CMx (x: 0 to 3) to “0” puts the system in the program jump mode. Use
When the start address of an erroneous program is a corrective ROM address, and that of
Example 1: Setting the Program Correction Circuit with the Initial Routine
Example 2: There is bugs on the locations from 0C020H to 0C085H
The ROM corrective function can correct maximum four ROM areas with their
program correction circuit's register and stores the patch program into the built-in
RAM as follows.
information to patch the ROM with the bugs must be read out from any of memory
storage that holds them during initial program routine. CMn = 0 specifies the program
jump mode. Subsequently, the patch program codes are loaded into RAM (00400H to
004EFH). The start address (0C020H) of the ROM necessary to patch is written to the
corrective ROM address registers, and the start address (00400H) of the RAM area to
patch is loaded onto the jump address registers. When the instruction at 0C020H is
fetched, the instruction to jump into 00400H is unconditionally executed instead of the
instruction at 0C020H, and the subsequent patch program codes are executed. The
jump instruction at the end of the patch program codes returns to the ROM at 0C086H.
1.
2.
3.
4.
5.
6.
7.
8.
Using the initial routine program, which is executed right after reset, set the
The corrective address, the jump vector, the program patch codes and other
instruction.
Read the flag, which indicates whether to use the program correction circuit, from
the external memory.
If that circuit is not used, perform normal initial processing.
If it is used, clear CMx to 0 to establish the program jump mode.
Read the corrective ROM address and jump address from the external memory.
Set the corrective ROM address and jump address, which were read in step 4., in
ROMCDR.
Read the number of bytes for the patch program from the external memory.
Read the program with a number of bytes, equal to the byte count read in step 6.,
from the external memory, and store that program into the built-in RAM.
Repeat steps 4. through 7. as many times as there are required banks.
88CS34-39
TMP88CS34/CP34
2007-09-12