Thanks for the answers. Now I realized that I was trying to solve the wrong problem :'(.
I worked on some custom protocol to send data between Arduino and MSP430F2013. It only worked on and off. I spent most of the time tuning the timing, however without realizing that my 2D array exceeds the 1K RAM size limit of Arduino, which is the real problem.
Unfortunately its IDE doesn't warm me that my byte array used up of the RAM (like IAR IDE does).
Fortunately once the problem is identified, I can quickly googled out a solution by storing my byte array in the flash memory.
prog_uchar data[20][64] PROGMEM = ...
... ...
... = (byte)pgm_read_byte(&data*[j]);*
... ...
(http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=38003&postdays=0&postorder=asc)
(PROGMEM - Arduino Reference)
(avr-libc: <avr/pgmspace.h>: Program Space Utilities)
After thought, the Arduino IDE's easiness to use totally makes me unconscious of my dealing with a MCU (where RAM size is a very limited resource). I worked very hard to fit my code into MSP430F2013's 128B RAM. And IAR IDE will warn me if things don't fit. It would be great if Arduino can have that function as well as step-by-step debugging. Am I being too greedy 