，GBA link-port pinout
--------------------
_______
/ 5 3 1 \
| 6 4 2 |    (looking at GBA link-port)
'-------'

1    VCC
2    SO
3    SI
4    SD
5    SC
6    GND



schematics
----------

GBA            MAX3222CPN     PC (9 pins female)
---            ----------     ------------------
SO 2 ---------> 12 -> 15 -----> 2 RxD
SI 3 <--[R]---- 13 <- 14 <----- 3 TxD
SD 4 ---------> 11 -> 8  -----> 8 CTS
SC 5 <--[R]---- 10 <- 9  <----- 7 RTS

VCC 1 -.------- 17
       +------- 18
       |
       `-+|(-.
             |
GND 6 -.-----+- 16
       +---------------------- 5 GND
       +------- 1
       +--)|+-- 3
       `-+|(--- 7

       .--)|+-- 2
       `------- 4

       .--)|+-- 5
       `------- 6



Resistors
    I used 390 ohms, but Jeff advises 1 KOhms on this. see url above for
his FAQ.
    This is used to prevent short circuit.
    Actually there's no need for a resistor in the SI line as this must
be input anyway:
    according docs: "Always set the SI terminal to an input.  If it is
set to an output, a problem may occur with some connecting equipment."

Capacitors
    5 pieces, each 0.1uF
    Drawn in ascii as: ----)|+---   (where + is the positive end)

MAX3222CPN
    get one (or two;) samples of the MAX3222CPN at www.maxim-ic.com
    note that 'CPN' is the DIL version.