What is a Biversion you ask? Well, all LCD displays have two polarisers on them. If you rotate one, the image becomes inverted; AKA, light becomes dark and vice versa. On the Game Boy series, this makes the image have very good contrast, but the cost is that things dont look correct in terms of tone and shade.
The biversion process inverts the signal going to the LCD. This inverts the LCD in another way. However, the LCD is already inverted! To put it short, it un-inverts it by canceling it out, producing a contrast-filled display with accurate image.
To accomplish this, we will use a 74hc04 hex signal inverter chip, though just about any 5V-compatible inverter will work.
On the DMG (Original Game Boy) this is easy the LCD data signal lines have contact points, and are easy to find and wire to. But nobody has documented this for the MGB (Game Boy Pocket)! I had to do some probing and cutting, but I found it, and confirmed the data signal is identical to that of the DMG, and a video-out or in port to either model is possible (You can use a GB Pocket LCD on a DMG even!). CPU pins 45 and 46 go to pins 13 and 14 on the LCD connector, respectively. What well be doing is cutting that line, and taking the data from Pin 45 on the CPU, putting it into the 74hc04s input, and taking the output, and connecting that to the pin 13, and the same for the next pin. Heres a wiring diagram:
For the 5VDC power *pin 14 on the 74hc* I pulled VDD from C21 on the top left. GND can be found all over, I used the power switch.
So, results:
Enjoy!
Here's a much better diagram I made shortly after showing easier points to solder to:
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