I did this this afternoon. I thought I might come in handy for those doing the CV BIOS mod. I've checked and doublechecked this, but if FABombjoy, John Soper, DoubleDown or anyone else want to double check it for me that would be great!
Note- cartridge slot (CS) is numbered according to IC numbering designation, assuming same orientation as BIOS eeprom.
Note- U20 has inverted orientation to most other board ICs. This guide uses accurate numbering for that IC.
BIOS eeprom pin Destinations
1 - 5V
2 CS-27
3 CS-3
4 U6-3, CS4
5 U6-2, CS5
6 - U3-3, CS7
7 U3-4, CS8
8 U3-7, CS10
9 U19-19, CS11
10 CS12
11 U3-14, U19-18, CS13, U20-10
12 U3-13, U19-17, CS14, U20-11
13 CS15, U20-12
14 C89 (ceramic cap)
15 U19-15, CS17
16 U19-14, U4-14, CS18, U20-13
17 U19-13, U4-13, CS19
18 U19-12, U4-12, CS20
19 U19-11, U4-11, CS21
20 WJ4, U5-15
21 CS23
22 WJ4, U5-15
23 WJ5, CS22
24 U4-15, CS28
25 U4-16, CS29
26 5V
27 5V
28 5V
If this checks out, it could be a good addition to the Knowledge base.