Lynx-cards sizes are : 128KB,256KB and 512KB. 1MB is also possible.

Lynx sees this cards through a port and may not address them directly, only via a counter, better two counters: one for the block (0..255 on all cards) the other for the position in the current block (0..4095, depends on card-size). The postions wraps, so the block has to be set manualy and the program/game has to know the exact card-size to allow reads of more the one block.

Ok here's the pin-out:
1 GND
2 D3
3 D2
4 D4
5 D1
6 D5
7 D0
8 D6
9 D7
10 CARD/ (this is OE/)
11 A1
12 A2
13 A3
14 A6
15 A4
16 A5
17 A0
18 A7
19 A16
20 A17
21 A18
22 A19
23 A15
24 A14
25 A13
26 A12
27 SWCON/ (this is WE/)
28 A8
29 A9
30 A10
31 Vcc
32 AUDIOIN (I/O pin but not analog, digital, for 1MBcards used)
33 Vcc
34 SWVCC

Note: A12..A19 is connected to a 74HC164 to select block
A0...A10 is connected to a 4040 to select postion
A11 is __missing__
CARD/ is strobed on reads
SWCON/ is strobed on writes