Below is from the Arnold V specs: ROM CARTRIDGE: 2 pcs 2 x 9 way 2.5mm pitch sockets. 1a A10 2a A2 1b The CPC+5V 2b +5V 3a *CE 4a A1 3b CLK 4b CA18 5a D7 6a A0 5b CA16 6b CA17 7a D6 8a D0 7b CA15 8b CA14 9a D5 10a D1 9b A12 10b A13 11a D4 12a D2 11b A7 12b A8 13a D3 14a SIN 13b A9 14b A9 15a CCLR 16a GND 15b A5 16b A11 17a GND 18a GND 17b A4 18b A3however, that seems to be nonsense/GX4000 has a female 2x18 pin cart-edge connector for [[GX4000_cartridge|cartridges]]... or maybe an internal connector?
As seen In the schematics, the pins are numbered A1..A18 and B1..B18. However, the text layer on the photos at cartridge PCBs typically uses a different numbering: 1..36 (with even numbers on the solder side of the cartridge) (and with numbers ordered in opposite direction): component side solder side 1 B18 VCC 2 A18 VCC 3 B17 CLK4 4 A17 CA18/LK2 5 B16 CA16 6 A16 CA17/LK4 7 B15 CA15/LK6 8 A15 CA14 9 B14 A12 10 A14 A13 11 B13 A7 12 A13 A8 13 B12 A6 14 A12 A9 15 B11 A5 16 A11 A11 17 B10 A4 18 A10 A3 19 B9 A10 20 A9 A2 21 B8 /CE 22 A8 A1 23 B7 D7 24 A7 A0 25 B6 D6 26 A6 D0 27 B5 D5 28 A5 D1 29 B4 D4 30 A4 D2 31 B3 D3 32 A3 SIN 33 B2 CCLR 34 A2 GND 35 B1 GND 36 A1 GND * The SIN,CCLR,CLK4 pins are special signals for the [[GX4000_cartridgeACID]], chip. Cartridges won't work without ACID. * Note: Arnold V specs say that "ROM CARTRIDGE: 2 pcs 2 x 9 way 2.5mm pitch sockets." This seems to be nonsense (or might refer to an internal connector on the cartridges have mainboard). The external cartridge connector has 2x18 pins - not 2x2x9 pins.