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Cable & pinout

A passive 5-contact null-modem crossover between two EXT ports. No active parts. Same port and cable on mono NGP and color NGPC.

Pinout

GND is the center contact (pin 3). The two pairs either side of it are crossed.

12345 TXD0RXD0GND/RTS0/CTS0

Pin Signal Dir Crosses to peer
1 TXD0 out pin 2 (RXD0)
2 RXD0 in pin 1 (TXD0)
3 GND — pin 3 (straight)
4 /RTS0 out pin 5 (/CTS0)
5 /CTS0 in pin 4 (/RTS0)

Crossover wiring

GND straight through the center; the data pair (TXD/RXD) and flow pair (/RTS//CTS) each swap:

Console A Console B 1 TXD2 RXD3 GND4 /RTS5 /CTS TXD 1RXD 2GND 3/RTS 4/CTS 5

Port & electrical
Connector EXT port — recessed female edge slot, 5 contacts, ~1.5 mm pitch
Levels 3.3 V CMOS
Framing 19200 8N1, LSB-first, idle-high, non-inverted
Driver TMP95C061 SIO channel 0

Confirm before building a plug

GND = center contact and the crossover topology are traced facts. The exact signal on each of the four outer pins should be re-checked on your unit (multimeter continuity: GND = the pin that reads through to the shield / MBT−, then match the rest against the SIO0 pins).