HP 40290-60008 - Loopback connector - For 50-pin RS-422 connector - For testing all ports on the RS-422 ATP 37/M PC board Retail
HP 40290-69041 - RS-232C advanced terminal processor (ATP 37/M) board - Has 50-pin connector on rear - RS-232C Advanced Terminal Processor (ATP 37/M) Board (Standard) - Has 50 Pin Connector on Rear (for Attaching Cable to External Connector Panel) Retail
HP 8120-6195 - RS-232C serial interface cable - 62-pin (M) to eight 3-pin (F) ATP RS-232C connectors - 3.0m (9.8ft) long Retail