Quad line receiver, active production
The SN55189AJ is a quad line receiver from Texas Instruments — four independent RS-232 receivers in one DIP package, designed to convert RS-232 voltage levels to TTL-compatible logic levels on the receiving end of a serial link.
Bulk package, field-swappable
Shipped in bulk — loose tubes or trays, not tape-and-reel — which means it arrives in a standard DIP-compatible format that a technician can handle without a pick-and-place machine. The DIP footprint is socket-friendly: on a customer site with a basic extraction tool, this receiver swaps in minutes without a hot-air station or reflow profile. Orientation is obvious from the pin-1 notch, so a field swap is low-risk even without a schematic in hand.