This part is a kind of semiconductor called MC34055.

Function of this product has IEEE 802.3 10BASE-T TRANSCEIVER.

Manufacturers : Motorola

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Some of the text within the PDF file :

Order this document by MC34055/D IEEE 802.3 10BASE-T Transceiver The Motorola 10BASE–T transceiver, designed to comply with the ISO 8802–3 [IEEE 802.3] 10BASE–T specification, will support a Medium Dependent Interface (MDI) in an embedded Media Attachment Unit (MAU)*. The interface supporting the Data Terminal Equipment (DTE) is TTL, CMOS, and raised ECL compatible, and the interface to the Twisted Pair (TP) media is supported through standard 10BASE–T filters and transformers. Differential data intended for the TP media is provided a 50 ns pre–emphasis and data at the TP receiver is screened by Smart Squelch circuitry for specific threshold, pulse width, and sequence requirements. Other features of the MC34055 include: Collision and Jabber detection status o [ ... ]

MC34055 PDF Datasheet Download