Adapter; Introduction - IBM 3278 Technical Reference

Section 1. IBM Personal Computer
3278/79 Emulation Adapter
Introduction
The IBM Personal Computer 3278/79 Emulation Adapter card
supports emulation of the base 3270 data stream and controls
communication between the IBM Personal Computer and an IBM
control unit. All system control signals and voltage requirements
are provided through a 2 by 31 position card edge tab. A coaxial
connector (type BNC) joins this adapter card to the control unit.
The adapter card will accept, decode, and execute commands
issued from the control unit or the IBM Personal Computer. All
information from the control unit is sent in the form of a 12-bit
frame over a coaxiallinlc Transition checks include mid-bit
transition and transmission parity.
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