AT&T 3B2/300 Technical Reference Manual page 405

FUNCTIONAL D E S C R I P T I O N - - - - - - - - - - - - - - - - - - - - - - - - - - -
Data and Check Signals
The data bus includes 32 data bits (MD31-00[0]) and 12 bits of half-word modified Hamming
check (MCBll-0[0]). The Hamming bits, along with the error detection and correction circuitry in the
memory controller, allow double-bit error detection and single-bit error correction in each half-word of
memory. The relationship of the check bits to the data bytes is shown in the following table.
MCBll-06[1] MCBOS-00[1]
MD31 - 16[1] MD15 - 00[1]
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