Several different representations of bi-quinary coded decimal have been used by different machines. The two-state component is encoded as one or two bits, and the five-state component is encoded using three to five bits. Some examples are:
The IBM 650 uses seven bits: two bi bits (0 and 5) and five quinary bits (0, 1, 2, 3, 4), with error checking.
Exactly one bi bit and one quinary bit is set in a valid digit. The bi-quinary encoding of the internal workings of the machine are evident in the arrangement of its lights – the bi bits form the top of a T for each digit, and the quinary bits form the vertical stem.
The Remington Rand 409 has five bits: one quinary bit (tube) for each of 1, 3, 5, and 7 - only one of these would be on at the time. The fifth bi bit represented 9 if none of the others were on; otherwise it added 1 to the value represented by the other quinary bit. The machine was sold in the two models UNIVAC 60 and UNIVAC 120.
The UNIVAC Solid State uses four bits: one bi bit (5), three binary coded quinary bits (4 2 1)456789 and one parity check bit
The UNIVAC LARC has four bits:10 one bi bit (5), three Johnson counter-coded quinary bits and one parity check bit.
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Ledley, Robert Steven; Rotolo, Louis S.; Wilson, James Bruce (1960). "Part 4. Logical Design of Digital-Computer Circuitry; Chapter 15. Serial Arithmetic Operations; Chapter 15-7. Additional Topics". Digital Computer and Control Engineering (PDF). McGraw-Hill Electrical and Electronic Engineering Series (1 ed.). New York, US: McGraw-Hill Book Company, Inc. (printer: The Maple Press Company, York, Pennsylvania, US). pp. 517–518. ISBN 0-07036981-X. ISSN 2574-7916. LCCN 59015055. OCLC 1033638267. OL 5776493M. SBN 07036981-X. ISBN 978-0-07036981-8. ark:/13960/t72v3b312. Archived (PDF) from the original on 2021-02-19. Retrieved 2021-02-19. p. 518: […] The use of the biquinary code in this respect is typical. The binary part (i.e., the most significant bit) and the quinary part (the other 4 bits) are first added separately; then the quinary carry is added to the binary part. If a binary carry is generated, this is propagated to the quinary part of the next decimal digit to the left. […] {{cite book}}: ISBN / Date incompatibility (help) [1] (xxiv+835+1 pages) 0-07036981-X07036981-X ↩
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