Wikipedia: History of Binary Coded Decimal

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Changed: 14c14

While BCD is wasteful (3/8 of the available memory is wasted, even in packed BCD), it has a direct correspondence to the ASCII character set if the BCD number is prepended or OR'd with 00110000 (decimal 48), and large numbers can easily be displayed on 7-element displays by splitting up the nibbles? and sending each to a different character (the individual characters often have the wiring to display the correct figures). The BIOS in PCs usually keeps the date and time in BCD format, most probably for historial reasons.

While BCD is wasteful (3/8 of the available memory is wasted, even in packed BCD), it has a direct correspondence to the ASCII character set if the BCD number is prepended or OR'd with 00110000 (decimal 48), and large numbers can easily be displayed on 7-element displays by splitting up the nybbles and sending each to a different character (the individual characters often have the wiring to display the correct figures). The BIOS in PCs usually keeps the date and time in BCD format, most probably for historial reasons.

	Revision 12 . . August 22, 2001 1:03 am by Lee Daniel Crocker [Changed back to "nybble", which was correct the first time.]
	Revision 11 . . August 21, 2001 8:23 am by (logged).111.131.xxx *[changed 'nybbles' to 'nibbles']**