On Tue, 2005-05-24 at 16:11 -0400, Bob Ammerman wrote:
> What successful computer system used decimal arithmetic with numbers=20
> represented in biquinary?


Look at the hardware description on this page....
http://www.highersystems.co.uk/Leo_3.html


One feature that was was unusual (if not unique) was the ability to do
arithmetic in different bases, not just decimal or binary(hexadecimal)
but in Pounds,shillings and pence (=C2=A3.s.d) or pounds and ounces. This=
 was
achieved by having an 'excess digits'(?) register containing a constant
that was added/subtracted(if no carry) to each word before/after 'hex'
arithmetic was carried out. For example decimal arithmetic used '66666'
so that 9+1(+6) =3D '10' (hex). '=C2=A3sd'  used  '6614 6 4' (I think?) t=
o
provide for  pence (1 digit 0-11), shillings (two digits 0-19). At that
time the usage of A-F for 10 to 15 was not known and we used character
such as '=C2=A3', '#', for 12 to 15 ( there were special '10' and '11'
characters to hold 'old pence').

Peter Onion


--=20
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