7 Oct
2007
7 Oct
'07
1:10 p.m.
Back to 6 bits. For the type of stuff that the BDP
community did, 6
bits per character was plenty.
In that sense, using an 8 bit character was a real waste. Two 6-bit
characters can pack 3 BCD digits--exactly the same efficiency as
S/360 packed decimal--and packing/unpacking is not much different
from converting from packed to zoned decimal.
This is not what IBM found.
Back then, most of the data was BCD. Yes, 12 bits can get you 3 digits
and the same space efficiency, but then the processor has to start
dealing with non-2^n multiples of digits. A 36 bit word would give 9
BCD digits, and odd numbers are no fun to deal with.
The same 1964 (I think) report states that IBM was getting concerned
about the possibility of the alphanumeric character set expanding with
upper and lower case, symbols, etc..
--
Will