Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site watcgl.UUCP
Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.audio
Subject: Re: Floating Point CD's - (nf)
Message-ID: <250@watcgl.UUCP>
Date: Sun, 28-Oct-84 16:50:24 EST
Article-I.D.: watcgl.250
Posted: Sun Oct 28 16:50:24 1984
Date-Received: Mon, 29-Oct-84 02:18:28 EST
References: <1753@inmet.UUCP>, <565@watdcsu.UUCP>
Organization: U of Waterloo, Ontario
Lines: 11

Arghh!  Using hexadecimal-base floating point, as in the IBM S/360 and
its successors, is the least efficient way to use the bits in a word.
The reason is that, on the average, two of the mantissa bits will be
zero and carrying no useful information at all.  Binary-base floating
point, particularly if the always-1 leading bit is not stored, is most
efficient.  If this seems unclear, talk to any numerical analyst.

And you need 8 bits of exponent only if you want to cover a fairly wide
"dynamic range" of numbers, about 10^77.  An audio dynamic range of 120dB
is a 10^6 range of voltage levels, which needs somewhere between 4 and 5
bits of exponent.  Four might be enough.