Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: Notesfiles $Revision: 1.7.0.5 $; site uiucdcsb Path: utzoo!watmath!clyde!cbosgd!ihnp4!inuxc!pur-ee!uiucdcsb!seefromline From: dollas@uiucdcsb.Uiuc.ARPA Newsgroups: net.arch Subject: Re: Floating pt. A/D converter Message-ID: <5600033@uiucdcsb> Date: Thu, 11-Jul-85 22:30:00 EDT Article-I.D.: uiucdcsb.5600033 Posted: Thu Jul 11 22:30:00 1985 Date-Received: Sat, 13-Jul-85 08:39:32 EDT References: <293@eneevax.UUCP> Lines: 32 Nf-ID: #R:eneevax.UUCP:-29300:uiucdcsb:5600033:000:1532 Nf-From: uiucdcsb.Uiuc.ARPA!dollas Jul 11 21:30:00 1985 To the best of my knowledge there is no such thing as a floating point A/D converter. The job of an A/D converter is to resolve an analog signal within a range to a binary number. Usually 16 or 18 bits are about as good as you can get (and on top of that I claim that even if you had more bits of accuracy there would be little use for them since the signals you are most likely to digitize are not that accurate, there is noise, etc). With these 16 or 18 bits you can convince yourself that the IEEE floating point format is an overkill, even if you decide to only use the mantissa part of it. Since for the computational part (or for any other reason) you want to use the IEEE format, if all the chips you use are of the same family (ie compatible) you can set all the bits of the exponent to the value that is effectively zero (that would be 127 due to the exponent bias I think) and use the bits of your A/D as the most significant digits of the mantissa (and hardwire the rest to logical 'zero'). Here you see that if you want to change the offset of the range you can do it hardware-wise, or in the software. As a last remark, there may be out there a format converter chip that translates a weighted binary number to IEEE standard format; I do not know of the existence of such a chip, maybe other netters do however. Good Luck! Apostolos Dollas U of Illinois Dept. of Computer Science USENET: ...!{pur-ee,ihnp4}!uiucdcs!dollas CSNET: dollas%uiuc@csnet-relay.arpa ARPA: dollas@uiuc.arpa