 |
 |
The IBM 1620, first as the mod I, later as the mod II, ca. 1959-60, used decimal digits, with flag bits to mark the left end of a field. Addresses were decimal, from 0 to 59999. Floating point was first done in software, with separate exponent field, although one implementation, PDQ Fortran, derived from Fortran with Format, used excess-50 notation, using a single field for the number and the left-most two digits comprising the exponent. PDQ was about three times faster in execution, but later addition of hardware floating point removed that advantage. Of course the 360 soon removed the 1620. RAR -----Original Message----- From: Fortran 90 List [mailto:[log in to unmask]]On Behalf Of [log in to unmask] Sent: Wednesday, March 10, 2004 4:46 PM To: [log in to unmask] Subject: Re: Data type "UNDEFINED" Loren P Meissner asked: > And I think in the early days, the "word" occupied by a default integer > was usually the smallest addressable storage unit. (Was IBM 360 the > first byte-addressable machine?) If by "byte addressable" you mean "less than 16 bits" the answer is no. The IBM 1401 had 6-bit characters, with "word mark" bits to delineate fields. I have the manual for the 1401 Fortran compiler. Pre-360 successors to the 1401 included the 1460, 1440, 1410 and 7010 (or was it 7070?) The 1480 was planned but then not built with that label. Somebody told me it became the 360/20. Honeywell had a competitor for the 1400 series called the 200. The Univac 1005 was also a character-addressable machine. The NCR 315 (actually built by CDC) allowed addressing 4-bit BCD digits, 6-bit characters or 12-bit integers that they called "slabs". Of the machines that had good-size integers and floating-point hardware, it is possible the 360 was the first to include byte addressing. -- Van Snyder | What fraction of Americans believe [log in to unmask] | Wrestling is real and NASA is fake? Any alleged opinions are my own and have not been approved or disapproved by JPL, CalTech, NASA, Sean O'Keefe, George Bush, the Pope, or anybody else. ----------------------------------------- *****************Internet Email Confidentiality Footer****************** Privileged/Confidential Information may be contained in this message. If you are not the addressee indicated in this message (or responsible for delivery of the message to such person), you may not copy or deliver this message to anyone. In such case, you should destroy this message and notify the sender by reply email. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of The Shaw Group Inc. or its subsidiaries shall be understood as neither given nor endorsed by it. ________________________________________________________________________ The Shaw Group Inc. http://www.shawgrp.com