From: "John W. Kennedy" <jwkenne@...>
Date: 2004-05-13T12:08:52+09:00
Subject: Re: Major Addition Bug?

Lloyd Zusman wrote:
> Well, the IBM mainframes from the 1960's had decimal arithmetic hardware
> built in.  They could do fixed point (integer), floating point, and
> decimal arithmetic via CPU instructions.
> 
> In fact, they even had several different internal formats for the
> numbers used in decimal arithmetic.
> 
> COBOL and PL/I compilers from back then could use this CPU capability
> directly for calculations.
> 
> Do more modern chunks of Big Iron still have built-in packed and zoned
> decimal arithmetic hardware?

Yes.  The zSeries, following the S/390, following the S/370, continues 
to be compatible with the S/360.

However, these are (and always have been) fixed-point, not 
floating-point.  Decimal arithmetic is only important for accounting, 
and accounting tasks don't want floating-point, but scaled fixed-point.

Some pre-360 machines used exclusively decimal arithmetic, such as the 
702/705/7080 series, the 650/7070/7072/7074 series, the 1401/1440/1460 
series, the 1410/7010 series, the 350, and the 1620.  Some of these 
machines were designed for accounting.  Others were designed to be cheap 
and easy to program in assembler language or direct machine language. 
None were designed for speed.

-- 
John W. Kennedy
"...when you're trying to build a house of cards, the last thing you 
should do is blow hard and wave your hands like a madman."
   --  Rupert Goodwins