Pascal not considered harmful - was Re: Rich kids are into COBOL

[Chuck Guzis]

On 02/21/2015 08:25 PM, Eric Smith wrote:

> Having short, int, and long types that occupy 64 bits of storage but
> only effectively have 48 bits of integer value is perfectly fine, but
> it does have some consequences that must be considered.

The reason I asked was because of the Seymour Cray/Jim Thornton 
philosophy on design.  I don't know if this is reflected in the Cray 1, 
but it certainly is the case in the CDC 6000-7000 series as well as the 
STAR/Cyber 200/ETA-10 line.

The 6000/7000 machines have a long add (60 bit) unit, but no integer 
multiply/divide unit--it's possible to perform a multiply or divide 
yielding a 60-bit integer, but it's a bit involved and generally not 
done.  So significance on integers is limited to 48 bits out of 60.

The Cray 1, of course, didn't even have a divide unit--just a "floating 
point reciprocal approximation" instruction.

The Cyber/STAR goes a bit farther in not mentioning the word "integer" 
at all and divides the 64 bit word into two parts--the exponent/length 
high-order part of 16 bits and the significand/index part of 48 bits. 
Any integer operations are conducted as "index" operations and the sign 
bit is bit 47.  Period--no 64 bit integers at all.  Bit-logical 
operations operate on the entire 64 bit word. Double-precision floating 
point is the pretty much the same on both 60 and 64-bit systems--an 
upper and lower floating point part, each being a complete floating 
point number with exponent.  No integers per se.

I know there was a C for the ETA units, but I don't know if a C existed 
for the 60-bit machines.   But it wouldn't surprise me if it did.

--Chuck