[Info-vax] VMS Software Q1 '23 Update

[Dave Froble]

On 1/29/2023 10:42 AM, Arne Vajhøj wrote:
> On 1/29/2023 9:32 AM, Scott Dorsey wrote:
>> =?UTF-8?Q?Arne_Vajh=c3=b8j?=  <arne at vajhoej.dk> wrote:
>>>
>>> I sort of had guessed that word was the same as on VAX,
>>> but I don't understand how it can't have a 32 bit integer.
>>>
>>> How does one work with file sizes and file position
>>> in bytes on PDP-11?
>>>
>>> I know you don't do C, but I believe C was invented on
>>> PDP-11.
>>
>> I think the issue is with the programming language and not with the
>> architecture.  And yes, you can use bignum in C, at least under v7 Unix,
>> and store really really big numbers.
>
> So other language & OS combinations did support 32 bit
> integers on PDP-11?
>
> Possible including first version of C.
>
> Arne
>
>

When was C first available?

The problem was, in 1974, we had RSTS/E and Basic+ on PDP-11.  That was what was 
available.  Sure, in later years, there were more options.  As far as that goes, 
we developed what we called "double integer", which was two word integers, used 
in memory as D-float, and stored as a 4 byte string.  6 variations gave us whole 
integers, and 5 variations with 1 to 5 digits after the decimal point.  The max 
values were still limited to I believe 8 digits.

What was developed worked.  Later, when discussing with customers the choice of 
using newer capabilities, they asked, "what's the benefit" and actually what 
they had was working.  They were not interested in paying to replace something 
that was working for them.  There was also the issue of running the programs on 
historical data saved on tape.  They were not interested in converting the 
historical data.

And so the old capabilities remained in use, and they did the job.  They are 
still doing the job.

-- 
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef at tsoft-inc.com
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