[Info-vax] VMS Software Q1 '23 Update

[Arne Vajhøj]

On 1/29/2023 11:52 AM, Dave Froble wrote:
> 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.
> 
> When was C first available?

1972, Version 2 Unix, PDP-11.

> 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.

Didn't VAX to Alpha migration cause some issues with D floating?

If I remember correct then Alpha did not fully support D.

Arne