[Info-vax] VMS Software Q1 '23 Update

[Simon Clubley]

On 2023-01-29, Arne Vajhøj <arne at vajhoej.dk> wrote:
> On 1/29/2023 1:21 AM, Dave Froble wrote:
>> On 1/28/2023 10:44 PM, Arne Vajhøj wrote:
>>> On 1/28/2023 10:39 PM, Dave Froble wrote:
>>>> On 1/28/2023 8:28 PM, Scott Dorsey wrote:
>>>>> One of the absolute FIRST things that I was told about floating point
>>>>> variables in my first programming class was to NEVER use them to 
>>>>> represent
>>>>> money.
>>>>
>>>> What if you didn't have a choice?
>>>>
>>>> RSTS/E V04b
>>>>
>>>> Signed word integers
>>>> Strings
>>>> Single and double D-float
>>>>
>>>> That's all there was ...
>>>
>>> There is always integers and implied decimal.
>>>
>>> Not fun though.
>>>
>>> And one need an integer with enough bits ...
>>>
>>> Could PDP-11 do 32 bit integers?
>> 
>> What part of "signed word integers" didn't you understand?  As in 16 
>> bits. -32768 to 32767.
>
> 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?
>

The same way as it's done with a block-based filesystem (ODS-2) on VMS.

In general, the 16-bit nature of the PDP-11 is reflected in the API.

Ever worked with real-mode MS-DOS at assembly language level ?

It's the same kind of thing.

> I know you don't do C, but I believe C was invented on
> PDP-11.
>

What makes you think that "int" in C is _always_ at least 32 bits ? :-)

There's a reason why both int and long int have always existed in C.

And on architectures that do not support 32-bit ints, then long int is
a library/RTL feature implemented by the language in the same way as
64-bit long long int is implemented by the language RTL on 32-bit
architectures.

Also, most languages on RSTS/E intended for commercial data processing
also supported a decimal datatype, which was implemented by the language's
RTL. It seems early RSTS/E Basic wasn't one of them however, based on
what David is saying.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.