[Info-vax] Attn VSI employees: Viable full system Itanium emulator for VMS ?

[Arne Vajhøj]

On 2/20/2022 10:42 PM, Dave Froble wrote:
> On 2/20/2022 3:31 PM, Bill Gunshannon wrote:
>> On 2/20/22 13:44, Hans Bachner wrote:
>>> Arne Vajhøj schrieb am 20.02.2022 um 02:10:
>>>> On 2/19/2022 1:05 PM, John Reagan wrote:
>>>>> On Friday, February 18, 2022 at 10:36:48 AM UTC-5, Bill Gunshannon 
>>>>> wrote:
>>>>>> On 2/18/22 09:12, John Dallman wrote:
>>>>>>> In article <69d0b812-0d53-42b6... at googlegroups.com>,
>>>>>>> xyzz... at gmail.com (John Reagan) wrote:
>>>>>>>> On Thursday, February 17, 2022 at 2:28:46 PM UTC-5, Bill Gunshannon
>>>>>>>>> I can't understand the interest in HP-UX at all. It's just
>>>>>>>>> another proprietary Unix and not really one of the better ones.
>>>>>>>> Big endian
>>>>>>>
>>>>>>> What makes big-endian attractive to end-user organisations?
>>>>>>>
>>>>>>> John
>>>>>> What real difference does endianess make to anyone today?
>>>>>>
>>>>> <Fortran COMMON blocks enters the chat>
>>>>>
>>>>> Nobody has used a COMMON block in one place with an integer and in 
>>>>> another
>>>>> with bytes?  Or a C union or a Pascal variant record?
>>>>
>>>> I would use EQUIVALENCE and not COMMON for that, but it could be done
>>>> with COMMON.
>>>
>>> EQUIVALENCE is usually used when you need access to both definitions 
>>> within
>>> the same program unit. (Named) COMMON can be used to use different 
>>> definitions
>>> for the same memory area in different program units.
>>
>> Using different COMMON block definitions for the same COMMON block
>> in different parts of the same program is usually considered very
>> bad practice and can result in some rather weird and very hard to
>> track down problems.
> 
> Why?
> 
> All a COMMON block is, is a piece of memory.  Isn't it possible to want 
> to look at it in different ways?

It is error prone, because there is no check of consistency and a it
requires a search to find the instances.

EQUIVALENCE is local and therefore very visible.

Arne