From: arne@vajhoej.dk

On 9/16/2025 4:47 PM, David Wade wrote:
> On 16/09/2025 18:46, Simon Clubley wrote:
>> Especially given that z/OS is actually several years older than VMS
>> and is still going very strongly indeed.
>
> I don't believe its as strong as you believe. Perhaps the Z platform is,
> but z/OS is pretty much limited to traditional big banks and airline
> reservation systems. These systems are all much larger that most VMS
> systems so migration away is harder and riskier.

I am not sure that the attrition rate for z/OS is less than for VMS.

But they started at a way higher point, so they are still at a higher
point.

> Another notable feature of Z hardware is the virtualisation technology
> inherent in the "hardware". So it all comes with multiple Logical
> PARtitions or LPARs which despite their name are more like physical
> partitioning of the hardware, and zVM which uses the "Start Interpretive
> Execution" (SIE) instruction to create Virtual Machines.
>
> DEC never had anything like this.

I always considered Alpha Galaxy to be somewhat similar to LPAR.

Arne

--- SoupGate-Win32 v1.05
 * Origin: you cannot sedate... all the things you hate (1:229/2)