Re: Explaining single level store to non i people

["Hans Boldt" <hans@xxxxxxxxxx>]

Bill wrote:
> It's Monday morning and I've only had two cups of coffee, so I'm sure
> its my problem, but please explain:
>
>    For the iSeries to grow beyond the 16MB space limitation
>    while maintaining the SLS architecture, it needs
>    a CPU that supports >64-bit addressing.
>
> 16MB requires only 24-bit addresses, which is why S/370 could fit
> an instruction and an address in a 32-bit word.
> Why are you saying 64 bits are needed?

Bill: Don't forget that, on the iSeries, the 64 bits are used to address
everything on the system. That's basically what the single-level store
means. So, out of a 64-bit address, some of those bits address the object,
other bits address a location within the object.

I don't know what kind of work would be involved for addressing on the
iSeries to go "above the line" within the constraints of the single-level
store. But I would guess that if it were easy, it would have been done
long ago.

Cheers! Hans