Sujet : Re: millicode, extracode, fractional PCs
De : findlaybill (at) *nospam* blueyonder.co.uk (moi)
Groupes : comp.archDate : 02. May 2025, 20:00:26
Autres entêtes
Message-ID : <m7kj2aFo79fU1@mid.individual.net>
References : 1 2 3 4 5
User-Agent : Mozilla Thunderbird
On 02/05/2025 18:26, John Levine wrote:
According to moi <findlaybill@blueyonder.co.uk>:
On 02/05/2025 16:18, EricP wrote:
>
And a paper on IBM Millicode which is kind of like Alpha PAL code
and may be similar to Robert's mega-ops.
>
The What and Why of System z Millicode 2012
https://share.confex.com/share/119/webprogram/Handout/Session11773/The%20What%20and%20Why%20of%20System%20z%20Millicode%20-%20%2311773.pdf
>
Thanks for that reference.
>
I struggle to see how "millicode" differs in essentials from
the "extracode" implementation of complex orders on the
Ferranti Orion & Atlas, or the ICT 1900 Series, of 60 years ago.
It looks very similar. The main difference I can see from extracode
is that extracode used the same hardware instruction set as normal
programs but millicode has a few extra instructions not usable
in normal programs.
So has extracode on the Orion and the 1900 Series.
Given that that deck credited Wilkes for microcode in the 1950s I'm
suprised they didn't mention extracodes. Surely they knew about it.
Quite so.
-- Bill F.
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