[f-cpu] Why we use a scoreboard?

[Andreas Romeyke <art1@it-netservice.de>]

Hello,

While my lecture about f-cpu there were some questions (see other
mails)...

In preparation I readed also the "Taschenbuch
Mikroprozessortechnik" (Beierlein & Hagenbruch, Fachbuchverlag Leipzig,
ISBN: 3-446-21049-0) and at page 100 I found some explanation about
Scoreboards.

There is the meaning, that scoreboards are an outdated technology and an
extension or evolution of scoreboard is the "Tomasulo"-algorithm, which
combines a reorder-buffer with elements of scoreboard to
"Reservation"-stations, that means in listelements of a ringbuffer are
saved necessary adressses and data, commit-attributes:

operation || source1 | data1 | valid1 || source2| data2 | valid2 || destination

Instructions in Reservationstations (listelements) with all validated data
could be executed by scheduler/dispatcher


Could you explain if there are significant differences and explain the
Tomasulo-algorithm a little bit clearer?

Bye Andreas

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