Re: The Design of Design

It appears that Thomas Koenig  <tkoenig@netcologne.de> said:

An interesting detail about the /360 design was that they originally
wanted to do a stack-based machine.  It would have been OK for the
mid- and high-end machines, but on low-end machines it would have
been undompetetive, so they rejected that approach.

The 1964 IBM Systems Journal paper has half a page on that.  They felt
it would be about as good for scientific machines, worse for commercial.
Stack machines have more compact instructions due to zero-address, but
they need more instructions to move stuff around in the stack so that
was a wash, and the performance depends on how much of the stack it
can keep in fast memory.

The 360 had way more registers than any previous IBM machine. The 7094
had accumulator, MQ, and 7 half length index registers. STRETCH had an
overcomplex architecture with 7 fast registers, mostly special
purpose. Some of the commercial machines had an odd circular store
treated as some number of variable length registers.

They had the insight to see that the 16 fixed sizs registers could be
in fast storage on high end machines, main memory on low end machines,
so the high end machines were fast and the low end no slower than a
memory-memory architecture which is what it in practice was. It was
really an amazing design, no wonder it's the only architecture of its
era that still has hardware implementations.

He discusses the book on computer architecture he co-authored with
Gerrit Blaauw in it (as a project).  Would be _very_ nice to read,
but the price on Amazon is somewhat steep, a bit more than 150 Euros.

I have a copy. The first half is the textbook, which is pretty good.
The second half is descriptions and evaluations of 30 architectures from
Babbage and the Mark I to the 6502 and 68000, which are great.

I see a used copy here for $105 which is what textbooks cost these days:

https://www.valore.com/textbooks/computer-architecture-concepts-and-evolution-1stth-edition/0201105578

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