Path: utzoo!utgpu!water!watmath!clyde!rutgers!rochester!udel!gatech!dcc1!emcard!polycatt!philabs!masscomp!spook!hank
From: hank@spook.UUCP (Hank Cohen)
Newsgroups: comp.arch
Subject: Re: Wirth's challenge (was Re: RISC
Message-ID: <130@spook.UUCP>
Date: 4 Jan 88 16:12:19 GMT
References: <6901@apple.UUCP> <28200075@ccvaxa> <12181@orchid.waterloo.edu> <19825@amdahl.amdahl.com>
Reply-To: hank@masscomp.UUCP (Hank Cohen)
Organization: MASSCOMP -- Bethesda Md.
Lines: 17

In article <19825@amdahl.amdahl.com> esf00@amdahl.amdahl.com (Elliott S. Frank) writes:
>
>The Amdahl 580 (a 370-compatible [CISC] machine designed ca. 1978-79)
>was designed with contemporary 'UNIX machine' features -- separate
>I and D caches, etc. It turned out it ran 360/370 COBOL programs like
>the proverbial 'bat out of hell'.
>-- 
I always found the most interesting feature of the Amdahl 580 to be
the single cycle decimal adder in the ALU.  It was (when I last knew
the details of such things) <24nS. I believe that the CPU designers
were willing to use a lot of gates to achieve that speed.

Amdahl does a lot of simulation and analysis of their instruction
mix and is willing to design the machine to optimize certain
benchmarks.  When you run a lot of COBOL and PL/I a fast decimal adder
makes sense.  Perhaps Elliot could tell us how fast the 5890 decimal
adder is.