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Comment by jandrese | Hacker News Reader

It sounds puny today, but compare against the famous Commodore 64 released 3 yeas later:

    IBM: 17.2 Mhz    C64: 1.023Mhz
    IBM: 4/6/8MB RAM C64: 64kB RAM
    IBM: 64kB Cache  C64: What cache?

The IBM is a beast relative to what ordinary people could afford at the time.

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VAX-11/780 maybe a closer comparison, from the same era:

     5 MHz cycle time (1 MIPS)
     2 MB - 64 MB  RAM
     8 KB cache
     Price $120 K

I much rather use VMS or Ultrix than any IBM OS :-)

http://bitsavers.org/pdf/dec/vax/780/EK-11780-UG-001_780hwUG...

http://www.vaxhaven.com/images/0/00/EK-11780-PG-001.pdf

While I do find VMS much more understandable than MVS (it's a completely different branch of the Tree of Computing, as similar to modern PCs as the extremophiles that live next to volcanic chimneys in the bottom of the ocean are to us), I have to say the VAX competed with the much lower end machines in the 370 family. Also, you don't measure a mainframe's capacity in MIPS - The CPU is a small part of the of overall system and a lot of hardware goes to the multiple IO subsystems that offload the main CPUs so that they can keep running your applications while the rest of the system focus on pushing bits in and out of the system. It was considered a "minicomputer", in contrast to a proper computer such as the System/370.

DECSYSTEM-20 is closer to a proper mainframe. It was at least 6x faster than VAX-11/780 on a benchmark I tried in ~1987. Also TOPS-20 was the bomb!

http://gordonbell.azurewebsites.net/cgb%20files/evolution%20...

Sadly it was an anachronistic 36-bit machine with no future..

36 bits makes perfect sense if you are thinking in octal.

I don't think many VAX-11/780s were shipped with 64MB RAM, the ones I used had 2 or 4.

Cray-1 from that era had 80 Mhz clock and 8 Megabytes (1 Megaword) memory. But had peak floating point of 160 mega flops. Also, no cache. But highly interleaved main memory.

The Cray designs and the IBM mainframes were built for different requirements. The Cray machines were designed for the highest possible processor speed while mainframes were much more geared towards business needs, where you do a lot of IO and just a little bit of processing on the data, before sending it back to tape.

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