Self modifying code, lambda calculus - Re: ENIAC programming

Diane Bruce db at
Fri Sep 18 08:45:37 CDT 2015

On Fri, Sep 18, 2015 at 01:33:05PM +0000, tony duell wrote:
> > 
> > > Are there any computers that do let you put microcode into RAM
> > > now-days.
> > 
> > "Now-days"?  There are some that do that, some of which are still in
> > operational shape.  Some VAXen, in particular, have something called
> > "writable control store", which is essentially microcode RAM.
> As far as I know, the VAX11/730 (There is one next to me waiting for me to have time
> to restore it) has the microcode entirely in RAM. Classic PERQs (3 in the next room) have

The PDP-11 console loads the microcode from disk then mostly just sits there
looking pretty whilst the VAX runs.

> their microcode entirely in RAM too (in that case, there is a microcode boot ROM to load
> the microcode from disk, but it is switched out after the microcode is loaded).
> -tony

-- Diane
- db at db at

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