18 Sep
2015
18 Sep
'15
6:43 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
duell
Sent: 18 September 2015 14:33
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Subject: RE: Self modifying code, lambda calculus - Re: ENIAC programming
>
> > Are there any computers that do let you put microcode into RAM
> > now-days.
>
Of course not sure if it's a stage further or a stage less, but any way, but
for any FPGA implementation of a computer, and there are many about, then
the entire system definition is stored in RAM which is loaded at power-on...
"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 the next room) have 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