Jon Elson via cctalk wrote:
> On 10/11/2017 01:51 AM, Steven M Jones via cctalk wrote:
> >
> >
> >
> >
> > On 10/10/2017 12:51, allison via cctalk wrote:
> >> Memory says: it was MICROVAX/RT and the cpu had a reduced instruction
> >> set and was used with ELN/PASCAL. IT was a reduced capability
> >> machine.
> > As I recollect it used the same KA630/M7606, and any peripherals were
> > the same as other Mayflower machines. The entire gimmick was that you
> > had three fewer Q/Q slots and an RC on the badge.
> >
> > Therefore no difference in the level of ISA subsetting, but I think it
> > would have been an attractive target for VAXELN applications.
> >
> > ISTR there were later products that were limited to VAXELN, but can't
> > recall any designations...
> >
> I think it would be VERY hard to remove instructions from
> the 78032 CPU chip. You could leave out the
> floating point processor, and maybe do things with the gate
> arrays to restrict memory size and such.
>
> Jon
As far as I remember there where some restrictions in the cache memory
controller that prevented the use of virtual memory on that restricted
KA620 CPU, not the CPU chip itself.
I have an ISA Card with a "VAX-Brick" on it, but that was a later
Version with an ordinary CVAX, Cache, SCSI and Network inside w/o those
restrictions. Usually that was meant to run VAXELN.
Tried to port NetBSD to it, but failed since the NetBSD VAX Kernel is
somewhat related to a plate of spaghetti and the card firmware itself,
that uses a part of normal memory to store the boot config,
marking that memory as broken to the operating system software to
protect it from overwriting, but NetBSD does'nt take any notice of that.
The SLU was another problem..
That was a little bit to high for me.. but at least the kernel netbooted..
Regards,
Holm
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