[HECnet] VMS/RSX Guest accounts --> 2020 memory extension

[Thomas DeBellis]

Tops-20 can and did go to the full 30 bit virtual extended address 
space.  I know that a Toad can run 32KW physical memory.

I had looked into changing the KLH10 micro-engine some time ago about 
implementing the additional bits.  Those didn't appear to be too bad, 
but tedious.  The pager would have handled it with some modifications to 
the CST format.

I think the real issue would have been to change the RH20's to use 
them.  In Tops-20 itself, there are a number of had assumptions that you 
are running a maximum of 4 MW real  and 32 MW virtual.  These would need 
to be changed.

I had also been toying with the idea of implementing swapping drums 
again and using a re-baked RC10 as banked memory.  Some of the 
conditional code still exists in STG.  Unfortunately, I was unable to 
find a copy of either RS04SV or RC10SV anywhere.  I do have the TENEX 
drum sources, but I would imagine they'd need to be adapted.

Then I joined HECnet and have spent the last few months tinkering with 
DECnet.  The distribution of 7 has a number of things that needed either 
polishing or fixing.

On 4/29/20 2:15 PM, R. Voorhorst wrote:
> L.S.
>
> The memory extension from 1 --> 2-->4 MW are quite easy to implement within the 2020 KS10 architecture, few extra mapping bits in the CPU and Unibus maps are all that is needed.
> Though in current hardware maybe a bit difficult:  2 more bits in the UBA rams, etc. in Simh it is easy to do.
>   
> As Tops10 was developed onto KL10 and modified for KS10, the real limits of Tops10 was really the 4 MW barrier i.e. 13 bits versus 11 bits.
> The KS10 modifications were relatively simple to adapt to larger sizes,  BOOT inclusive.
>
> R.V.
>
> -----Original Message-----
> From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Dave McGuire
> Sent: Wednesday, 29 April, 2020 19:58
> To: hecnet at Update.UU.SE
> Subject: Re: [HECnet] VMS/RSX Guest accounts
>
> On 4/28/20 11:51 PM, Thomas DeBellis wrote:
>> You know, I have been racking my brains from time to time and I can't
>> remember a thing about the ADP modifications to the 2020.
>    I myself know very little about the specifics. (I'm mainly an -8, -11,
> and VAX guy)   I would guess Peter Lothberg knows quite a lot about it.
>
>> Did you pick up any software with these little jewels?  The monitor
>> changes might be interesting.
>    No software, unfortunately.  Just the iron.
>
>    BTW, one of our museum folk is working on the 36-bit quote swag now.
>
>            -Dave
>
> --
> Dave McGuire, AK4HZ
> New Kensington, PA
>