[HECnet] VMS/RSX Guest accounts

[Thomas DeBellis]

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.

So, the 2020 came with a maximum of 512K words, 2**9.  An addition bit 
would have brought it up to a full megaword, 2**10, which is quite 
reasonable for the target audience (some kind of installation that 
didn't hold stock in the local power utility).

I guess there may have been modifications to the 2020 build of the 
monitor to allow for the extra bit.  I don't know if the Unibus devices 
could do DMA into the full address space.

Did you pick up any software with these little jewels?  The monitor 
changes might be interesting.

> ------------------------------------------------------------------------
> On 4/24/20 12:12 AM, Dave McGuire wrote:
>    Nice!
>
>    One of our 2020s is in the brown color scheme.  You know what that
> means: ADP, and one more address bit.
>> ------------------------------------------------------------------------
>> On 4/23/20 6:15 PM, Thomas DeBellis wrote:
>>
>> The solution for 4.1 was one of the finest hacks I have ever heard of;
>> while the 2020 doesn't support extended addressing, it does support
>> multiple address spaces, so what they did was move all the symbols into
>> a separate address space.  This was called 'hiding' symbols and I
>> thought it was great because it made them harder to smash.  However, all
>> of that went out the window with 5.0, which fully supported extended
>> addressing.
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