29 Apr
2020
29 Apr
'20
5:51 a.m.
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.
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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.