6 Dec
2008
6 Dec
'08
1:58 p.m.
Philipp Hachtmann wrote:
I have the following stuff:
G104 X/Y drivers
G227 Sense/Inhibit
G619A 4K core stack
The 4K stack is broken and lost forever.
But I have a spare G646C "4K or 8" Stack sitting around.
I *think* it has 8K.
Does anyone know if I could use that stack with the rest of the package,
using only 4K of the memory?
Does anyone have schematics for the 8K core system? In my documentation
I have only information about the 4K system.
On Doug Jones' module list, there are mentioned 4K and 8K sense/inhibit
boards. And there are mentioned X/Y driver boards, without 4K or 8K
written on them.
I would like to know how DEC expanded the core. Doubling X or Y lines
would be the easiest. But why should that result in different
sense/inhibit circuitry? The sense/inhibit connections look quite
similar on both of my stacks...
Or does everything change?
Thanks for clarification :-)
And if someone has a spare 4K stack, please contact me!
The same for 8K sense/inhibit and X/Y drivers.
There was a technique called "anti-coincident addressing" that permitted the
address space to be doubled without additional X/Y/inhibit drivers or sense
amplifiers. All that was required was a little additional logic in the address
decoding/selection and the additional cores. See
http://www.cs.ubc.ca/~hilpert/e/coremem/index.html#anticoincidence .
I'm not familiar with the DEC boardsets you're referring to but it's
conceivable this technique was used to produce a 4K/8K combination boardset in
some form.