29 Oct
2008
29 Oct
'08
10:39 p.m.
Pete Turnbull wrote:
On 29/10/2008 19:52, Rick Bensene wrote:
Agreed, looks like the upper 21st 'plane' is just a header for the address wires.
I had arrived at y=48 from looking at the blurry numbers on the Y
connector on photo 5, but a recount indicates 50.
That left me wondering where the 4 connections for the sense and inhibit
wires are: looking again at the other photos, it appears there are two extra
pins on *each* axis (42 & 52) of each plane, so 4 extra pins per plane.
(In photo 4, looking down the planes starting at the left end of the row of
yellow wires one can see the cut-off wires soldered to the pins of what should
be either the sense or inhibit lines.)
I agree with Brent's analysis. I too counted
21 planes, which seems a
bit odd, as typically each plane represented one bit in a word
structure, which would indicate a 21-bit word...not something that
matches up with commonly-used word sizes in 50's/60's era computers (12,
16, 18, 20, 24, 32, 36, 48, 60 or 64 bits).
It looks pretty intact, and I don't think anything's been stripped.
However, while I count 21 layers (image 2 and image 4) in the
construction, the top layer has no cores (plain to see in images 3 and
4), so there are 20 planes by my reckoning.
And counting rows and columns of cores (not just the wires), I see 40 x
50 (you can easily count them in image 4), which matches the X and Y
numbering on the connectors. So I still reckon that stack is 2000 words
x 20 bits.