16 Oct
2000
16 Oct
'00
2:34 p.m.
-----Original Message-----
Mega thanks, that makes some sense looking at the board.
I'd suspected something like that. Te ability to start on any
4k boundary is nice. The 74138 on one side and the '20 on
the other should have screamed at me.
Allison
The 16 pin DIP socket has a "black box"
plugged into it. Hmm, popping
that box open reveals the expected jumpers.
Looking down at the jumpers, the upper left corner is pin 1, upper right
is pin 16, I have 4 wires installed:
pin 5 - pin 14
pin 6 - pin 13
pin 7 - pin 12
pin 8 - pin 11
My board is set to cover fields 4 - 7.
My guess would be that the 3 EMA bits are decoded into 8 lines, and are
present on pins 1 - 8, corresponding to DEC field terminology 0 - 7,
which makes obvious sense since pins 1 - 8 are on one side of the
DIP jumper, and that pins 11 - 14 are the individual 4Kx12 field
select jumpers.
-Lawrence LeMay