8 Apr
2005
8 Apr
'05
1:49 p.m.
Thanks, that explains things. With such weird functionality, no wonder the chip didn't
make it to the 7400 series. Perhaps it was a custom chip (maybe for those pdp8's) that
Signetics released to their general product line.
The circuitry in the Wang was misleading in that one of the uses of the chip has an
intentional but logically irrelevant (unecessary) connection to the S1 control input.
(I had to go to the cctalk archives to find these replies. I've got to get switched
over from cctech to cctalk.)
jos dreesen wrote:
my 1978 databook lists this device, and weird it is :
A input is inverting, B input is not.
if S0 is L and S1 is dont care : B to F.
If S0 is H and S1 is L : Anot to F
if S0 is H and S1 is H : F is H.
gerold pauler wrote:
They were also used in the pdp8/e/f/m.
The processor maintenance manual revealed on page A-10:
Control Input Output
C D Yn
LOW LOW Bn
LOW HIGH Bn
HIGH LOW ~An
HIGH HIGH HIGH
16 15 14 13 12 11 10 9
I--------------------------------I
I Vcc A4 B4 Y4 Y3 B3 A3 C I
DEC 8266 Pinout I
I A1 B1 Y1 Y2 B2 A2 D
GND I
I--------------------------------I
1 2 3 4 5 6 7 8