7 Apr
2005
7 Apr
'05
12:50 p.m.
Would someone happen to have a 1970s-era Signetics TTL handbook in which they could look
up some details about the N8266?
I know that it is a quad 2-input multiplexor/selector and I know what the pinout is.
The questions are:
- what is the specific logic functioning of the 2 control inputs?
- is there any inversion in the data path(s)?
From the cross-references I have the 8266 doesn't
seem to have made the transition to a 7400 series standard, probably because it's
functioning is a little weird.
They are used in a Wang 520 calculator with the control lines operated in two different
manners. While the intent of the circuitry would seem apparent, the two uses of the
control lines are somewhat idiosyncratic to each other.
(FWIW: the 520 is circa 1972, TTL logic, micro-program architecture, core rope
micro-program store.)
8 Apr
8 Apr
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 
7 Apr
7 Apr
1:09 p.m.
Am donderdag, 07.04.05, um 21:50 Uhr (Europe/Zurich) schrieb Brent
Hilpert:
Would someone happen to have a 1970s-era Signetics TTL
handbook in
which they could look up some details about the N8266?
I know that it is a quad 2-input multiplexor/selector and I know what
the pinout is.
The questions are:
- what is the specific logic functioning of the 2 control inputs?
- is there any inversion in the data path(s)?
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.
Jos
1:29 p.m.
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
Gerold
Brent Hilpert wrote:
Would someone happen to have a 1970s-era Signetics TTL
handbook in which they could look up some details about the N8266?
I know that it is a quad 2-input multiplexor/selector and I know what the pinout is.
The questions are:
- what is the specific logic functioning of the 2 control inputs?
- is there any inversion in the data path(s)?
From the cross-references I have the 8266
doesn't seem to have made the transition to a 7400 series standard, probably because
it's functioning is a little weird.
They are used in a Wang 520 calculator with the control lines operated in two different
manners. While the intent of the circuitry would seem apparent, the two uses of the
control lines are somewhat idiosyncratic to each other.
(FWIW: the 520 is circa 1972, TTL logic, micro-program architecture, core rope
micro-program store.)
7199
days inactive
7200
days old
4 comments
4 participants
participants (4)
-
eric＠brouhaha.com -
gerold.pauler＠gmx.net -
hilpert＠cs.ubc.ca -
jos.mar＠bluewin.ch