DEC 8640 Pinout

[Bob Smith]

SOme history that might come in handy -
pbirkel at gmail.com
March 8th, 2014, 11:37 PM
The DEC PDP-11 Unibus Handbook identifies three standard ICs for use
when connecting to Unibus lines:

Bus Receiver - 8640 Quad NOR
Bus Transceiver - 8641 Quad
Bus Driver - 8861 Quad NAND

It seems to be generally agreed that the 8861 driver/transmitter can
be substituted by the 7439 Quad 2 Input NAND Buffer O.C.

There seems to be no recognized physical substitute for the 8640, at
least in part because it uses the 1 & 8 pins rather than 7 & 14 pins
for GND/VCC, respectively (see Figure 1-25). Is that correct? What
have folks been doing when needing to physically replace one of these
-- substitute from a sacrificial module?

For new designs, or rewiring old ones (dead-bug?), is there a
generally agreed logical substitute for the 8640?

Unibus handbook Figure 1-30 does specify the RC-equivalent input for
this IC but I have not as yet tried to cross-walk it against
well-known SN74xx-series chips. I imagine that I'm the umpteenth
person to encounter this problem, so before I try to rediscover fire
I'm hoping that someone else could share their torch of knowledge :->?
On Sun, Oct 28, 2018 at 2:19 PM Camiel Vanderhoeven via cctalk
<cctalk at classiccmp.org> wrote:
>
> 8640 looks like a date code; most dec chip numbers begin with "DC".
>
> On 10/28/18, 6:53 PM, "cctalk on behalf of Rob Jarratt via cctalk" <cctalk-bounces at classiccmp.org on behalf of cctalk at classiccmp.org> wrote:
>
>     I am trying to trace the reason why the CPU on my Pro 350 is apparently
>     being constantly reset. I have reached a DEC 8640 chip. Does anyone have a
>     pinout for it, perhaps even a datasheet, so I can understand what it is
>     supposed to do and whether the pin is an input or an output?
>
>
>
>     Thanks
>
>
>
>     Rob
>
>
>
>