1 Aug
2025
1 Aug
'25
9:26 a.m.
How available, as NoS rather than pulls, are K559IP1 and its chums 2 & 3 ?
Martin
-----Original Message-----
From: Holm Tiffe [mailto:holm@freibergnet.de]
Sent: 01 August 2025 10:45
To: Martin Bishop <mjd.bishop(a)emeritus-solutions.com>
Subject: Re: [cctalk] Q about DS3881, N8881 DEC8881..
Martin Bishop wrote:
The 8881 data sheet you reference is identical to the
one I found last night, quicker to search than rummage.
ok.
The closest it comes to an output drive specification
is in the test conditions for the "0" output voltage. The 17 ma current with 5v
supply and 0v4 Vol limit suggests a 270R test load. This is interestingly different from
the Qbus use case of 178/383 termination; the Thevinin equivalent being 120R at 3v4 -
equivalent to ~25 mA to pull down to 0v4. And, ~22 mA to pull down to 0v8 - the Lo
voltage you require, 0v4 being what you would like.
Yes, I've read that.
I am extremely sceptical that bus currents of 70/80 mA are likely, to get 70 mA you need
a Thevinin R of ~40R ie three terminators in parallel (61 / 131); many years ago, I could
not get two backplane systems to do reliable DMA - never mind three ... However, its in
the spec so everyone wants one ... Similarly, getting down to 0v4 with a realistic NPN is
a joke, under 0v8 yes but with a Q-bus as load my expectation is only a bit below 0v6.
..german saying "you are heavy on the wood way! (Du bist schwer auf dem Holzweg..yes,
I know english for runnaways (englisch für Fortgeschrittene = nonsense))
Thy don't specify bus currents with 70mA, they specify the maximal Output low current
that the device could handle ..which has almost nothing todo with the current in the use
case Unibus or Qbus.
If you can obtain K559IP1 I suggest you test them on the bench, they could well be
usable. But, yes, the well of old parts is drying out. And, IMHO, some of the
requirements in the specs are more what DEC would have liked rather than what they could
source.
I already have some on stock and.. I own an russian 11/03 equivalent Elektronika E60 with
M2 CPU .. worked 5 years before now, stored sine then. As far as I remember the K559IP1 is
used there on some boards, and The Bus is a QBUS ..but with metric dimensions even on the
connectors.
If you are interested here are som pics from the boards:
https://www.tiffe.de/Robotron/PDP-VAX/E60/
The Interface Board I4vers3 (И4ред3 in the upper left) E60-06.jpg for the russian RX02 has
an K559IP1 (К559ИП1) on the bus side, but nmostly used in this machine are K559IP2 and 3
..8640 and 8641.
So there is no need to test those chips, I know they are working.
E60-01.jpg and E60-02.jpg are the CPU Board M2.
Regards,
Holm
BTW: why off-list?
[DrB] Your 01 0906Z Aug 25 (below) was off list ...
Best Regards
Martin
-----Original Message-----
From: Holm Tiffe [mailto:holm@freibergnet.de]
Sent: 01 August 2025 09:06
To: Martin Bishop <mjd.bishop(a)emeritus-solutions.com>
Subject: Re: [cctalk] Q about DS3881, N8881 DEC8881..
Martin Bishop wrote:
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583
info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741
https://forum.vcfed.org/index.php?threads/dec-ttl-part-number-equiva
le nts.79306/ is a collection of rumours about what DEC 8881's
DS3862 was a National Semi trapezoidal (ie slew rate limited driver), whether that makes
a DS3881 a National part is a good question (never found it).
DEC documentation on LSI-11 BusDrivers mentions the 8881 as having DEC order code 957,
and describes it as a bus driver. The documentation goes on to say that a 8641 is a 8640
(Bus Rx) integrated with a 8881 (Bus driver); followed by pin out (14p classic TTL NAND
pin out) and parametrics. I shall try to find a link to the pdf; I have pp55-58 on A4.
The DS3881 might be an urban myth, perpetuated typo / error ?
That's my tough too..
Regarding the russian Datasheet the K559IP1 can source 70mA (an other databook shows
80mA here) that's over the spec of an 8881 as far as I know, the
"1972_Signetics_SSI_8400_8800_TTL_DTL.pdf page 2-44" has no value for the max
output sink current..
It seems that this part is modified from the russians but listet as
DEC Standard and used for the same purpose as the 8881, but it has a
modified Pinout too (2 extra free pins, DIP16 instead of DIP14)
If found a interesting discussion about the western parts here:
https://forum.vcfed.org/index.php?threads/dec-ttl-part-number-equivale
nts.79306/
I'm a former East-german from "behind the iron curtain"..that's why
I'm at least kew of the existence of that equivalent parts. I still know of a source
of 8640, 8641 equivalents and I've bought the last 7 8T24 equivalents there. This
source is now drying out too...
Regards,
Holm
Martin
PS off looking for URLs
-----Original Message-----
From: Holm Tiffe via cctalk [mailto:cctalk@classiccmp.org]
Sent: 31 July 2025 20:01
To: cctalk(a)classiccmp.org
Cc: Holm Tiffe <holm(a)freibergnet.de>
Subject: [cctalk] Q about DS3881, N8881 DEC8881..
The russians build PDP11's and VAXes. They made chips similar to the special DEC
chips. For example there is an K559IP2 which is an DS8640, and there is an K559IP1 and
they list an DS3881 as equivalent, 4 NAND gates "standard DEC" Bus driver
..hmm.
1,2-3, 4,5-6 10,11-9 and 13,14-12. ..input,input-output. 16 VCC, 8
GND,
7,15 free. It is an 16 pin 300mil DIP.
Now I have problems to find a Datasheet for an DS3881 which is NOT an CCFL Inverter from
Maxim/Dallas/Analog but I' pretty shure I've seen such beasts already in the
past.
An DEC8881 is sitting next to an DS8640 on a DLV11 I have in my hands..but this is an
DIP14 Chip (similar to an 7401 or an 7439).
What the heck could a DS3881 be?
(DEC Bus drivers are getting rare those days, that's the cause that I've bought
those russian chips in the past for cheap..
Regards,
Holm
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583
info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583
info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741