Friday, September 9, 2022

Paul Cicchetti Entrex Records/History

So, that Frenchtown, NJ auction, from which I acquired our first Entrex 480 system chassis & [some] system boards....Who paid to store these since [what turns out to be] 1981?  His name was Paul Cicchetti.

There's a lot to say about Paul, as we learned from the items we acquired from his storage units auction, but this one thing is the most relevant.

Tuesday, September 6, 2022

Sunday, September 4, 2022

Motorola CRT Chassis Connectors - MATE-N-LOK 1-0480270-0

The power & Composite Video combination connector on the top of the Motorola CRT Chassis for the Entrex Data/Scope Keystation Terminals (Nixdorf 620 & 600-series)

Friday, August 26, 2022

Entrex Data/Scopes (Nixdorf Keystations) spotted in Belgium on

My friend Dominique just shared these with me.  The story is:

"I also saw an ad for two Entrex terminals two month ago, 40km from my house [in Liedekerke], Unfortunately the person never answered me, It was strange because one of the two terminals was painted red (like in Knight Rider), I kept the pictures for you."
So, can we track down this seller, or these terminals?  We will certainly try, indeed!

It's a Belgian marketplace, but unfortunately the ad disappeared. I then found the person on facebook by cross-checking information but also no answers. From memory it was in the Antwerp region, in this situation, I can not tell you more alas. It was strange to see this ad anyway, like as a sign, because in fact I have never seen an Entrex terminals ad so close to my house"

At first, I thought that these *might* be the same two keystation/terminals sold in Germany back in March & April 2018, but a quick comparison of any of the tags on the inside shows that they are all completely different machines...  

Friday, August 5, 2022

Entrex 480/Nixdorf 620 Data/Scope Keystation (Terminal) Communication Protocol

sergiopl — Sept 3, 2022 at 3:56 AM
On a PC keyboard there is a tiny CPU that creates scan codes for each key, even shift. Then there is a 8051 or something known as keyboard controller that interpret that and send to PC CPU

In Mera/Entrex you only get scan codes generated from EPROM, mixed together with bit flags connected to modifier keys and that is shifted out of the device
All "meaning" of the keys is up to the host

ashlin4010 — Sept 3, 2022 at 4:03 AM
so how many bits are used for the code and flags? 8 and 2?

sergiopl — Sept 3, 2022 at 4:04 AM
6 bits are keyboard code
3 bits for control character (modifiers)
1 bit to indicate if key is a response to key press or to "read screen character" command
Rest is padding / framing
Those 3 bits are also messed up - they don't cover all possible combinations and some modifier combo has the same bit pattern 😆
If you open polish manual linked above there are two tables with those modifiers

Terminal Connector Pinout:

Similarities with the MERA-ELZAB 7951 terminal pinout:

sergiopl — Sept 6, 2022 at 5:11 PM
I think Entrex code also can be said slightly modified Manchester, but I'm not sure if that is really the case. It looks like except clock signal is not interleaved on each half of bit so this is a bit strange
This is also not a NRZ or NRZI code, also similar but not exact.
But in terms of non repeating sequences it matches definition of Manchester

sergiopl — Sept 6, 2022 at 5:13 PM

There you have it: 3270 controller board
Building an IBM 3270 terminal controller_Lobsters - MdEditor
Building an IBM 3270 terminal controller
This is Manchester encoding. As you can see "1" is sent as LoHi. "0" is HiLo
In our case "0" is LL if previous bit was "1", and HL if previous bit was also 0.
"1" is HH if previous bit was 0, LH if previous bit was 1
While it looks similar over the wire sampling point is different and encoding method is also different
But this approach simplifies decoding because you just need to sample at 3/4T and you are done.

Saturday, July 9, 2022

Nixdorf (Entrex) "Trapezoid" 06418 Terminal saved in Austin, Tx!

This and other vintage machines were acquired by "SomeComputerGuy", from another guy clearing out a storage unit. 

"He does salvage and this is some stuff he had set aside.  I asked him repeatedly if he knew anything about where any of it came from, he did not."

We celebrate SomeComputerGuy's find, and are collaborating to reverse-engineer the terminal communication protocols!  Thanks for sharing the experience with us!

Thursday, April 21, 2022

Entrex has been added to Bitsavers!

Many thanks to Al Kossow and team for scanning and making available their full collection of Entrex publications.  Very rare and unknown, mostly, until now!

Here's the collection:

Also Nixdorf has had a collection there since May 2019.

Of particular interest to us here:


Also, this John W. Rollins, Jr. oral history artifact references Entrex.  

It contains a REALLY interesting real-life case use of the Entrex System!

Wednesday, April 13, 2022

Nixdorf 620 System in Bremen, Germany - Acquired & Saved!

We were thrilled to acquire this and take delivery!  Now we just need to find a way to get it from it's holding place in The Netherlands to the central USA...we're working on that, and we have great friends in Europe to help! 

Tuesday, April 12, 2022

Conversation with former Entrex technician Bob Rooney

Thu, Apr 7, 2022 at 1:22 PM <robert rooney> wrote:


Sorry it’s taken so long for me to respond.  Just came across your site again.  It sure brings back a lot of good memories!!!

I started at Entrex in Burlington Mass in the summer of 1974 (summer job between jr and sr years of high school.  I then went back to work for them in May 1975 and stayed until June 2000!!

Yup, Entrex to Nixdorf to Siemens Nixdorf and Siemens.  They whole time working on the 280, 480, 600, 655 systems.  Each a successor to the prior system. 


Summer 1974 assembling data scopes and recently introduced data terminals

May 1975 back to work in the wave solder room - a single person hell hole!  If you can imagine, hot greasy, messy, etc.

That didn’t last long when a friend from the board test department started to show me TTL logic diagrams and I soon started troubleshooting circuits boards for many of the boards in the system and terminals down to the component level.

1977 Promoted to group leader of the data terminal assembly line – they wanted a tech to man the department because they were having too many failures in the field on new installs.

1979 Moved on to the ‘staging test dept’ where systems were configured with all the components (except the data terminals) the customer ordered and we would run them through tests, and alignments of tape and disk drives, etc.  let them run a few days before moving them to the shipping dock. 

Aside from the mentioned systems I also got to work on the Nixdorf made systems we sold in the US: 8850 8860 8870 8890

1982 Moved the ‘national support group’ where I provided hardware support for the x80 600s and 8850 systems to the US customers.

1984 Moved to the software side of ‘national support group’ Supporting the DPEX operating system and some DIDOS o.s. DIDOS was the German version of DPEX.

1987 As Unix started to make inroads and customers no longer wanted proprietary systems  DPEX  was ported to UNIX as an application called DCPA.  It ran on Siemens-Nixdorf RM risc based servers and also x86 servers – using SCO Unix, Unixware,

I had a big hand in developing the applications to convert the DPEX- based customer libraries (their editor programs) and data; output it all to tape and read it back into the Unix servers.  There were hundreds of customers that needed this done. 

1998 things started to slow down and they were actually letting people work from home at that time through a dial-up connection.  Colleagues were laid off, etc.  I was able to re-locate to my house.

I actually had two 8850s at my house and an array of Siemens PCs.  X86 servers where shipped to my house for staging, installing DCPA, and creating conversion tapes. 

June 2000  worked slowed and they were looking for volunteers for a lay off. 

Oct start at Lucent which became Alcatel-lucent and then Nokia.  Stayed until let go in Jan. 2018.

About 10 years ago I scrapped all the equipment. 

Please feel free to fire away; I’ll try to answer anything I can.

Have a great day,