Nr.fabr. 6952 - Rok 1987 (MINE)
Sunday, January 8, 2023
Saturday, January 7, 2023
Monday, December 26, 2022
Saturday, December 3, 2022
Friday, November 4, 2022
Friday, September 30, 2022
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
How does the Entrex/Nixdorf "Trapezoid" Data/Terminal work?
Well, we don't know yet...but we're working on it. For starters, here's some context to see how it was advertised:
Sunday, September 4, 2022
Motorola CRT Chassis H 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)
and
Also, similar on the system board:
Friday, September 2, 2022
Polish Advertisement Claim "Entrex is compatible with the Mera 9150"
Thank you, @sergiopl for providing this treasure!
Full translation to English coming soon...
Monday, August 29, 2022
Technical Manual for the Data General Nova 800 - OCR'd
These manuals are on bitsavers here:
But alas, they are not OCR'd (optically character recognized) PDFs.
So, with some magic using ocrmypdf, I'm making OCR'd versions available here. Enjoy!
Then here's a couple extra tangential links for fun:
Friday, August 26, 2022
Entrex Data/Scopes (Nixdorf Keystations) spotted in Belgium on 2ememain.be
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!
"The ad was on https://www.2ememain.be
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
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
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:
MBZ = + TERMINAL BUSY
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.
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