Monday, March 25, 2024

How the Entrex 480 / Nixdorf 620 Boots

March 24, 2024 From Bruce Ray with Wild Hare Computer Systems /

The standard DG/DCC Data Channel device [DCH] tape/disk bootstrap program consists of only 3 instructions:

375/ 062677   IORST

376/ 0601<xx> NIOS <device code>

377/ 000377   JMP 

This is the program initiated by the PL switch on the 'standard' machines

DCH device controllers are designed to boot from record/sector zero of a tape/disk drive into location 0 onward, and therefore overwrites the JMP . instruction at location 377.  Any standard bootable DG/DCC tape/disk [and I would assume Entrex] successfully uses this model.  If a faithful image of a tape/disk is created and appropriately configured in an emulator, the system should be 'bootable'.  A correct SimH-compatible tape restoration works on all of the very-diverse systems I work with, and likewise for disk images and appropriate disk emulation configuration.

Therefore, if a known "bootable" tape is accurately recovered to SimH-compatible format, the resulting contents should behave exactly like the original hardware if the various parameters are met.    This is the basic approach successfully used over the decades for handling even the 'weirdest' client situation.

Once the controller is started [i.e. NIOS <device>] the controller will transfer words from the device to main memory automatically.  Even if an extreme custom hardware modification were made to the front console's program load logic, the examination of the tape/disk record/sector zero might reveal more information, faster, than trying to grok custom hardware modifications.  Knowing the exact [human] operator procedure to bootstrap the system would reinforce

the decision to attack the problem either bottom-down or bottom-up.  Top-down In this case would be to start with a known good accurate copy of the tape/disk media in question, bottom-up would be dissecting schematics to discern the forest from the trees... 


We provided Bruce with these two recovered SimH-format 9-track tape files:



to which Bruce replied with these glorious preliminary results:

Tuesday, March 12, 2024

Pertec 9-track Formatter "Key To Tape" device

This device is NOT part of the Entrex 480 system, 
but in order to understand a "Key-To-Disk" system like the Entrex 480, 
here is a "Key-To-Tape" stand-alone device to illustrate the differences.  

Saturday, March 9, 2024

IBM 029 Keypunch Keyboard vs Entrex Data/Scope

Compare this keyboard to the "029" keyboard option for the Entrex Data/Scopes (Keystations).  As the Entrex 480 advertisements state, this keyboard layout was a featured option on the Entrex Keystations so that operators who were used to the IBM 029 keypunch keyboard layout were able to transition to using the Entrex Data/Scope without any re-training on the keyboard layout.  How cool was that?!

Saturday, November 11, 2023

Alan Warren's "in-desk" Entrex Data/Scope with DEC VT-05 and PDP-11 home setup

posted by Alan Warren

It should be noted that the PDP-11 is mounted into an Entrex 480/Nixdorf 620 Rack Chassis, so this is a "PDP Retrofit" into an Entrex 480 system chassis!

Too bad that all of this was scrapped many decades ago...but we thank Alan for the vintage picture!!!

Saturday, September 30, 2023

A Forgotten Machines T-shirt visits the MHKI and the Mera 7951 in Katowice

These pics were taken by my friend Kris on his visit today to the Muzeum Historii Komputerów i Informatyki (Museum of the History of Computers and Information Technology) in Katowice, Poland.

What an honor it was to see him there, wearing our branded T-shirt!  I cannot wait for the time to come for me to visit this wonderful place myself!

Monday, September 4, 2023

Entrex (Nixdorf) Trapezoid Data/Terminal spotted in The Love Boat Season 1 Episode 20 (1978)

Thanks to SomePeopleCallMeJJ for finding this!

You can actually see the Nixdorf badge pasted right over where the Entrex logo silkscreen would have been in the lower left of the plexiglass on the screen

Notice The Love Boat model has the 029 keypunch-style keyboard

Next, find the original 3:4 aspect ratio format and show HQ screen shots
Identify the foreign device under the computer, which may be a real (or fake) punch card reader.  Is this also a Nixdorf product?  Could be...
Perhaps there was some Nixdorf sponsorship going on in this episode??

Monday, April 17, 2023

Cortron 35-500179 80-350253 Keyboard for the Entrex Trapezoid Terminal

Notice that the build date on the ID tag of this keyboard says 1986, even though that is a full 7-8 years after the build of the rest of the terminal (1978-79).  The IC chip dates all seem to back this up on the keyboard (84-85 dates) and the terminal (78-79 dates) This is curious, but not unheard of.
Since only 5 of these terminals are documented to survive in the world so far, what are the dates of the other 4 keyboards?  We shall find out...because we have 3 of them, and we hope to get dates from the other two!