Did the first one cause the second one to be listed within the mysterious forces in the vintage computing universe? We may never know!
Entrex 480 Data/Scope
Seeking To Preserve Entrex 180, 280, 380, 480, 580 & Nixdorf 620 Systems & Data/Scope Keystation Terminals
Friday, March 14, 2025
ANOTHER Entrex Data/Scope (Nixdorf Keystation) for sale in Frankfurt, Germany
Did the first one cause the second one to be listed within the mysterious forces in the vintage computing universe? We may never know!
Friday, March 7, 2025
Monday, February 17, 2025
Entrex Data/Scope (Nixdorf Keystation) for sale in Peine, Germany
Saturday, January 4, 2025
Monday, March 25, 2024
How the Entrex 480 / Nixdorf 620 Boots
Reference decoded tapes verbose files on GitHub Forgotten Machines
March 24, 2024 From Bruce Ray with Wild Hare Computer Systems / NovasAreForever.org:
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...
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We provided Bruce with these two recovered SimH-format 9-track tape files:
Entrex_Nixdorf_620_Save_PRIX_22-01-87.tap
Entrex_Nixdorf_620_Master_Didos_1_genere_08-10-83.tap
Friday, March 22, 2024
Mera 7951 OM Terminal listed on eBay in Buk, Poland
Thursday, March 14, 2024
Nine-Track (9-track) 800bpi NRZI Format decoding
00010011 - 0x13 "TapeMark"
01234567P - real world tracks
765391824 - ANSI track order
OK, 3, 8 & 2, or 2,3 & 8... got it now! Anyway, the main point of my message was to say "Thank YOU" on this, and I know I went a bit overboard.
I really should put these last 2 messages into one of my blog posts. It could help the next less-technical person like myself who dares enter this territory...