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Thread: ANY documentation about the "Siemens Textsystem 5823"

  1. Default ANY documentation about the "Siemens Textsystem 5823"

    Hello together,

    I take part in restoring an old "Siemens Textsystem 5823", basically a typewriter on steroids. Using a proprietary 8080 computer, a "terminal like" screen/keyboard combination and a daisy wheel printer.
    Does anyone have any (really, every bit helps, we have pretty much nothing) documentation about it?


  2. #2
    Join Date
    Aug 2009
    Oslo, Norway
    Blog Entries


    Do you have any pictures of it?
    That would help in case it is the same as another system (possibly from a different manufacturer).
    Does it look like this picture

    some more links I found
    perhaps contacting that museum helps, perhaps they have more info.

  3. Default

    Quote Originally Posted by tingo View Post
    Do you have any pictures of it?
    That would help in case it is the same as another system (possibly from a different manufacturer).
    Does it look like this picture
    Well, excellent detective work! That's literally the system I'm talking about. I volunteer at this collection .

    IMG_20190711_193140848 (1).jpg

    We already contacted Siemens, they said they may have something in their archives but they are in the process of reorganizing them and aren't able to look it up right now therefore.
    At this point in time, we don't even know if it's complete or has been gutted already. Those just 2 cards in the rack look suspicious.

    Quote Originally Posted by tingo View Post
    some more links I found
    perhaps contacting that museum helps, perhaps they have more info.
    That's worth a shot, I contacted them already.

    Last edited by cerker; July 14th, 2019 at 02:04 AM. Reason: fixed typo, added additional info.

  4. Default

    I took the good camera with my and took a few pictures of the internals, maybe they are familiar to someone (they have part numbers, too) and were used in other systems too, where there IS documentation.

    The electronics tray:

    The backplane:

    Some detail, looks like "Power Good" signals:

    The main system board, containing the 8080 CPU, a 512x8 PROM and 2K of SRAM .. and lots of TTL:

    The RAM board (whooping 64K!):

    The floppy controller (not a single LSI chip .. and there is one for each drive):

    And one of the PSUs, looks like the +5V one:

    Maybe someone knows .. something?


  5. Default

    We got a little courageous and fired it up piece by piece after some inspection.
    So at we first checked the mains transformer, then the DC supplies and so on.

    So far, the CPU does *something*, I get a pattern of status lights which does match the „DISK ERROR“ bit pattern I found in the disassembly of the boot rom. One of the disk drives let out some magic smoke, but that was just a blown tantalum.

    The other one didn’t try to read the disk, but then I saw that the disk rotation speed is WAY to slow and started to notice the smell of warm metal. The phase-shift capacitor of the spindle motor is bad and therefore it turns too slow and gets really hot.
    Replacements are ordered, but besides of that things are looking good so far.

    The big question is if our system disk is still readable...

  6. Default

    There was some progress, I changed the infamous "Roederstein" electrolytics in the power supply of the screen/keyboard unit and powered it up. Nothing exploded an I get a screen typical for an uninitialized VRAM (changes every time I power it up):


    Interestingly, now the system also actually tries to boot from disk! We "wasted" some time diagnosing the drives and so on, but it seems that it checked if essential system components are "there" before attempting anything.

    It errors out with the 4 LEDs belonging to the disk drives all lit, which, according to the disassembled boot code, should be something like "General loading error". Next thing we will try is a patched BOOTROM, which actually shows what went wrong. Not quite sure how to do that yet, I think I will use those other 14 LEDs.

    But if the system disk is bad, that would be bad news .. now replacement in sight so far.

  7. Default

    I was somewhat in a hurry while writing last post, so some additions:

    The system doesn't have a "real" power switch. It uses a small standby power supply, which contains some discrete TTL logic. Switching the system on sends a pulse to this PSU, which actuates a relay. That relay switches the main transformer of the system unit and all the peripherals. Switching off, on the other hand, just fires an interrupt at the CPU, which then does an ordered shutdown and only after that commands the Standby-PSU to power off the system.

    What's interesting is:
    Even if loading the system floppy apparently fails, after trying it at least once the shutdown procedure described above starts to work. Without that, you have to pull the plug. So it seems that it actually manages to load a decent chunk of its software before erroring out.

    The error we see may have 3 (very) different reasons:
    - Sector not found
    - Wrong data record type
    - All sectors on track 0 sucessfully read, but no "end" marker encountered.

    That's why I want to add some functionality to the boot code, which just reports: Which error while reading which sector, and maybe a "ignore that and continue load" function.

    Also interesting, the connection of peripherals:
    They use 25pin Sub-D cables, but those carry a reduced 8080 system bus, just for IO. Every peripheral has some dip switches to set its base adress, e.G. 0x10 for the screen/keyboard, 0x30 for the first floppy, 0x40 for the second floppy.

    I still have some hope that the system floppy isn't completely bad or that it is a memory error or something.

  8. #8


    We did manage to find the whole set of user manuals by now, so we won't need those anymore.

    We are still looking for a system disk, an image or even source code of it, and hardware documentation, even when I have started to trace out the schematics, this is extremely tedious.




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