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Thread: Zenith Z-100 boot ROM image wanted

  1. #1

    Default Zenith Z-100 boot ROM image wanted

    Hi,

    I have a Zenith Z-100 (Z-120 all-in-one), but it has an early boot ROM that doesn't have a memory test, and I am looking for a more recent one.

    When I turn the machine on and wait for the hand prompt, typing V gives 'Version 1.2'. Typing T just gives a beep, I understand later versions have a memory test.

    Looking at photos I think the boot ROM is a 27128 EPROM so should be easy to dump to a file using an EPROM programmer. I don't know if the EPROM is in the memory space in either CP/M (8085) or ZDOS/MSDOS (8088 ) mode.

    I have an EPROM programmer so can help reading ROMs of any UK owners.

    Regards,
    John
    Last edited by 1980s_john; October 18th, 2015 at 07:15 AM.

  2. #2
    Join Date
    Oct 2011
    Location
    University Place, Wa. (Tacoma)
    Posts
    29

    Default

    I know that the early roms had a listing available, they are sometimes findable on ebay. I don't have a copy, and as I am in the middle of getting ready to move (in the process of buying a house) I can't really rip mine apart to try to dump the EPROM. Also, I don't recall what version my rom is anyway - might not be any newer than yours, at least in my main machine. The other two I have, also would need to be pulled apart etc. My EPROM programmer happens to be built into a CPM luggable, as well, so it would be - interesting - to try to get the dump onto a network-enabled machine, LOL.

    Anyway, to answer the question about the memory space, I don't know off the top of my head, but either the User manual or the Technical manual should be able to tell you.
    If you want to email me, my gmail is my username, so you can bug me to dig up my links from my home computer for online copies of the manuals, etc. etc. if you don't already have them.
    Sorry I'm not very helpful atm, but I should be able to at least point you towards several resources for these awesome machines, so long as I remember to when I am at home with time to do it!

    Best of luck,
    Ron

  3. #3
    Join Date
    Nov 2011
    Location
    Vienna, Austria
    Posts
    21

    Default Boot rom content

    Here is the content of my Z100 boot eprom (Intel 27128-3)
    Z100_boot.txt
    (ignore the .txt extension, it's a .bin file)
    Roman

  4. #4

    Default

    Many thanks, I burned the image to a 27128 EPROM and opened up my Z-100 (easier said than done). I removed the existing EPROM, this was a 2764, and inserted the 27128. On re-assembling and powering on, I got no response - blank screen, no disk activity, no beep.

    Is there a jumper for selecting the ROM size please (2764=8kB, 27128=16kB)?
    [EDIT]
    Found this in the technical manual:

    J101 Selects whether +5VDC or address line BA14 is
    applied to pin 27 of the PROM. The position shown has
    + 5VDC connected to pin 27 for an 8K x 8 or 16K x 8
    PROM. Move the jumper to the other position to use a 32K
    x 8 EPROM.
    J102 Same as J101 except for address line BA13 and
    pin 26 of the PROM. The position shown is for using an 8K
    x 8 EPROM. Move the jumper to the other position to use
    a16K x 8 or a 32K = 8 EPROM.

    So I need to move J102 - a bit late this evening to try now, so will do tomorrow.


    I will upload my V1.2 ROM at some point for reference, but it clearly it is not as useful as the newer one.

    Regards,
    John
    Last edited by 1980s_john; November 3rd, 2015 at 01:28 PM. Reason: Found manual for jumpers

  5. #5

    Default

    Quote Originally Posted by ronwoch View Post
    Anyway, to answer the question about the memory space, I don't know off the top of my head, but either the User manual or the Technical manual should be able to tell you.
    Thanks, found this in the Technical Manual:

    Memory Control Latch Port (FC)
    This port controls the configuration of memory, both ROM and
    RAM. It also provides an option for checking RAM parity. The
    options, which affect how the ROM is addressed, are enabled
    by writing to the memory control latch (MEMCTL) port.

    The following chart shows which port bits control the four ROM
    configurations.

    BITS DEFINITION
    3 ,2 00 = Option 0
    10 = Option 2
    01 = Option1
    11 = Option 3

    Option 0, the power-up or master reset configuration,
    makes the code in ROM appear to be in all of memory
    when reads are performed. Writes, however, occur normally.

    Option 1 makes the ROM code appear to be at the top
    of every 64K page of memory.

    Option 2 makes the ROM code appear to be at the top
    of the first megabyte of memory.

    Option 3 disables the ROM.


    Regards,
    John

  6. #6

    Default

    With the jumper J102 changed to a 16Kx8 EPROM (27128 ) my Z-120 now beeps, but there is nothing on the display and no disk activity. I will have to revert back to the V1.2 and check all is OK.

    Maybe the ROM is motherboard and model specific, mine has 64K RAM chips, and the video is monochrome with only one bank populated. What motherboard / model does Roman have please?

    Regards,
    John

  7. #7
    Join Date
    Nov 2011
    Location
    Vienna, Austria
    Posts
    21

    Default

    He has a different one

    Here are the pictures of my Z100 motherboard, video and model number.
    mainboard.jpgvideo.jpgmainboard_back.jpgmodel.jpg
    So you can see the board type, the memory chips, the jumper settings ....

    Regards
    Roman

    (unfortunately i shot the power supply, so it has to be fixed before using the Z100 again)

  8. #8

    Default

    Thanks Roman! Sorry your PSU is faulty, I have fixed mine in the past (see earlier posts).

    Your motherboard is part number 85-2653-1, which is the same as mine. As per:

    http://www.retrotechnology.com/herbs_stuff/z100.html

    this is the 64Kbit memory board (max 192KB), can you confirm what memory chips you have as I can't quite read the part numbers, mine has 64Kbit parts, 9 x TMS4164-Z20NL and 18 x MCM6665AL20.

    I see your video card has 3 rows of RAM populated (RED/GREEN/BLUE), mine only has GREEN populated. I have a monochrome screen built into my Z-120.

    I might try a different 27128 EPROM, not sure what other differences there are.

    Here is a dump of my V1.2 ROM Z100 V1.2 ROM.zip for a 2764 EPROM. I plugged this back in and reset jumper J102, machine booted again.

    Hopefully there are also some more ROMs versions out there.

    Regards,
    John

  9. #9
    Join Date
    Nov 2011
    Location
    Vienna, Austria
    Posts
    21

    Default

    Hi, John !
    The ram chips are all NEC D4164C-2.

    Regards,
    Roman

  10. #10

    Default

    Hello John

    I might have what you are looking for. I have the slim model (no display). I set S101 for manual boot and V reports version 2.5 !!! T takes me into a test menu.
    I didn't know about ROM versions or how to check until reading this post. My video has slight pixelation and I had run the diagnostics program from disk to reveal I have bad video
    ram chips U347 and U353. Those chips are TMS4164-15NL. I currently have some on order. Since I got into the ROM monitor, I ran it's memory diagnostic. It's very slow but
    sure enough after about 10 minutes it reports a bad U353. When I get time, I'll post screen shots of the whole process and hopefully a fix with new chips.

    I don't have an eeprom reader and don't want to pull out the rom. Is there a way to read it into a bin file? I can sure do that thru a series of monitor commands or whatever.

    Larry G

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