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Thread: SUN NVRAM alternate battery clock chip

  1. #1
    Join Date
    Jun 2019
    Vancouver WA

    Default SUN NVRAM alternate battery clock chip

    I recently purhcased an Sun Ultra 5 workstaion, and it as expected had a dead NVRAM clock chip. The one in it is a ST M48T59Y-70PC1D, these are no longer available and cost of $50 from other sources (ebay, Sun recycle businesses). There is a hack where you grind down the chip expose the battery terminals and solder a button battery holder for a CF232.

    I do not have a dermal or a good soldering iron, so ordered from digitkey an ST M48T58Y-70PC1


    this cost around $17.

    I installed this in my Ultra 5 reconfigured the NVRAM and it works.

    The M48T58Y is nearly identical to the M48T59Y, One has an extra enable in the place of the RST/IRQ. Seems these are not used. The documentation on both chips in near identical accept for the 2 pin changes.

    to program the NVRAM on the boot prompt I typed in

    you will need to get the machine type

    01 2/1x0
    02 2/50
    11 3/160
    12 3/50
    13 3/2x0
    14 3/110
    17 3/60
    18 3/e
    21 4/2x0
    22 4/1x0
    23 4/3x0
    24 4/4x0
    31 386i
    41 3/4x0
    42 3/80
    51 SPARCstation 1 (4/60)
    52 SPARCstation IPC (4/40)
    53 SPARCstation 1+ (4/65)
    54 SPARCstation SLC (4/20)
    55 SPARCstation 2 (4/75)
    56 SPARCstation ELC
    57 SPARCstation IPX (4/50)
    61 4/e
    71 4/6x0
    72 SPARCstation 10 or SPARCstation 20
    80 SPARCstation Classic, LX, 4, 5, SS1000, Voyager, Ultra 1, Ultra 2, Ultra 60/80, Ultra 5/10/30, Blade 100/150

    next you will need you hostid (this is on the yellow label on the old M48T59Y being replaced, it is a 6 digit hex number).

    so for example if I was going to program an Ultra 2, with host ID DF56A4 I would enter the following
    setenv diag-switch? false

    1 0 mkp
    80 1 mkp (this is the real machine type)
    8 2 mkp
    0 3 mkp
    20 4 mkp
    df 5 mkp
    56 6 mkp
    a4 7 mkp
    0 8 mkp
    0 9 mkp
    0 a mkp
    0 b mkp
    df c mkp
    56 d mkp
    a4 e mkp
    0 f 0 do i idprom@ xor loop f mkp

    After you have typed this it will appear to hang on some systems, it has not enter ^D ^R (control D, control R) to drop down to the command OK prompt.

    To verify the all is well type .idprom

    should print out Mac and host with a checksum of 29

    for more information see (this is where I got this information)

  2. #2


    I just got done doing the exact same thing to my Sparcstation 5 (not ultra) which is a bit older but the DigiKey M48T08-150 worked fine and was about the same price you paid.
    I followed the steps to reprogram and it works perfectly.

  3. #3
    Join Date
    Jun 2019
    Vancouver WA


    Do Not use the ST M48T58Y-70PC, it is not compatible with the SAB SAB82525 controller. This can result in pin 1 or 68 being pulled low and invalidating memory banks. which will lead to watchdog exception or red state exception .

    I did find a US suppler of M48T59Y-70PC1D on ebay for under $9. I will post an update when I get the new NVRAM chip.


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