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How to read code from P87C750?

Discussion in 'Electrical Engineering' started by Gary Walters, Dec 14, 2012.

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  1. Gary Walters

    Gary Walters Guest

    Obsolete data controller from defunct company uses this Philips ucontroller.
    Units are failing and customer has the option of either throwing out all his
    infrastructure when these units fail and spending $$$$ to replace everything,
    or burning new controller ICs as units fail.


    It looks like the P87C750 comes with a 16-byte encryption table, optionally
    used to encrypt the contents of program memory.

    The only way, it seems, to know if the memory contents has been encrypted is
    to read the contents and see if it contains legible code.

    Is there another means to know if the memory contents have been encrypted?

  2. hamilton

    hamilton Guest

    1K of code space is not much.

    A logic analyzer and a few hours with a working unit and you will have
    replacement code ready to go.

    How many of these units are we talking about ?

    2-3 units a month, 2-3 units a year ??

    As the company is now gone, what other type of products are in that
    market place ?

    In this day and age, building a replacement is easier than fooling with

    My $.02

  3. Gary Walters

    Gary Walters Guest

    ADVANTAGES of the 8051 architecture???!!!

    I hope that's not the sound of The Segue I hear...
  4. Well, it sure beat the heck out of the preceding MCS-48 architecture!
  5. hamilton

    hamilton Guest

    On 12/14/2012 2:18 PM, Gary Walters wrote:

    How can I email you directly ?

  6. The early PICs were about unusable for anything complex (ugly paging
    and no interrupts) and I wasted a bit of time trying. I never used the
    RCA thing. Maybe some of the 4-bit ones- they were pretty starved of

    Best regards,
    Spehro Pefhany
  7. Guest

    The 68000. Too boring. ;-)
  8. hamilton

    hamilton Guest

  9. IIRC, they had a Silicon-on-Saphire version for rad-hard applications.

    Best regards,
    Spehro Pefhany
  10. Guest

    CMOS static cells. Really big CMOS static cells.
  11. Guest

    Part of the spacecraft was spin stabilized, the other not (antennas
    and cameras hate that).


    "The spacecraft was constructed in three segments, which help
    focus on these areas: the atmospheric probe; a non-spinning
    section of the orbiter carrying cameras and other remote sensors;
    and the spinning main section of the orbiter spacecraft which
    includes the fields and particles instruments, designed to sense
    and measure the environment directly as the spacecraft flies
    through it. The spinning section also carries the main
    communications antenna, the propulsion module, flight computers
    and most support systems.
  12. I still have the 1802 processor manual from my old cosmac Elf.

  13. Nico Coesel

    Nico Coesel Guest

    Ahhh. Good memories. I had a book about how to build a COSMICOS
    home-brew computer (a PCB with among other electronics a hex-keypad
    and some 7 segment displays) around a 1802. Never build the thing but
    I read the book several times just to learn about designing stuff
    around microprocessors.
  14. Jasen Betts

    Jasen Betts Guest

    Operand order is a function of the assembler, not the architecture.
    Eg: if I use "gas" I get the order you, and "AT&T" prefer if I use
    "nasm" I get the order intel prefers. endianness OTOH is dictated by
    the hardware.
  15. Guest

    Precisely. ;-)
    Too boring.
    Um, name be one thing (in this universe) that moves from its
    destination to source.
  16. Oppie

    Oppie Guest

    Let me see if my Needhams EMP30 supports this chip. Worth a shot to see if
    the program is secured or not. Some manufacturers set the
    security/encryption bit(s) so you can't read it out while others leave it
    I used something similar from Dallas/Maxim (now discontinued)
  17. Guest

    Nonsense. I bet you think all programming languages were invented by
    Intel, then. The "destination" variable is almost always on the left.
  18. There's no use for encryption when the security bits are not set. If they
    are set, you'd not be able to read the device anyway. So read the device if
    you can, get (or write) an appropriate disassembler and you'll see whether
    or not the code makes sense.

    petrus bitbyter
  19. hamilton

    hamilton Guest

    They possibly put in some copyright text into the original source file.

    If you can read the chip, if its not all 0xFF 0r 0x00, look for any
    ASCII text.

  20. Sure, standard procedure - at least my standardprocedure - for examining
    unknown .HEX files starts making a hex-dump with ASCII translation. ASCII
    strings are often interesting but even if they're not they can be skipped
    while disassembling.

    petrus bitbyter
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