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Ic help/ eeprom question — Parallax Forums

Ic help/ eeprom question

ReconRecon Posts: 3
edited 2005-11-07 15:10 in BASIC Stamp
Have some old IC I pulled from 1994 era computer collection dust in garage.· Searched for hours for data sheets for IC : W24M257AK-15.· Windbond.·RAM of some sort???·is my guess.·

I removed a Chip from an old Locknetics Access controller 128k/256k SPI Serial CMOS E2PROM,· Data Sheet specs. very close to the 24LC16B EEPROM used with the basic stamp OEM.· Since the PIN OUT is different I know it will not work by just pluging it in the socket on the OEM board, however Can it be used in place of the 24C.· Experiment #32 in Stamp Works Book I2C communciations.

Mike

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-11-06 03:15
    Mike,

    ·· This is where it's really a good idea to compare datasheets.· Even if the chips are the same size and have the same pins (even pinout) doesn't necessarily make them compatible.· Some things, such as timing and command codes (instructions) can be very different.

    ·· If you're going to salvage old parts there's two things you need to do.· Compare datasheets and experiment a little.· Experimenting is how I first learned to get an LCD to work on a Z80 without all the parts they described in the datasheet.· In other words, to find a way around it I had to simply try things.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • ReconRecon Posts: 3
    edited 2005-11-06 17:53
    Thanks for the quick reply Chris, I was looking over the data sheets last night and seems to me 128k chip should work. There are some command code differences that have to be worked out. When you are adding eeporm in support of the basic stamp are you able to view the (external) EEPORM memory usage I.E. via Mem. map?

    IS EPROM = E2PROM?
    Mike

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    mike@losteagles.org

    www.losteagles.org
  • John R.John R. Posts: 1,376
    edited 2005-11-06 18:15
    Strictly:

    EPROM: Erasable Programmable Read Only Memory (e.g. U/V light to erase)

    E2PROM: Electronicly Erasable Programmable Read Only Memory. (Can be erased via code or electronic signal to a pin(s).

    Depending on what you want to do, they can serve the same function. EPROM can not dynamically be re-written to. The terms are not always strictly applied, depending on the conversation context, and who's talking.

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    John R.

    8 + 8 = 10
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-11-06 21:16
    Recon,

    ·· No you can't view the EEPROM from the Stamp Editor's memory map as it's not a part of the BASIC Stamp's program memory, nor can you expand that.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-11-07 15:10
    Chris is right -- the Memory Map does NOT view the eeprom contents from the BS2. Instead, it shows you what the eeprom contents WOULD BE, should you download the current program in your PC that you just compiled.

    The BS2 normally does not let you see what is in the EEPROM, in order to protect your intellectual property rights. You CAN write a program which will 'dump' the contents of the EEPROM from the BS2 to your computer -- but loading that program into the BS2 WILL erase all the eeprom first, so you can't use that for reverse engineering either.

    And the BS2 run-time only knows how to deal with 2KByte EEPROM memory spaces. The "larger" BS2's (BS2sx, BS2p) use multiple 2K memory 'banks' to get around this -- but you still can't just call a subroutine from one bank to another.
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