Ian Houldridge <ian@PROEM.DEMON.CO.UK> wrote:

>1.  I am using an ICE TECHNOLOGY Micromaster LV programmer, and the
>    parameters .... for the 17C42 says that Vpp is 11v, not 13v as in
>    the '95 data book.
>
>    I have contacted ICE and they have told me that a Vpp of 11v
>    is acceptable using the 'new' algorithm supplied to them by
>    Microchip.
>
>    A number of times now, I have had a chip 'on test' for a few days
>    which is o.k. at first and then fails.  The failure is due to a
>    bit becoming 'unprogrammed'.  Anything to do with the low Vpp

    Undoubtedly.  Let's see... Microchip's programming algorithm states
    13V, their own programmers use 13V, and no one complains of PRO
    MATE-programmed 17C42s losing their memory.  These ICE guys say 11V
    is ok, and then you have problems with memory retention?  Who are
    YOU going to believe?

>2.  First 'shock' with the above programmer was that the
>    configuration fuses are not supported in the hex.  ICE said that
>    in advance information from Microchip has told them not to bother
>    support this feature as they [microchip] don't believe it is the
>    way to go.
>
>    However, the '95 data book "clearly" (in a fuzzy grey box!)
>    say they Microchip see this feature as been on great benefit to
>    the customer.
>
>    What's the verdict, MChip?

    I think Microchip has made their position clear... Storage of
    configuration information is important.  So far, ICE has given you
    the same weak excuse twice in a row...

>3.  I seem to have lost the thread on the 17C42-JW paperweight saga.
>    Does the 17C42-JW Rev C silicon have an OTP code protect fuse?

    More or less... That is, if you code-protect the parts using the
    method shown in the data book, the code protection is PERMANENT.

>    I have talked to a guy in the U.K. office of MChip .... he said he
>    would find out why it was a good idea and let me know in a week or
>    so.  Any one got any better answers?

    Sure... Think about the implications of a UV-erasable code-protect
    fuse for a minute, and you'll realize that it might be possible to
    erase the fuse without disturbing (much, at least) the rest of the
    EPROM on the die.

>4.  I've had a lot of problems getting MPSIM to simulate an interrupt
>    .... I'm using a version of MPSIM I downloaded in June this year,
>    anyone else have this problem, or is it too many later nights?

    May be too many late nights, but you also might want to download
    the newest version of MPSIM from the Microchip BBS.  Remember,
    17Cxx support is a very new MPSIM feature... It's possible that
    your version has bugs.

    -Andy

--
Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California