Re: Astra 1220S

From: Oliver Rauch (oliver.rauch@Wolfsburg.DE)
Date: Tue Feb 22 2000 - 08:50:20 PST

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    "Cornelius, John" wrote:

    >
    > Adaptec AHA-2940/U2W HD68 is compatible but requires a converter with high
    > byte termination from HD68 - HD25.
    >
    > Can some fill me in. What is high byte termination.
    >

    You scsi controller uses a wide=16 bit wide bus. The scanner uses an 8 bit wide bus.
    Both ends of an scsi chain have to be terminated. The highbyte ends at the 16->8 bit
    (wide->fast) converter so it has to be terminated there.

    The problem is that the maximum cable length of a ultra scsi chain is 150 cm
    (sum of internal + external length). If you exceed this length you will get problems
    and may crash data on a scsi harddisk.

    Take a look at available cables/adapters.
    External devices normally use 50 pin (old=not mini) centronix adapters.
    May be it would be better to get a 50->25 pin connector cable
    and a 68(16bit)->50(8bit) converter with included termination.

    Bye
    Oliver

    --
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