Arcom SC88T, Technical Manual

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If the SC88T ‘HANGS’ on a bus access, or a bus timeout occurs, check the
following:
Are the address and data lines enabled (‘HUNG’ state)?
If they are not, the SC88T has not gained access to the bus. This may be
because some other master already has access to the bus and has not
released it. Check the state of the BUSRQ* and BUSAK* lines, and jumpers
LK2C and D.
If they are, check that DATACK* or TFRERR* has been received.
If DATACK* or TFRERR* have not been received (Bus timeout)
Check that the slave board can respond to the bus access which the SC88T
sent out.
If it can, check the SYSCLK is present on the bus, as many slave boards
require this for timing, and check also that SYSCLK is coming from only
one source, if you have more than one CPU on the bus.
Check also that your software has allowed bus timeouts to occur, and that it can
deal with interrupts from bus timeouts if they happen. It may sometimes be
useful to disable bus timeouts and check the bus in the ‘HUNG’ state if you are
confused.
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J90 SC88T 2192-08819-000-000