ychen@watdcsu.UUCP (11/12/87)
I am posting the following article for a friend who is
trying to interface his own expansion card to the
AMIGA 1000 (running kickstart and workbench 1.2).
Bascially, he has problem with auto-configuration and
the AMIGA doesn't seem to recognize the existence of
his card. Here is his article:
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The Schematics and Expansion Specification released by C-A
June 9, 1986 included an Expansion Test Ram Plug-in Card
(PIC) example. The PAL equations for /PRE-CONFIG-OUT and
/CONFIG-OUT were given as well as the schematic diagram.
The schematic diagram, however, clocked U1 (74LS374) with
PRE-CONFIG-OUT*. Since this signal is active low, and U1
is clocked on the rising edge, I think U1 should be clocked
by PRE-CONFIG-OUT.
After making the above modification, the PIC configures
properly and passes CONFIG-OUT* to the next PIC in the
daisy chain. If there are no other PIC's, the system will
continue to boot properly. However, if there is another PIC
in the daisy chain, this next PIC will not be configured.
I found that, as soon as the previous PIC passes
CONFIG-OUT*, the next PIC receives CONFIG-IN* and passes an
immediate CONFIG-OUT*. In my case the next PIC is a
SCSI hard disk interface board.
I suspect that this may be caused if CONFIG-OUT* was passed
while the base address is still on the bus. Thus, the next
PIC would see CONFIG-IN* go low and if the base address was
on the bus, the next PIC would pass an immediate
CONFIG-OUT*.
Has anyone successfully implemented these PAL equations, or
has any other suggestions on what may be causing the
immediate CONFIG-OUT* from the next PIC in the daisy
chain? (I am not including the PAL equations here because
they may be copyrighted by C-A.)
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Thank you very much.
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