Path: utzoo!mnetor!uunet!littlei!intelisc!omepd!hah
From: hah@mipon3.intel.com (Hans Hansen)
Newsgroups: comp.sys.amiga
Subject: Re: hardware question on DTACK'
Message-ID: <2799@omepd>
Date: 6 Feb 88 02:06:30 GMT
References: <1107@louie.udel.EDU>
Sender: news@omepd
Reply-To: hah@mipon3.UUCP (Hans Hansen)
Organization: Intel Corp., Hillsboro
Lines: 20

In article <1107@louie.udel.EDU> rminnich@udel.EDU (Ron Minnich) writes:
$I am trying to add some memory to an A1000. For several reasons
$the hardware is not asserting DTACK. This brings up a question:
$something else is! Is there a watchdog timer in the custom chips that
$automatically asserts DTACK after x cycles? I guess there would have to
$be, else if you addressed non-existent memory the thing would hang. 
$Can anyone fill me in? The hardware manual is not helpful in this case.
$I am hoping to hear that DTACK is not just asserted always by the hardware 
$as this memory cycles in 675 ns (i.e. slowly) so i really need DTACK
$to work right.

DTACK in the Amiga is controlled by the PALs in the A1000 and by the gate
array in the A500 and A/B2000.  All interfacing must live within the alotted
time.  The reason for this is to allow the copper (Agnus) to run at twice
the bus bandwidth of the 68000.

$-- 
$ron (rminnich@udel.edu)

Hans	hah@inteloa	-or-     hah@inteloa.intel.com