Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!bbn!bbn.com!denbeste
From: denbeste@bbn.com (Steven Den Beste)
Newsgroups: comp.sys.amiga
Subject: Does "DigiView" work with a 68020?
Message-ID: <42329@bbn.COM>
Date: 6 Jul 89 16:28:14 GMT
Sender: news@bbn.COM
Reply-To: denbeste@BBN.COM (Steven Den Beste)
Organization: Bolt Beranek and Newman Inc., Cambridge MA
Lines: 37

I've got some money burning a hole in my pocket and I've found an ad for a
place which sells a 68020 board for $350, ostensibly compatable with all Amigas
(my 1000 was explicitly listed).

And of course, the second thing that popped into my mind (immediately after
"Wow, that would be cool!") was "Will it work with all my existing stuff?

DiviView in particular is a good case in point. While a conversion is going on
the interrupts are shut off. The software is detecting both vertical and
horizontal retraces and then using a software loop to decide where on the scan
line to fire the sample-and-hold prior to software A/D conversion.
(It is also probably relying on another software loop to calibrate the
settling time on the D-to-A before checking the comparator in the
A/D conversion.)

If you didn't follow any of that, don't worry. All it means is that the
software is relying completely on knowing that it is running a 68000 of a known
clock rate. If you change either, then unless the software detects that and
uses a different loop constant (or a different loop) then DigiView will get
hopelessly mixed up and totally fratz the conversion, probably by spreading
the leftmost part of the target across the whole screen. [Oh, and the 68020's
cache should louse things up, too.]

My real question is: Has anyone out there actually tried using a DigiView (3.0
software) with either a 14 MHZ 68000 and/or any 68020?

[Now for a stupid question: Does Arkanoids run impossibly fast with a 68020?
It isn't really important, because we can kick it into "slow" mode, but it
would be nice to know if they are synchronizing to the vertical retrace or just
doing it as fast as they possible can.]

[I feel a little guilty posting this because I'm sure it has come up before,
but not VERY guilty, because it isn't in the monthly "most asked questions"
post that just came by here.]

Steven C. Den Beste,   BBN Communications Corp., Cambridge MA
denbeste@bbn.com(ARPA/CSNET/UUCP)    harvard!bbn.com!denbeste(UUCP)