Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!mit-eddie!dorian From: dorian@eddie.MIT.EDU (Dorian Garson) Newsgroups: comp.sys.atari.st Subject: RE: Turbocharging the ST Message-ID: <7585@eddie.MIT.EDU> Date: Sat, 5-Dec-87 10:21:34 EST Article-I.D.: eddie.7585 Posted: Sat Dec 5 10:21:34 1987 Date-Received: Thu, 10-Dec-87 05:50:14 EST Reply-To: dorian@eddie.MIT.EDU (Dorian Garson) Organization: MIT, EE/CS Computer Facilities, Cambridge, MA Lines: 77 I received the following message in response to my request for info about installing a 68010 or -020 in my ST: +----------------------------------------------------------------------+ Hi, I did the software part of the replacement of the 68000 with an 68020 in an ST, and maybe this is a good moment to report our results. Note that although I have obtained a degree in EE long ago, I'm not a hardware guru. This was a two person project (Henk did the hardware stuff, I did the software). Forget about using the 68010. It brings a lot of trouble without any significant speed change (expect a few percents due to the loop mode). We therefore went straigt to the 68020. We decided to use the PAK-68 card, as described in c't, august 1987 (a German magazine). This card replaces the 68000 with an 68020 and optionally an 68881. The 68020 works with a 16 bit data bus. Also additional logic is provided for synchronous bus cycles. As already stated by c't, and confirmed by Atari Benelux, this board does not work with TOS. Probable cause: timing loops and weird code (example: build your own stack frame and do an RTE). The whole thing works with RTOS (a real time os from Germany, not related to TOS). Since RTOS is not that cheap, we decided to do some own experiments first. The following was done: >From Johan Stevenson, I obtained a beta release of MINIX (thanks Johan). I made a new bootstrap routine. It worked. (Ok, it was not that easy, its hard to debug bootstrap routines) The results were a litte discouraging though. We only tested with the dhrystone benchmark, as posted on the net before. Minix/68000 did around 714 dhrystones/second. This is almost equivalent with the DRI compiler from TOS, but since both minix and the benchmark program on minix are compiled with this compiler, this is not surprising. The results on the 68020 were: cache enabled: about 769 dhrystones/second cache disabled: about 515 dhrystones/second. There is no explanation why the latter result is so much worse than the 68000 results. The difference with cache enabled and disabled is about what was expected. And this is where the story ends... Henk sold his system, and I did not feel capable enough to find the cause of this delay. I don't feel that the gain obtained now is worth the investment in this card. Any other experiences/results?? By the way: the response from Atari Benelux has always been one of laughing: what you're trying to do is impossible. Well, it can be done. Not with TOS, but only with real operating systems (which use interrupts for I/O instead of timing loops). Anyway: does anyone know exactly what to do when writing your own loader for TOS. I know the story in the hitch hikers guide, but would appreciate some additional info. Anyone? Oh yeah; about that PAK card. In the november issue of c't they describe a small card to switch between 68020 and 68000. For those who want to go to the 68020 but don't want to give up TOS completely (to play PSION?) Please reply to the address below, and not to the address in the header, since this is a shared account. Thanks in advance. Frans Meulenbroeks Centre for Software Technology ...!mcvax!philmds!prle!cst!meulenbr or ...!uunet!prlb2!cst!meulenbr +-------------------------------------------------------------------+ -Dorian->