Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!mit-eddie!husc6!purdue!decwrl!frambo.dec.com!schabacker From: schabacker@frambo.dec.com (CB, posted by generous Tim) Newsgroups: comp.sys.amiga Subject: Re: 2090 Problems Message-ID: <8806271729.AA09868@decwrl.dec.com> Date: 27 Jun 88 17:29:15 GMT Organization: Digital Equipment Corporation Lines: 54 > [Various people complaining about problems with hard disk access > while having overscan/hires (deeper than 3 bitplanes) screens in > front] Well, as mentioned in my introducing message, I have a 2090 with a 70MB Micropolis and a 20MB Epson hard disk connected to it. And as you people might know, we have the PAL video norm over here, giving you a MINIMAL vertical overscan of 56/128 lines compared to NTSC. I experienced the problems descriped, too. First let me say that this problem is only present when working with 4 bitplane (or deeper) med-res/hi-res (min. 640 pixels wide) screen in front, which has some or sometimes NO overscan, due to Chip-DMA (Agnus, that ole lady) colliding with the DMA from the 2090. Well, it's really the hddisk.device in ChipMem not getting enough CPU cycles to do it's job, but read on. Here is what I did to get rid of it: 1. First make sure that your hddisk.device doesn't get into ChipMem or pseudo ChipMem ($C00000-$C80000) on A500/B2000's. So place a "fastmemfirst" or "slowmemlast" BEFORE the "binddrivers" in your Startup-Sequence. (This was mentioned some time ago by Andy Finkel) 2. Then you might do some trick that I found to work most of the time, even BEFORE I did #1. Change your preferences, so that your Workbench starts at the leftmost position. This seems to help by some magic to relieve some of DMA strain. Don't ask me why (Jay?). This works only with programs that "clone" the Workbench screen like ProfPage, SuperBase Professional, Shakespeare, etc. The 2090 is the fastest Amiga HD controller I've seen so far, really nice design, no comparison to C-Ltd. I have a long list of diskperfs available, if inquiring minds wanna know. :-) My Micropolis tops ie. at 238312 bytes/sec read and 174762 bytes/sec write (FFS 34.76 on gamma7) . And that's an ST-506 drive!!! - P.S. Could someone please e-mail me the newest version of hddisk(.device)? Mine is Version 33 (rev 37) (Mon Oct 26 11:06:14 PST 1987), a little bit out of date, no? -- __ __ / / | \ \ aka Christian Balzer - The Software Brewery - // / / | \ \ UUCP : decwrl!{frambo|fra03|fra04}.dec.com!schabacker // < < |---< > or : schabacker@{frambo|fra03|fra04}.dec.com \\ // \ \ | / / CIS : 71001,210 (Be brief!) | Phone: +49 6150 4151 \X/ \ \__ |__/ / Snail: Im Wingertsberg 45, D-6108 Weiterstadt, F.R.G "If there is something more important than my ego, I want it rounded up and executed." If you think this .signature should shrink your're right!