Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!ut-emx!ccwf.cc.utexas.edu From: daveh@ccwf.cc.utexas.edu (Dave Huang) Newsgroups: comp.sys.apple2 Subject: Re: OctoRAM and DMA Message-ID: <47549@ut-emx.uucp> Date: 20 Apr 91 15:45:23 GMT References: Sender: news@ut-emx.uucp Reply-To: daveh@ccwf.cc.utexas.edu (Dave Huang) Organization: The University of Texas at Austin Lines: 29 In article whitewolf@gnh-starport.cts.com (Tae Song) writes: >|running with my RamFAST with DMA enabled and my TWGS. My understanding is >|that no matter how many slots for ram your card has, the Apple IIGS will only >|do DMA to the first 4 rows (SIMMs) for a maximum of 4 meg. If you use 256k >|parts in the Octoram, that means that only the 1st Meg would be DMA (not good) >|If you use 1MB parts, only the 1st 4MB would be DMA. The apple IIGS CANNOT >|do DMA above 4MB of ram no matter what ram card you have. Having more than >|4MB in your Octoram should work fine, just realize that properly built >|hardware will not even try to do DMA to any memory above 4MB. I thought that if the card does its own address mapping, it's possible to DMA over 4 rows. Isn't the GSRAM+ DMA compat up to 6MB? >Oh no. DMA is limited to the first 4MB, not 4 first row. It doesn't matter if >you use 256K or 1, 2 or 4MB SIMMs. It's just 4MB. Nah, DMA is normally limited to the first 4 rows in a GS... No RAMcard currently available for the GS takes 2 or 4MB SIMMs. >INET: whitewolf@gnh-starport.cts.com >UUCP: crash!gnh-starport!whitewolf >ARPA: crash!gnh-starport!whitewolf@nosc.mil -- David Huang | Internet: daveh@ccwf.cc.utexas.edu | "How much is that hamster UUCP: ..!ut-emx!ccwf.cc.utexas.edu!daveh | in the window?" America Online: DrWho29 |