Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ucbvax!husc6!endor!stew From: stew@endor.harvard.edu (Stew Rubenstein) Newsgroups: comp.sys.mac Subject: Re: Hypercharger 68020 Board and added RAM. Message-ID: <3529@husc6.harvard.edu> Date: 12 Dec 87 18:49:09 GMT References: <622@bucket.UUCP> <11540084@hpsmtc1.HP.COM> Sender: news@husc6.harvard.edu Reply-To: stew@endor.UUCP (Stew Rubenstein) Organization: Aiken Computation Lab Harvard, Cambridge, MA Lines: 38 In article <11540084@hpsmtc1.HP.COM> kwallich@hpsmtc1.HP.COM (Ken Wallich) writes: >>The Hypercharger user manual says 3.5Meg should be available. >>The Hypercharger technical installation manual says 2.5Meg should be available! > >>Its all because of the 68020 and its need to have 32 bit words. >>Mac II owners run into the same problem. >---------- >Why should I (a MacII owner) have problems because Hypercharger doesn't >let you access all your memory? Mac II owners do have the same problem, only worse - if you buy only two SIMMs and plug them into two of the four empty slots, it won't work. With the HyperCharger, it will work, but because of the way memory is divided between the motherboard and the Hypercharger board, it can't map all of it. You have to buy four 1Mb SIMMs and plug them into the Hypercharger board to get 4 Mb of fast 32 bit memory. Note that you can order the board with no memory so you can populate it yourself without throwing away 1Mb of 256K chips. You still get only four, not five, Mb, cause the ROM is mapped in the second four Mb of address space. In this configuration, it's actually FASTER than a Mac II because there is only one wait state, compared to two for the Mac II. On the other hand, you can't plug a 68851 MMU into a hypercharger. >BTW: >Isn't a SE + a Hypercharger + extra memory about the same price as a >MacII with a color monitor? The SE+H020 is cheaper, particularly if you can get one under the GCC developer discount program. I don't think it's worth it unless you already have the SE, though, cause you're gonna someday want color, and a Mac O/S with decent memory management will require the MMU. Stew Rubenstein Cambridge Scientific Computing, Inc. UUCPnet: seismo!harvard!rubenstein CompuServe: 76525,421 Internet: rubenstein@harvard.harvard.edu MCIMail: CSC