rosen@cs.utexas.edu (Eric Carl Rosen) (03/14/91)
[Yuram N. Yifrah] writes: >Could someone plase help me with a question. What is involved in replacing >the HMMU with the 68551 PMMU in a plain Mac II? And can it be reversed. As far as I know, you merely need to locate the appropriate chip (NOT the one marked 68020 and NOT the one marked 68881 :) ), remove it carefully (a flat blade screwdriver might be helpful here if you don't have a chip extractor kit), and replace it with the 68551. Make sure to insert it in the proper orientation, but I believe the pins will only line up one way. In any event, no soldering is involved. As far as I know, this is all you need to do. I did this and System 6.0.5 recognizes the chip. Of course, I won't be responsible if you follow the above directions and destroy your machine, or even if the directions above are incorrect. However, from personal experience, I honestly believe this is all you need to do. --Eric
dwade@jarthur.Claremont.EDU (Doug Wade) (03/14/91)
In article <1180@yoakum.cs.utexas.edu> rosen@cs.utexas.edu (Eric Carl Rosen) writes: %[Yuram N. Yifrah] writes: %>Could someone plase help me with a question. What is involved in replacing %>the HMMU with the 68551 PMMU in a plain Mac II? And can it be reversed. % %As far as I know, you merely need to locate the appropriate chip (NOT the %one marked 68020 and NOT the one marked 68881 :) ), remove it carefully (a %flat blade screwdriver might be helpful here if you don't have a chip extractor %kit), and replace it with the 68551. Make sure to insert it in the proper %orientation, but I believe the pins will only line up one way. In any event, %no soldering is involved. As far as I know, this is all you need to do. I did %this and System 6.0.5 recognizes the chip. A couple of important points: *It turns out that the metal covers on the back of a Mac II (where your cables from your slots go) work really well for this purpose. *The way you get the orientation right is to look for the dot in one corner. *If you're really paranoid, ask somebody for a copy of the instructions that come with Virtual -- they're really good. *If you don't feel comfortable, don't do it. The cost of having somebody install the chip properly is MUCH less than that of getting a new motherboard. If there's some kind of hourly minimum make them fill out the time generally cleaning out and diagnosing your computer. Many dealers will not have much problem with this. 'luck
Jim.Spencer@p510.f22.n282.z1.edgar.mn.org (Jim Spencer) (03/15/91)
Yuram N. Yifrah writes in a message to All YNY> Could someone plase help me with a question. What is involved YNY> in replacing the HMMU with the 68551 PMMU in a plain Mac II? YNY> And can it be reversed. All that is involved is very carefully unplugging the old unit and plugging in the PMMU. Reversing is the same thing. The only difficulty is in taking your time as there are a lot of little pins that can get bent or broken.