TOPIC When I try to install Mac OS 7.6 on my Power Macintosh 8500, the installer says it is an unknown system. What is wrong? DISCUSSION The LED cable connected to your logic board may have a jumper in it that is causing the confusion. Having this particular variety of LED cable in a Power Macintosh 8500 can occur after upgrading a Power Macintosh 8100 or Quadra 800 to a Power Macintosh 8500. Both the Power Macintosh 8100 and Quadra 800 use jumpered LED cables. Therefore, if the Power Macintosh 8500 logic board is installed and the LED cable is not changed, you may experience this problem. Also note that there are two different ROM chip versions, each of which handles the 'jumpered LED cable' situation differently. If the jumpered LED cable is installed on a Power Macintosh 8500 with an f1 ROM, the machine ID is reported as 110, which is incorrect. This can be verified with the Apple System Profiler program. Without the jumpered LED cable, the ID is 69, which is correct. A logic board with the f2 ROM is not affected by the type of LED cable attached to the logic board. The table below summarizes the various combinations of logic board ROMs, LED cables, and the results:
This article was published in the 21 May 1997 "Information Alley". |
| Document Information | |
| Product Area: | Computers |
| Category: | Power Macintosh |
| Sub Category: | Power Macintosh 8500 |
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