Only one comment about the SE/30, IIsi and IIfx PDS slots. Given enough signal compatibility between the three (from what has been said in this thread toda I assume that the difference is perhaps half a dozen unimportant lines), it may seem feasible to make a board that worked in all three corretly, right? But I don't think so.
We have talked about signals, their distribution in the PDS slot, and their load limits. These are important parameters. But we're leaving alone one very important factor: the bus speed. The SE/30 and IIsi work at "near" speeds (16 Mhz and 20 Mhz), and thus it is possible to desing a card in a way that it work in both of them (it must be a careful design taking into account all components' timmings and time tolerances). But the IIfx works at twice that speed. I think that's the main reason of the "incompatibility" of the IIfx PDS and the IIsi/SE30 PDS. The differences of the IIci slot are even greater: as it is a "cache slot", it may have some raw lines from the processor that the PDS has "cooked" in the mobo's chipset. And also there is that speed difference, from the 16 Mhz SE/30 to the 25 Mhz IIci, much greather than the difference between the SE/30 and the IIsi. Both problems nay be addressed by placing an ASIC in the adapter (and thus isolating the PDS card from the IIci cache slot), but IMHO I don't think it would be a simple gate array that can be reverse-engineered with just a battery and a light bulb :-( . Of course, some of the ideas in this last paragraph are suppositions. They may be right... or not. Please point me where I'm wrong. Greetings, Antonio Rodr�guez (Grijan) <ftp://grijan.cjb.net:21000/> -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
