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Another IIci ROM hack

Posted by: tt on 2011-10-16 21:51:57 IIsi ROM SIMM: 1 to 13 connected 1 to 46 connected 1 to 63 not connected

Posted by: dougg3 on 2011-10-16 21:58:21 Thanks! I'm assuming this is the SIMM you're referring to? I guess what's confusing to me is I don't understand why on your pics of the SIMM, pin 1 is routed separately as a thin trace. I also don't see anywhere in the X-ray where it gets connected to the +5V layer, so that's odd. Maybe it's connected internally in the chips? Oh, and your test of pin 46 is showing that Apple's IIsi dev note is wrong, and my unmodified SIMM should work in a IIsi.

Posted by: tt on 2011-10-16 22:12:15 Oh, yes, the ROM SIMM, the same one that was x-rayed. That trace looks like it goes to a bunch of vias, and some of them are obscured, so I'm not sure how it gets connected. Maybe under the third chip from the left?

Posted by: dougg3 on 2011-10-16 22:28:23 Ooh, I see what you're talking about, but the vias underneath that chip go to address lines on the SIMM contacts, so they probably don't connect to that line. I'm guessing that +5V is connected internally to that pin on the chip. Also since Apple didn't hook up pin 63, I probably won't either. I'm thinking I'll use pins 1 and 46 for power and 13 for write enable, and that should do it...

Posted by: dougg3 on 2011-10-17 21:53:42 I did the changes I talked about with deciding which pins are +5V, added some pin numbering on the silkscreen, and ordered 10 rev. 2 boards! This time I went for expedited UPS shipping. The shipping costs about the same as the boards, but I really want the new boards here faster 🙂 I've attached the FreePCB layout if anyone wants to play around with it in FreePCB! SIMMVersion2-4.zip

Posted by: Trash80toHP_Mini on 2011-10-17 22:48:04 😎

Posted by: olePigeon on 2011-10-18 10:46:44 I can't wait! :O

Posted by: olePigeon on 2011-10-18 14:52:07 It occurred to me that if you guys end up designing a SIMM programming board that'll work with other models, most notably the 9700 prototype, then that could also be used for the Apple Network Server, correct? From what I understand, you can stick a 9600 ROM in an ANS so you can run Mac OS on it, and not just A/UX, but you lose access to several pieces of hardware (most notably the SCSI controller.) Would be interesting in the future to not only make clean 9700 ROMs available to 9700 owners, but perhaps enable hardware support on the ANS when running Mac OS.

Posted by: Trash80toHP_Mini on 2011-10-18 17:27:40 Page 14 and counting! :approve: By the cards arrive and you troubleshoot them, maybe I'll have the spare $$$$$$ to order one! :🙂

Posted by: dougg3 on 2011-10-18 17:48:05 Making a programmer board compatible with everything would definitely be more difficult. For starters I would have to add a way to connect to the DIMMs that most Power Macs used, and routing that will be weirder, I think. Luckily, though, we wouldn't be constrained by board area and thickness like I am with the SIMM itself. We'll see! Right now I only have plans to make my first programmer board work with the older II-series SIMM. Even if someone else steps up to the plate and designs something awesome, I'm going to make my own for the experience 🙂

Posted by: olePigeon on 2011-10-18 18:13:05 Sign me up for one. 🙂

Posted by: Trash80toHP_Mini on 2011-10-19 19:03:27 I'm wondering if the SE/30 SIMM might boot the IIsi?

Posted by: Trash80toHP_Mini on 2011-10-19 19:47:29 GAAAAAAAAAAAAAAAAAAAAAAAA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! < bangs head repeatedly on surface of 21" CRT face . . . xx( . . . quiets down > I finally found a set of four of the most decrepit, three chip 30 pin SIMMs and quickly installed them in my IIsi . . . . . . and they're still only those *&^*&%^&^%&^$ 1MB sticks! I've been trying, for a couple of weeks now, to locate a set of ye olde keychain SIMMs, you know, those 256k POS SIMMs that NOBODY wanted in their Macs if they could possibly help it and weren't worth the price of their PCBs after about 1990! All this for a simple test of the IIsi w/IIfx ROM SIMM and matching RAM allocated to both freakin' banks that the IIfx ROM seems to wanna' to see to boot! Well, it's off to the Trading Post I go!

Posted by: dougg3 on 2011-10-26 18:56:18 Update time! I just received my tracking number for the PCBs today from Seeed Studio, and lo and behold, they were out for delivery. So with an order placed on Monday, Oct. 17, that was a 9-day turnaround with the UPS shipping. UPS claims it was shipped on October 24th, so it only took 2 days to arrive here (well, except for time zone differences, so I don't know for sure). Anyway, very nice! Seeed must not have been feeling quite as generous, since I only received 10 this time instead of 12, but since I only paid for 10, you won't hear any complaining from me! They arrived on the same day as my hardcopy of the Steve Jobs biography from Amazon. Coincidence, or is it a sign from above??? ;-) Here are the revision 2 PCBs: Looks like they turned out nice! I love olePigeon's jolly roger graphic -- with the LEDs it's going to look AWESOME. I wonder what the PCB manufacturers thought when they saw that? ;-) The vias are, in fact, big enough for the header now: You'll notice the second pin from the left is shorter -- I believe this is from me pulling it in and out several times to test stuff out. The header has to go out from the back side with the graphic and capacitors, because if it goes out the front, the IIci's cache slot is in the way when you try to insert it. If other motherboards have similar clearance issues on the back side, I may have to abandon the programming header idea. But I'm hoping to make it work with 64-pin SIMM sockets anyway. 🙂 I haven't done any electrical testing, so I may do that just to confirm Seeed Studio's testing, and build one soon! Unfortunately I didn't expect the PCBs to arrive so quickly, so the resistors and LEDs are still en route. Still, I should be able to build one and leave the LED circuit out just to test the functionality. And who knows, maybe the extra parts will arrive soon anyway? We'll see when I get around to building one!

Posted by: Trash80toHP_Mini on 2011-10-26 19:35:03 VERY, VERY 😎 !!!!!!!!!!!!!!!!!!!!! I can't wait to test one with just about every 68030 ROM image under the sun! My IIfx ROM SIMM in IIsi saga continues . . . :🙂

Posted by: dougg3 on 2011-10-26 21:48:46 Unfortunately, at least one of the SIMM PCBs is not testing OK -- I'm finding several instances of adjacent pins being electrically connected together. It may have happened after I increased the size of the vias above the SIMM contacts to make room for headers to fit. (This was one of the untested boards--one of the tested boards I also looked at does not have this problem). I'll have to try to physically find the problem, and hopefully it's fixable with an X-acto knife! I couldn't find anything after a quick inspection but I'll look at it more thoroughly tomorrow. This means I'm going to have to test every (un-marked) board before I assemble it.

Posted by: olePigeon on 2011-10-27 09:59:34 [butthead]This is the coolest thing I have ever seen.[/butthead] Oh man, I can't wait. 🙂 So the holes are there for possible future programming via a USB board? [Edit: Nevermind, just read it]

Posted by: olePigeon on 2011-10-27 10:16:23 But I'm hoping to make it work with 64-pin SIMM sockets anyway. 🙂 White with metal clips? Or black with single tension clip? And how many? 😀

Posted by: tt on 2011-10-27 12:12:08 And how many? Cool, I found there's a local shop that also has these, so it looks like there are plenty to go around. Metal clips are probably better.

Posted by: olePigeon on 2011-10-27 12:25:48 Certainly less stress on the board to do the 45° and snap in place than to push down until the white clip locks.

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