Oddbean new post about login | logout Deep diving into buss error handling by reviewing the previous posts and the Lisa Boot ROM assembly. http://bitsavers.org/pdf/apple/lisa/firmware/Lisa_Boot_ROM_Asm_Listing.TEXT If I understand this correctly, memory $282 should hold the address that caused the bus error. In my case, I get 282 0002 0000 which I think is $020000 (high byte is ignored). Does that mean the problem is occurring at position 128kbytes in the RAM card? Not sure how to map that to a component/components yet. #AppleLisaClone #RetroComputing
@8ff2c4ef You got further than I did with that card. I just pulled my Lisa off the shelf and booted it up to make sure everything is still working (it is), I'll try the Sun card again and see exactly what it is doing.
@8ff2c4ef I get two short beeps and a scrambled display with the SunRem card in slot 1.
@96d079fd Bummer! Same tone (lo)? Is the card fully populated with SIMMs? Is display “static” garbage or is it constantly moving?
@8ff2c4ef They're the same tone - I'm not sure if it's hi or lo without a note to compare to (I would have guessed hi). The card is fully populated; I tried 120ns and 80ns sets (one set was provided, the other I bought after). The garbage is static.
@96d079fd You have a 512K card to try in another slot with the 2MB card? I tried the 1MB setting with four SIMMs and got what you described. Only when I added four more SIMMs (and not adding jumpers for banks 2 and 3) did I get a picture. There’s something weird happening. I have a video in this thread (starts with color bars) that has both lo and hi tones for comparison.
@8ff2c4ef Yep, I have two 512K cards I normally use. I put one of those in slot 2, removed the mem 4 SIMMs and removed the mem 4 jumper and I get hi/lo with code 45 and the startup screen. https://files.mastodon.social/media_attachments/files/111/131/651/925/395/727/original/8ae2101f939f18fc.jpeg
@96d079fd Oh wow this is interesting— a bus error as well! I’m curious if there’s a fault with these boards? Does yours have a white silkscreen ID front lower left “42779GY151-190514” ? I think that is a JLCPCB order code.
@8ff2c4ef It does indeed. And here I thought VintageMicros was going through NOS on there. :)
@96d079fd I have no idea, just that our boards are from the same batch is all I can say at this point. That could mean that our boards have the same issue. More testing to be done! I’m going to try to get access to a working Lisa, hopefully tomorrow.
Using the service menu and the display memory command 01FF00 with a length of 100 shows the contents of memory just fine. As soon as I cross the boundary into 020000 (say, with display memory 01FF80 length 100), the machine abruptly reboots and beeps twice (lo/hi). Is this a RAM card problem or a MMU problem? #AppleLisaClone #RetroComputing
It seems the Lisa thinks it only has 128Kbytes of memory, according to these memory locations ($294-297 maximum physical address and $2A8-2AB total memory). Need to look into the boot rom to see how memory size is determined. #AppleLisaClone #RetroComputing https://files.mastodon.social/media_attachments/files/111/129/014/874/572/250/original/662cb362e94f356f.jpeg
This is curious: @96d079fd also has a SunRem 2MB card that hasn’t worked either. And combined with an Apple 512K card, was also able to produce an error 45. https://mastodon.social/@iconicbits/111131652337404316
@8ff2c4ef @96d079fd I have an original working Sun board - I can take some measurements later. You asked about what my PCB looks like? http://www.compu85.net/stuff/Lisa/PCB%20Photos/MEM_F.pdf I built that board out, but it didn't work. I never dug into why :S
@16340ea3 @96d079fd Thanks! That’s three now that started bare, built up, and don’t work. Is this a known issue with these boards?
@8ff2c4ef @96d079fd I just assumed I'd done something wrong, or used the wrong part someplace 😅
@16340ea3 @96d079fd Same here. The odds of that are getting less it seems. I wonder how many more have this issue?
@16340ea3 @96d079fd Looking at the BOM and the card, I didn't notice that U5,6,7 was S373 and U9,11 was LS373. I got all S373. How critical is that? What did you folks use on your cards?
@8ff2c4ef @16340ea3 I have LS in U9,11 and S in U5,6,7 per the BOM.
@96d079fd @16340ea3 Can you get into Service Mode (CMD-S) and read memory locations? What do you get for $294-297 and $2A8-2AB?
@8ff2c4ef @16340ea3 Does this have what you need? https://files.mastodon.social/media_attachments/files/111/132/765/667/558/270/original/2448139a45aed69c.jpeg
@96d079fd @16340ea3 Looks like your total RAM is also showing as 128KB just like mine. What type of RAM are you using? Can you share a photo of the board?
@8ff2c4ef @16340ea3 Sure, here's a photo of the board with the 80ns NMBS marked RAM, and 120ns Samsung (just two modules of the set shown). https://files.mastodon.social/media_attachments/files/111/132/818/286/582/148/original/5ae59b4bf5075ff2.jpeg https://files.mastodon.social/media_attachments/files/111/132/818/846/445/855/original/6d5bf30e7be1de46.jpeg
@96d079fd @16340ea3 Thanks! I have those NMBS modules as well and so far they are the only thing that’s close to working. I have two other sets (OKI and Fairchild) that don’t seem to work.
@8ff2c4ef @16340ea3 I looked through my notes and NMBS is what VintageMicros provided in the kit. The Samsung modules I picked up later hoping it was a RAM issue.
@96d079fd @16340ea3 Good to know, thanks!
@8ff2c4ef @16340ea3 I'm not sure how useful this is, but here's a photo of a Rev "A" SunRem board I saw on eBay a while ago - a little different layout. https://files.mastodon.social/media_attachments/files/111/135/679/236/105/994/original/164286e51335cd00.jpg
An #AppleLisaClone side note: this may be a source for the weird open-side expansion board edge connectors. https://edac.net/series/737?fid_p=56&fid_8784=Dual+Row&fid_8785=P.C.+Tail&fid_8788=.550%22+%2813.97mm%29+Notched+Ends Mouser has the high-point contact short-tail version in stock. Almost $10/ea! O.o https://www.mouser.com/ProductDetail/587-737-056-525-206
I asked VintageMicros what kind of memory should be used in the SunRem 2MB RAM card. They sent this picture of SIMMs. The top module looks like the chips are NEC D41256L-12. The sticker says 70ns but doesn’t the -12 denote 120ns? #AppleLisaClone #RetroComputing https://files.mastodon.social/media_attachments/files/111/133/214/933/582/592/original/d5ddfac8bed913f7.jpeg
@8ff2c4ef It looks like the stickers might be from a reseller ... as far as I'm aware -12 is 120ns.
