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Iisi issue
Posted by: imactheknife on 2026-06-09 17:08:35
Feeling lazy tonight lol.. so picked up a iisi logic with rom simm slot. It has rom on board as well. It is recapped, nothing major that i could see. It turns on, chimes and then gets death chimes. Screen comes on for a second when first turned on, then nothing, stays black.

On a side note: will an apple se/30 rom simm work in the iisi? Thanks for any info, and excuse my laziness in searching!
Posted by: croissantking on 2026-06-09 18:21:53
Feeling lazy tonight lol.. so picked up a iisi logic with rom simm slot. It has rom on board as well. It is recapped, nothing major that i could see. It turns on, chimes and then gets death chimes. Screen comes on for a second when first turned on, then nothing, stays black.

On a side note: will an apple se/30 rom simm work in the iisi? Thanks for any info, and excuse my laziness in searching!

Might be bad ram.
SE/30 rom won’t boot a IIsi.
Posted by: imactheknife on 2026-06-10 03:04:57
Might be bad ram.
SE/30 rom won’t boot a IIsi.
Will iivx onboard ram be the same? I assume it would be. I also have a spare classic board around and a duo 210 board.
Posted by: mikes-macs on 2026-06-10 03:12:34
So on the Mac IIsi there need to be a jumper on W1. This will disable the onboard ROM and allow the use of the ROM SIMM


Is your ROM SIMM a genuine Apple ROM or Custom ROM?
Posted by: imactheknife on 2026-06-10 03:27:33
So on the Mac IIsi there need to be a jumper on W1. This will disable the onboard ROM and allow the use of the ROM SIMM


Is your ROM SIMM a genuine Apple ROM or Custom ROM?
Only rom i have is a se/30 rom which i guess wont work. So back to checking bad ram first.
Posted by: croissantking on 2026-06-10 03:27:56
Will iivx onboard ram be the same? I assume it would be. I also have a spare classic board around and a duo 210 board.

IIvx has 4MB onboard (512k per chip) so is not the same since the IIsi has 1MB.

The Classic has the same 1MB onboard (128k per chip).

FYI you can upgrade the IIsi to 4MB so you could use the IIvx as a donor if you change all the chips.

So on the Mac IIsi there need to be a jumper on W1. This will disable the onboard ROM and allow the use of the ROM SIMM


Is your ROM SIMM a genuine Apple ROM or Custom ROM?
He doesn’t have a rom simm, he said it is onboard.
Posted by: imactheknife on 2026-06-10 03:28:37
Some pictures..
Posted by: imactheknife on 2026-06-10 03:29:35
IIvx has 4MB onboard (512k per chip) so is not the same since the IIsi has 1MB.

The Classic has the same 1MB onboard (128k per chip).

FYI you can upgrade the IIsi to 4MB so you could use the IIvx as a donor if you change all the chips.


He doesn’t have a rom simm, he said it is onboard.
Oh interesting. So i do have a donar iivx board. So can definitely upgrade the memory
Posted by: croissantking on 2026-06-10 03:33:58
Oh interesting. So i do have a donar iivx board. So can definitely upgrade the memory

Yep. Not saying it’ll fix the death chimes but since you’re changing chips anyway you might as well upgrade.

Some discussion here:
tinkerdifferent.com

Upgrading IIsi onboard RAM to 4MB

The Mac IIsi motherboard is wired for a 1 MB onboard RAM array using eight 256kx4 DRAM chips or a 4 MB RAM array using eight 1Mx4 chips. After discovering this on my broken IIsi, I was able to simply replace the eight RAM chips with larger 1Mx4 RAMs (e.g. KM44C1000, M5M44400, MT4C4001) and get 4...
tinkerdifferent.com tinkerdifferent.com
Posted by: imactheknife on 2026-06-10 03:40:54
Yep. Not saying it’ll fix the death chimes but since you’re changing chips anyway you might as well upgrade.

Some discussion here:
tinkerdifferent.com

Upgrading IIsi onboard RAM to 4MB

The Mac IIsi motherboard is wired for a 1 MB onboard RAM array using eight 256kx4 DRAM chips or a 4 MB RAM array using eight 1Mx4 chips. After discovering this on my broken IIsi, I was able to simply replace the eight RAM chips with larger 1Mx4 RAMs (e.g. KM44C1000, M5M44400, MT4C4001) and get 4...
tinkerdifferent.com tinkerdifferent.com
Oh ok, i remember that thread now. I actually commented on it lol.. so yeah will see.
Posted by: mikes-macs on 2026-06-10 03:47:19
Oh I missed that part, thought the SIMM was populated.
Posted by: Durosity on 2026-06-10 05:01:41
I had exactly this issue with one of my Iisi boards.. turned out to be one of the oscillators.. I think G4?
Posted by: croissantking on 2026-06-10 05:06:46
Oh ok, i remember that thread now. I actually commented on it lol.. so yeah will see.

I re-read the thread and Zane (the OP) was saying he doesn't recommend the mod, as it reduces performance if using onboard video. Bank A which the video uses is performance constricted so it's better to keep it to 1MB. You want all your apps to be in Bank B.
Posted by: imactheknife on 2026-06-10 06:14:32
I had exactly this issue with one of my Iisi boards.. turned out to be one of the oscillators.. I think G4?
Ok, will look into that .
Posted by: imactheknife on 2026-06-10 18:36:12
I had exactly this issue with one of my Iisi boards.. turned out to be one of the oscillators.. I think G4?
Replaced g4, no dice. Tried replacing one memory ic no dice. Guess i will have to try them all and see. Argh! Lol cant find my spare classic board. Will any of these chips work?
Posted by: croissantking on 2026-06-10 19:50:18
Replaced g4, no dice. Tried replacing one memory ic no dice. Guess i will have to try them all and see. Argh! Lol cant find my spare classic board. Will any of these chips work?

Did you already swap in all the RAM from your IIvx, upgrading it to 4MB?

If so, you can use the 424410 chips (because they are 4 bit chips) but not the 424100 chips (because they are 1 bit chips). Eight chips need to add up to 32 bit (the width of the data bus) hence you need to use 4 bit chips.

Otherwise, your IIsi still has 1MB onboard and neither of these chip types is suitable. You'll need to find 128k chips that are 4 bit wide.
Posted by: imactheknife on 2026-06-11 02:37:59
Did you already swap in all the RAM from your IIvx, upgrading it to 4MB?

If so, you can use the 424410 chips (because they are 4 bit chips) but not the 424100 chips (because they are 1 bit chips). Eight chips need to add up to 32 bit (the width of the data bus) hence you need to use 4 bit chips.

Otherwise, your IIsi still has 1MB onboard and neither of these chip types is suitable. You'll need to find 128k chips that are 4 bit wide.
No havent tried that yet. I have them ready to go. I just thought i would go more original if i could pull some chips from a memory stick. I can’t find my classic parts board which ticks me off lol.. too much stuff
Posted by: imactheknife on 2026-06-12 17:06:24
So changed all the memory to correct memory, and all the als245 and still the same thing. Any idead what else? Probably a broken trace at this point or something else?
Posted by: croissantking on 2026-06-12 17:07:13
Which chips did you use?

Yeah I reckon broken trace
Posted by: imactheknife on 2026-06-12 17:26:18
Which chips did you use?

Yeah I reckon broken trace
I ended up going through my drawer of misc 30 pin ram and found a classic expansion card. The soldered on ram was the same # as the iisi board so i went for it.
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