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randomblame

macrumors newbie
Original poster
Dec 6, 2021
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I attempted to populate the empty memory and capacitor traces on the ibook g3 usb model, unfortunately I was unsuccessful in getting it to recognize the extra memory. I tried several other things like populating missing resistor positions and I fiddled with it as best as I could without any sort of schematic. So the next possibility I'm considering is replacing the existing memory with higher capacity chips - anyone have any ideas on what I might be able to find



















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ervus

macrumors 6502
Apr 3, 2020
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That looks like a nice effort! Do you know if there's a version of that logic board that comes with populated RAM that you can copy? If you look at schematics for other powerbooks, there may be a couple extra connections to distinguish between one socket and another, and you may have to make similar connections to enable the second bank you installed. Just a guess...
 
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randomblame

macrumors newbie
Original poster
Dec 6, 2021
7
7
the problem is that they didn't ship a version with those populated so it's all guesswork I have a set of 256mbit 32x8bit chips on the way to try next in case the issue was that these chips don't match the existing ones also that should hopefully get me to 128MB of onboard storage with only the 4 chips that are populated now so possibly an improvement either way
 

ervus

macrumors 6502
Apr 3, 2020
414
311
It would be neat if you can get it working. I'm not sure how regular RAM modules are detected, but there's usually a little SPD memory chip that has some info stored on it. So with built-in RAM that stuff may be coded directly in the firmware. Hopefully apple's anti-upgrade policy does not extend to hard-wiring the firmware to reject bigger/more RAM chips.
 
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the problem is that they didn't ship a version with those populated so it's all guesswork I have a set of 256mbit 32x8bit chips on the way to try next in case the issue was that these chips don't match the existing ones also that should hopefully get me to 128MB of onboard storage with only the 4 chips that are populated now so possibly an improvement either way

This was the very thing which got me to sign up for the MR forums in 2018.

The unused RAM slots was something I wanted to explore on my own, but I lacked the technical know-how and the soldering finesse to attempt it. In the time since, I’ve removed four RAM chips from another, long-dead Rev. C board last year and I set them aside, mindful how I’d need more than just those (such as transistors, capacitors, and resistors related to the memory bus) to have an even chance of breaking that barrier.

I speculated then — and maintain still — that Apple had planned forward back during the 1998–99 board/industrial design process with the prospect of eventually populating those spots on the board as a final revision before moving on to another board and form factor (e.g., a “Rev. D” edition, replete with its own unique colours).

But given the polarizing reactions from Apple faithful at the time that the clamshell iBook form factor looked like a toilet seat, a makeup compact, and a child’s toy, I suss that Apple forwent releasing one more revision in lieu of just rolling out a conventional form factor from May 2001 onward — which we came to know as the basic form factor they stayed with until the move to MacBooks in 2006.

That said, I also don’t know whether Open Firmware version 4.1.7f4 — the final revision for the Rev. C models (the only series I’d ever seriously explore attempting to use those RAM chip locations) — even knows to be aware of a third bank of RAM chips on that board.

In short, there are the physical logistics of finding out how those locations on the board were to be purposed (you’ll need to get your hands on the schematics for the Rev. C iBook clamshell, which are, reportedly, out there, but I’ve been wholly unsuccessful in pinpointing them personally). I also don’t know how the system might respond to simply using higher density chips sourced from, say, a PC66/100/133 SO-DIMM, sharing the same form factor.

Nevertheless, I’ll keep my eye on this thread and on your work, because you’re already much further along already than I ever got and I’m learning with you as you go along. I am also applauding your trial-and-error efforts! ?



EDIT TO ADD: Incidentally, I noticed there isn’t an IC on U34, on either of your board pics. Without schematics or even referring to the board from a ice dual-USB iBook from May 2001 (as I think the generational changes are incremental), it’s not clear what those eight connection points are related to, but a working hypothesis is it might be needed for recognizing, managing, and/or delegating memory tasks to a third bank of onboard RAM.

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randomblame

macrumors newbie
Original poster
Dec 6, 2021
7
7
yes u34 has been speculated to possibly be for a spd chip for the other memory bank but it's not existent on the revision with firewire which also has the unpopulated memory traces. Another thing I had looked at was the cache sram and replacing it with http://www.datasheetdir.com/KM736V887+SRAM I already have the g4 installed :D I expect to receive my memory ics from mouser tomorrow so I'll update when I know more

additionally I found that BCM5221A is pin compatible with the bcm5201a ethernet controller and I am investigating if bcm5231 is also (gigabit!) and I may play with swapping out that ethernet controller.
 
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randomblame

macrumors newbie
Original poster
Dec 6, 2021
7
7
u34 is for a qspi eeprom that contains spd data. I transplanted both from the firewire parts boards I have as well as all of their samsung memory chips and I'm still just getting the 3 beep memory error *sigh* the device does read the new qspi chips because if backwards it will not boot at all so that's something. I also did not have luck booting the 256mbit chips that came in the mail in either or both banks. lots of microsoldering my eyes hurt
 
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yes u34 has been speculated to possibly be for a spd chip for the other memory bank but it's not existent on the revision with firewire which also has the unpopulated memory traces.

You’re describing the Rev C. iBook — the 366/466 models with FireWire. My daily runner is a 466MHz version, while I sourced the chips from a 366MHz FW board.

I’m not sure what “SPD” is short for, though.

Another thing I had looked at was the cache sram and replacing it with http://www.datasheetdir.com/KM736V887+SRAM I already have the g4 installed :D I expect to receive my memory ics from mouser tomorrow so I'll update when I know more

Yeah. That’s one of the benefits of the pre-FireWire PPC750L socket boards. The only path for CPU upgrade for me is to source a 700MHz PPC750CXe chip from a dead “Summer 2001” iMac G3 SE board.

additionally I found that BCM5221A is pin compatible with the bcm5201a ethernet controller and I am investigating if bcm5231 is also (gigabit!) and I may play with swapping out that ethernet controller.

Keep us posted!
 

randomblame

macrumors newbie
Original poster
Dec 6, 2021
7
7
I seem to have been mistaken about the memory configuration. For some reason I must have pulled up the wrong datasheet. The memory that was on this board (usb board) was K4S281632B-TL1L

data sheet here

and the memory that was on the firewire board was MT48LC8M16A2P

both ic's are 16 bit chips and I tried replacing it with the 8 bit zentel chips which might have very well been incompatible. I'll have to try again with 16 bit memory like this 512mbit option

or this 256mbit option


My next step is to attempt to graft the memory ic's from the 2001 ibook g3 M8597LL they are 16 bit 256mbit I have a donor board on the way for that, I couldn't help but to pick it up on fleabay it's so closely related and yet slightly newer. It even includes the bcm5221a I had mentioned earlier as an upgraded ethernet possibility
 
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LightBulbFun

macrumors 68030
Nov 17, 2013
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London UK
this is very cool to see! I had wondered about what the upgrade possibilities where RAM wise when I was doing my Clamshell iBook G3 to G4 CPU upgrade :)

one thing that might help with regards to figuring out what needs configuring is while I dont have schematics to the iBook G3 clamshell itself sadly, I do however have a link to schematics for a later iBook G3, which does also use SDRAM so may still be of use :)

 
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this is very cool to see! I had wondered about what the upgrade possibilities where RAM wise when I was doing my Clamshell iBook G3 to G4 CPU upgrade :)

one thing that might help with regards to figuring out what needs configuring is while I dont have schematics to the iBook G3 clamshell itself sadly I have schematics to a later iBook G3, which does also use SDRAM so may still be of use :)


Hot diggity I love seeing schematics for the old stuff finally surface. :D
 

randomblame

macrumors newbie
Original poster
Dec 6, 2021
7
7
That's so useful thanks! One thing that really stands out in that schematic is the bom option table for the memory chips, this particular board supports 4 16mx16 chips or 4 32mx16 chips for a possible 256mb onboard
 

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randomblame

macrumors newbie
Original poster
Dec 6, 2021
7
7
the 256mbit tsop chips from the 2001 ibook g3 allowed the device to boot to the question mark only and not into open firmware, I swapped the spd eeprom with the later ibook as well and it made no difference. I attempted to swap the motorola microcontroller (which has it's own small amount of persistent memory) with the later revision as well but the traces under it were very fragile and tore so I'm in the market for another first gen clamshell board I think
 

LightBulbFun

macrumors 68030
Nov 17, 2013
2,900
3,195
London UK
the 256mbit tsop chips from the 2001 ibook g3 allowed the device to boot to the question mark only and not into open firmware, I swapped the spd eeprom with the later ibook as well and it made no difference. I attempted to swap the motorola microcontroller (which has it's own small amount of persistent memory) with the later revision as well but the traces under it were very fragile and tore so I'm in the market for another first gen clamshell board I think
if you can boot to a question mark then that is OpenFirmware :) its just a simple OF program

you can hit Control Z to exit out of it which will drop you to an OF prompt :)
 
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