Upgrading Powerbook 190 to 68040 with FPU?

D

DominBear

New Tinkerer
Jul 18, 2025
8
4
3
Can it be done?
I tried installing MC68040FE33V but no chime. CPU gets warm so it does something? Soldered LC back, works again.
Does the ROM care about it? They are pin compatible and the only difference should be FPU?
 
I recall reading somewhere about someone else doing this successfully, ...and something about only specific CPU part numbers working in Macs. Was it a 5V vs 3.3V thing?


PowerBook 500 Series full 040 CPU swap

You definitely should! I’m guessing this mod could be applied to the 190 and the Duo 280c. I was thinking that too.. actually I’m thinking if you took a 190 and replaced its screen with an active one from a 5300 (maybe even a CE?) and gave it a full 68040 you’d pretty much have the best...
68kmla.org 68kmla.org

I think these are saying you need one of these:

MC68040FE25A
MC68040FE33A
MC68040FE40A


and that the ends in V version actually doesn't have an FPU and is 3.3V not 5V.
 
I have successfully done it on a PowerBook 540c and a PowerBook Duo 280c. @croissantking is the first I saw do it successfully (the above link is to his thread) on his 540c which is what inspired me.

Never tried on a 190.
 
I tried these CPUs https://www.ebay.com/itm/226944137012

68040.jpg
 
Ah crap. It looks like V is 3.3V part. So I probably fried it a bit ;-)
I guess I need to find 5V part and try again.
 
DominBear said:
Ah crap. It looks like V is 3.3V part. So I probably fried it a bit ;-)
I guess I need to find 5V part and try again.
Click to expand...
It may not have burned as it can accept 5V input, though VCC should be 3.3V.
However V part don't have FPU - even if they are not labelled LC.
Quoting appendix C of the '040 UM:
• For the MC68040V, all differences that exist between the MC68LC040 and the
MC68040, as described in Appendix A MC68LC040, also apply to the MC68040V.
For the MC68EC040V, all differences that exist between the MC68EC040 and the
MC68040, as described in Appendix B MC68EC040, also apply to the
MC68EC040V.
• Both devices operate to 0 Hz and can accept 3.3V or 5V input.
Click to expand...
They also have three extra signals so the pinouts is not 100% identical to non-V in QFP packages.
 
Fizzbinn said:
I think these are saying you need one of these:

MC68040FE25A
MC68040FE33A
MC68040FE40A
Click to expand...

Yes, those are the correct part numbers for the K63H and L88M masks.

E42K is MC68040FExx (no suffix)
E31F is XC68040FExxM

Genuine chips also have their speed rating printed under the part number eg ‘66/33 MHz’.

Here are some examples:

IMG_5502.jpeg


Fizzbinn said:
and that the ends in V version actually doesn't have an FPU and is 3.3V not 5V.
Click to expand...

Yes, this is correct - no FPU.

A valiant effort OP - I don’t think anyone has done the FPU upgrade on a 190 yet.
 
Last edited:
Lessons of today.
1. somehow my trackpad stopped working. tried another one and still nothing.
2. replaced PMIC with another one desoldered from another PB190 board, one was SC428002 the other SC428006. Learned they are no direct replacements. The trackpad still didnt work but with replacement PMIC there was screen corruption related to mouse cursor. Therefore it seems the cursor is managed and rendered in VRAM by PMIC. One both PMICs use 32KB SRAM, but one uses 55ns and the other 70ns. Maybe that matters. Anyway, replacing PMIC didnt solve my trackpad problem, but going back to original fixed the corruption. The good news is SRAM for PMIC matches what atari portfolio uses so i can harvest the chips from dead boards for spares for portfolio ;-)
3. I think the trackpad connector works fine, i beeped most connections to trackpad PCB. so why doesnt it work? i have inspected the board few times i dont see any shorts/bridges etc.
4. how the hell do i get external zuluscsi slim working on this thing, or any external scsi thing? i tried hdi30->db25 adapter, hdi30->hd50 adapter with scsi/dock switch and hdi30-db25 cable,. if give zuluscsi external usb power. but it doesnt even start or write anything to log file with debug enabled. tried plextor scsi cdrom drive and neither of my 2 pb190s sees it either. so what is the secret how do i get external scsi going?
 
Wayyyback in the day, some compatible chips became available. Folks at the MLA snapped them up, keen on doing something silly with them like installing AUx or some such. Try searching there. Might even be as old as the Snitz Archive?
 
DominBear said:
And the lesson is pb 5300 and 190 touchpads are not interchangeable
Click to expand...
The entire power management system is different between those models. You can replace the 190's horrific trackpad with the lovely Duo TrackBall assembly because there's clearance available underneath evil pad, whereas the 5300 is filled to the brim of that cubic with the larger power kluge.

One of these days I'll have to get around to modeling the button surround for it to complete that hack now that printing technology has caught up with my stalled project.

I'll have to pull it out for a photo session?
 
I kind of like the trackpad.

Well round 2. My Amazon 68040 purchase from China has arrived. Soldered the CPU, it booted couple times. Ran Tattletech and Speedometer.
Neither reported FPU present. Then after Speedometer benchmark wchich returned the same results as before, the machine froze and didnt boot again anymore. So I guess I got a rebadged LC and 25MHz one that probably fried itself.
 
DominBear said:
I kind of like the trackpad.
Click to expand...
They're OK if you accept them for what they are, but they cannot compete with modern trackpads.

DominBear said:
Well round 2. My Amazon 68040 purchase from China has arrived. Soldered the CPU, it booted couple times. Ran Tattletech and Speedometer.
Neither reported FPU present. Then after Speedometer benchmark wchich returned the same results as before, the machine froze and didnt boot again anymore. So I guess I got a rebadged LC and 25MHz one that probably fried itself.
Click to expand...
Beware fakes! They're everywhere!

Finding a genuine 68040 is quite difficult, from what I've read, and many so-called 66/33 '040s with FPUs are actually fraudulently remarked 25/50 68LC040s. Many of those were probably cooked almost to death when they were reclaimed and remarked, too, so if one tried to use one, it either would work for a short time and then fail (as yours did) or be DOA and not work at all.

There are one or two reputable sources that I'm aware of (new reliable sources get discovered from time to time, but they usually go out of stock fairly quickly because their inventories are usually fairly small). The costs are often higher, sometimes significantly, but you do get what you pay for, because they're usually either genuine NOS, or carefully salvaged REAL chips that have been tested to ensure that they operate as advertised.

c
 
@jmacz Nice to see you over here! I'm expanding my territory a bit, as you can see.

After the last outage interrupted an important conversation, I decided it might be a good idea to diversify.

So you'll start seeing more of me here hopefully :)

c

EDIT: Hey! I can do this here!! Come back and edit a post from like a day ago!

I just wanted to add that I did sign up relatively early on (December 2021), but I wasn't particularly active. I'm not a new member, exactly. Just not a frequent visitor. This probably goes without saying, but I wanted to clarify.
 
Last edited:
  • Like
Reactions: Paralel, jmacz, Kai Robinson and 1 other person
You must log in or register to reply here.
Top Bottom
Back