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PowerBook 540c, PowerPC upgraded — can downgrade?
Posted by: Amy Worrall on 2015-09-18 05:56:23
I bought a PowerBook 540c on eBay, because I wanted a 68k laptop. When it arrived, I discovered it had been upgraded to PowerPC.

I have two questions:

1. Would it be possible to downgrade this Mac by buying a 68k CPU or motherboard? (I'm not sure how much hardware the PPC upgrade changed.) There are a few of each on eBay.

2. What is the earliest OS that the PPC-upgraded PowerBook 540c could run? It's currently on 8.1 — will I run into any problems if I try installing an older system?

I have a set of original floppies that came with the 540c, which I suspect contain System 7.1. I imagine they won't work, because the CPU upgrade is newer than the floppies, correct? 

I'd love to get 7.5 on there if I can.

Thanks for your help,

Amy
Posted by: techknight on 2015-09-18 06:59:48
You can downgrade it by purchasing a replacement 040 card from ebay, they are up there from time to time. 

Then, you can re-sell the PPC upgrade on ebay, and it would likely go for a little bit of coin, as they are not very common. 

It can run Mac OS 9 with a hack or two, BUT it would be horrifyingly slow. Not to mention RAM limitations the 5XX has. 
Posted by: Amy Worrall on 2015-09-18 07:11:00
Something like this?

http://www.ebay.co.uk/itm/Apple-33-MHz-68LC040-CPU-for-PowerBook-520-540-/160709816022?hash=item256b0d2ed6

Regarding the OS, I want older rather than newer — 7.5 would be great 🙂

Posted by: techknight on 2015-09-18 11:19:48
yep. Thats the one. 

Then you can re-sell the PPC upgrade if you wish, and likely make back the cost of the CPU card and the 540. 
Posted by: MikeatOSX on 2015-09-18 14:34:15
Something like this?
You've got a PM.
Posted by: uniserver on 2015-09-19 07:57:49
yeah the PPC upgrade is rare and in demand. lol.

that is why the seller has 5 of them for sale.  well that and the plastics of these things completely disintergrate.

I waited 2 years to find one for my PB 540c.  its a massive upgrade!
Posted by: techknight on 2015-09-19 08:02:51
I didnt think the 5XX was as bad as the 1XX stuff, but I guess it is, that front piece constantly falls off. 
Posted by: uniserver on 2015-09-19 08:21:10
well specifically the portable and the powerbook 100, seems to still have pretty good plastics. but starting with the Powerbook 140+ is when they get like balsa wood.
Posted by: techknight on 2015-09-19 09:57:08
Its funny too, because the compaq LTE from the same time period as the powerbook 140+ series, all have decent plastics. 
Posted by: aplmak on 2015-09-21 19:02:52
Yes that stupid front piece is always an issue.. and that stupid plastic thing above the processor is a pain in the @$Q#.. It breaks if you screw in the top screws too much.. I loved my 540c... I can't even remember when I sold it... I had gotten the Rev C PCMCIA module at the time.. Since I worked in the Apple tech room I ordered ALL the plastics for it at the time... I had boxes and boxes... I gave them away..  I bought another 540c recently to fix up and rekindle my aspiration for the 500 series.. I saved my NewerTech PPC upgrade board.. Still got it!!! In the box!!!! I found my receipt for it.. like $700.00 at the time!!! So Mike your right you don't see them that often and he's lucky his came with one.. He can get a few bucks for it!!!
Posted by: Paralel on 2015-09-23 17:32:39
I traded my 5XX PPC upgrade to Uni for all the TLC on my Classic II. Excellent trade.

I'm glad I did, since I finally got my hands on a 550c CPU daughterboard. Not too many Powerbooks here in the US that run a full '040
Posted by: Comodín on 2015-10-25 08:53:13
I also bought a Powerbook 540c yesterday and I was wondering how I can find out if mine has a PPC upgrade or not, preferably without opening the machine. The only spec I see is that it has 20,480k of total memory and Mac OS 7.5.3 installed.
Posted by: Amy Worrall on 2015-10-25 09:22:33
I also bought a Powerbook 540c yesterday and I was wondering how I can find out if mine has a PPC upgrade or not, preferably without opening the machine. The only spec I see is that it has 20,480k of total memory and Mac OS 7.5.3 installed.
Hmmm. I used System Profiler, but that didn't ship until MacOS 7.6…

I can't remember this for definite, but I think there were some memory differences. Was the Modern Memory Manager PowerPC only? If so, if it's present in the memory control panel, you're on PPC. Also, I believe on PowerPC, the suggested memory allocation of apps is smaller when virtual memory is turned on, compared to when it is turned off… but I can't remember if this only applies to native apps or if it's all of them.

Sorry I can't be of more help, I'm trying to remember this stuff from years ago 🙂

Amy

P.S., here's me using my 540c to present a talk at NSScotland:
Posted by: techknight on 2015-10-25 09:41:42
thats cool as hell. 
Posted by: MikeatOSX on 2015-10-25 15:41:29
how I can find out if mine has a PPC upgrade or not
Speedometer 4.0.1 etc.

TechTool 1.2.1

B)

Posted by: uniserver on 2015-10-25 17:09:27
yeah that is pretty awesome right there.
Posted by: Macdrone on 2015-10-26 00:51:55
This brought to mind movie I just noticed macs in.  Gremlins 2 the secretary has a mac Plus all up and running and next to it with no monitor is a Mac II series with no other parts, no keyboard , no mouse , no monitor.
Posted by: Paralel on 2015-10-26 12:20:48
The Plus seemed to get alot of love on Hollywood sets.
Posted by: Comodín on 2015-10-30 12:51:07
Amy, very awesome! I upgraded my PB to Mac OS 8.0 and looking at System Profiler I'm pretty sure I have the non-PPC: 68LC040 at 33Mhz and total memory of 20MB. I tried to write the images with RawWrite for Windows to a floppy (is there a way to write to floppy's from OS X I have a external floppy drive?), but the 540c won't accept them. It first wants to initialize the floppy and then I get a message that the floppy might be defected, which is very probable.

Another question if I may: this PB has a lot of software on it from its former user, lot of programs don't work anymore, corrupted etc. I was thinking a fresh install would get rid of all this programs but they're still there. What is the best way to get rid of them without making the PB unoperational? Would a fresh install of 8.1 do the trick?
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