Mac LC III 16mhz?

[techknight]

I just picked up a macintosh LC III and it works ok, although the capacitors are failing.

What i noticed, is everwhere i read the macintosh LCIII has a 25mhz 030. Mine has the exact logic board an LCIII would have, but it has a 16mhz 030.

Any ideas why?

 

[LCGuy]

I have no idea...no LCIII ever shipped with anything less than a 25 Mhz 68030. Are you sure that its actually an LCIII board and not an LCII board? If its an LCIII board, it will have an FPU socket and one RAM slot for a 72 pin SIMM, as well as an enhanced LC PDS slot. If its an LCII board, it will have solder pads for an FPU socket, but no actual socket, and two RAM slots for 30 pin SIMMs, and a standard LC PDS slot.

Unless by some chance its a prototype, this is the only way I can figure as to how an LCIII would end up with a 16 Mhz '030, since all the boards between the LCII, LCIII and LC475 are completely interchangable.

 

[beachycove]

Possibilities:

1. God sent you this rarity so that you could sell it for lots of money on eBay (genuinely a one-off) and give the proceeds to the poor.

2. What LCGuy said - it's not an LCIII.

 

[techknight]

I did a youtube video on this machine. best way for me is to get pictures of it.

Anyway, yes its an LCIII as it has 1 ram slot, and an FPU socket.

 

[techknight]

Here is the picture: last time i checked the MC68030FE16B was a 16mhz clocked processor.

Full size:

http://0ki.info/uploads/919e9798d5.jpg

thumbnail

 

[techknight]

system running pic:

http://0ki.info/uploads/26e4ef999e.jpg

 

[Mars478]

That's quite something. You've got an amazing machine there. Keep it and guard it with your life.

Or sell it quick.

 

[LCGuy]

Thats really quite strange, thats definitely an LCIII board, but no LCIII was ever sold with anything less than a 25 Mhz 68030, and yes, thats definitely a 16 Mhz '030, otherwise it'd have a MC68030FE25B.

I dunno, the only thing I can think of is that Apple did a limited production run of 16 Mhz 68030s in one country because it would have cost too much to sell 25 Mhz LCIIIs there....thats really the only thing I can think of. Apart from the fact that it has the 16 Mhz chip, the board certainly looks identical to a regular production board.

 

[Mars478]

Yeah I don't see any telltale signs of proto boards. Looks fine.

The only thing might be the Reset label... Just two pads.

 

[LCGuy]

Those solder pads are in all production model LCIIIs, no LCIII that I've seen ever had a switch there, just the solder pads.

 

[techknight]

its definately strange. thats the first thing i noticed when i opened it up. seen the 16mhz CPU, and was like, what the heck?

Me hurrying up and sell it for one fluke? or think it just became extremely valuable for one fluke? not a chance. im not here for the selling money game. im here to play with these things. ive had LCs when i was a kid and i wanted to get another one to monkey around with.

also there isnt any telltale signs that it came from another country either, as it looks like a plain english install. the volume creation date is 1999

it also might be a 16mhz IC overclocked to 25mhz stock osc speed. reason why i think this is becuase the chip gets extremely hot. hotter than comfortable. but it runs ok without a heatsink. Any kind of program out there like apple system profiler would tell me what its running at?

 

[Nathan]

Well, I'd say either look for a normal LCIII motherboard or seek someone out with a broken LCIII board with a working CPU and get the chips swapped. It really shouldn't matter since an normal 16MHz '030 in a LCIII should outperform one in an LCII since the LCII has that 32-bit? processor on a 16-bit motherboard (address/data bus?) where as the LCIII should have a 32-bit motherboard (address/data bus?).

 

[MacJunky]

You should benchmark it just for fun.

 

[techknight]

well i dont have the software to do it, so if someone would point me in the proper direction that would be appriciatd.

 

[johnklos]

http://eshop.macsales.com/Tech/index.cfm?load=newertech.html

You can download the NewerTech Gauges from that page.

 

[techknight]

ok. someone sent me a pm also with a couple benchmark utils. so i am going to try them and see what happens i guess.

 

[techknight]

anyone have a copy of macbench 1 and 2? seems the ones sent to me in PM are garbage. they dont open/corrupted.

 

[Strimkind]

Did you ever get the gauges to work?

 

[beachycove]

Further to this one:

In a box of components that I am putting on eBay, I came across a small AIO logic board with a 68030 marked 16MHz, and assumed it was a Color Classic. I took it out to pop in a Color Classic for testing, got my two 30-pin SIMMs out, and proceeding to put them in ... discovered that it took a 72-pin SIMM. It was from an LC5xx machine.

For obvious reasons, I fired it up, and discovered that it runs at 25MHz. It is not an exact match for my other LC520 logic board (presently being auctioned, and which is marked as having a 25MHz chip), but it runs at the faster speed and works perfectly in the Color Classic (which thinks it's a Color Classic II in the diagnostics software used to test the components, despite its running at 25 rather than 33 MHz). I confirmed the speed with Gauge Pro, Apple Personal Diagnistics and MacCheck.

Thinking this was rather interesting, I then compared the chip markings on the two logic boards tested, and discovered this:

Color Classic @ 16MHz:

MC 68030FE16B

04D66C

QEWD9325

MALAYSIA

LC5xx @ 25MHz:

MC68030FE16B

04D66C

QEWV9250

MALAYSIA

Assuming the last line is a date code or something, they're surely the same.