68kMLA Classic Interface

This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.

Click here to select a new forum.
Macintosh Classic II, FPU / Math Card (Picture)
Posted by: uniserver on 2013-04-16 10:55:56
Posting this only because i have never seen one yet, until now.

Screen shot 2013-04-16 at 1.46.16 PM.jpg
Posted by: mcdermd on 2013-04-16 11:06:39
Oooh - very nice! Any pictures of the other side?
Posted by: uniserver on 2013-04-16 11:12:43
nope just the one picture 🙂

Posted by: bbraun on 2013-04-16 19:07:24
May as well link the source.
Posted by: uniserver on 2013-04-16 19:46:38
I'm not going to lie, The little kid in me wants that all for my self, that is why i did not post the ebay link.

I think my 2 year old is rubbing off on me ;-)

Posted by: uniserver on 2013-04-16 20:45:40
by the way, the seller is a cool dude.

He shot a pic of the rear for me 🙂

Screen shot 2013-04-16 at 11.41.19 PM.png
Posted by: mcdermd on 2013-04-16 21:20:12
Well that is interestingly simple, no?

sonnet_FPU.jpg
Posted by: Macdrone on 2013-04-16 21:54:27
With a classic memory module an fpu and some time could you recreate it?
Posted by: uniserver on 2013-04-16 22:32:38
2 caps, some wire wrap, and a FPU and one could re create it. 🙂

interestingly simple, Yes.
Posted by: Macdrone on 2013-04-17 01:13:14
So ill send you a memory and fpu and you can make it happen after you buy it?
Posted by: uniserver on 2013-04-17 05:41:29
haha, i dunno 🙂

Posted by: uniserver on 2013-04-18 09:26:27
from the seller, Info on the 2 caps on there.

One side reads K5M the other reads 104
Posted by: uniserver on 2013-04-18 09:39:28
A little info on those caps.

http://www.picaxeforum.co.uk/showthread.php?15901-K5M-104-Capacitor-Polarity

104 is indeed .1uF as Premelec
Posted by: MinerAl on 2013-04-19 10:20:58
Still need to know what's going on under the chip, and the connector.

Buy it and dissect it!
Posted by: uniserver on 2013-04-19 10:30:19
Some bidder sniped it and won it for a dollar over my max bid.

My max bid was 41 bucks. I did not want to pay over that,

I already have the wire wrap, I have those caps in-stock, I have a 16mhz FPU.

I will solder the wires right to the header on the motherboard.

maybe get a little hobby pcb from the shack, to set the FPU on.

I don't have the time to do this now, but it appears less complicated then the InternalHardDriveinaPluShAcK™lol
Posted by: bbraun on 2013-04-19 14:09:53
FWIW, the ClassicII dev note has the pinout of the connector. It's pretty much just directly throwing the 68882 on the bus, with the only trick being the 16 bit bus, so doubling up the data lines and using the /DSACK 0 & 1 signals.

I've put some labels on those pictures, to illustrate. For the most part, the labeling refers to the 68882 pins, not necessarily the Classic2's connector. For instance, D16 on the Classic2's connector goes to D0 on the 68882, and I've labeled it D0:

c2fpu.png

c2fpufront.jpg

You can also put a ROM in that socket, up to 3MB worth.
Posted by: uniserver on 2013-04-19 14:14:49
you are the F'in man!
Posted by: MinerAl on 2013-04-19 20:04:30
You can also put a ROM in that socket, up to 3MB worth.
So, you could put a little 7.x boot image in ROM and do the Classic trick in a Classic II?
Posted by: bbraun on 2013-04-19 20:33:32
I'm really not sure about that. I haven't looked at the ClassicII ROM in particular. There's a good chance it has the EDisk driver, which is what the Classic used to boot (also RAM disk driver, and pcmcia flash card in laptops). That driver looks over some set of addresses (I don't recall how it determines that), for a valid header. So, it might be possible you could put a valid EDisk driver's ROM disk image into ROM there and have it automagically bootable.
1 >