Thread

Macintosh Classic II, FPU / Math Card (Picture)

Macintosh Classic II, FPU / Math Card (Picture) Hardware 57 posts Apr 16, 2013 — Jan 30, 2014

#31 Tue, 8 Oct 2013 - 07:15

From what I can tell, you're right, it just needs a few caps, and that's it.

Being able to actually use the ROM capabilities of the slot is very interesting. It would be great to be able to load from ROM like a Classic.

However, as you said, just a card with an FPU socket would be great.

#32 Tue, 8 Oct 2013 - 09:25

the only thing that is slightly strange is that header,

the only 2 guys that i know right off hand that whip up PCB's are:

dougg3

bigmessowires

techknight

if any of these guys wanna whip up a board?

i think mcdermd has the ability, his brother is in the PCB making biz i think.

but he is busier then a worker ant.

i could do it, but i'm more of a stick with with i know type of guy, home brew up something, would end up trying to make a aweful looking but functional prototype thing. Maybe hack off a scsi connector and glue it to a proto board, glue the fpu to the board, and a to b, with those 2 caps/fpu?

#33 Tue, 8 Oct 2013 - 22:05

I think having a socket you can put a custom ROM into is at least as important as having a socket with, or at least for, a 68882. Most older applications never used the FPU because they used to be so rare, but anyone who can download a hacked image might want to be able to plug in a custom ROM.

#34 Thu, 31 Oct 2013 - 13:12

dougg3 could you please make a pcb for this?

also what would be the benefit of having a FPU in a Classic II? /w its crappy 10meg ram limit……

and how many people would want to buy one for their classic II?

I would assume a target price of $45 + shipping would be reasonable?

Can it be done professionally and sold at that target price?

next, bigmessowires, can you make a clone of the current SCSI to Ethernet adaptors that are out there?

i would assume you could get just as much for those as your floppy emu…

that would be the only way for machines like the Plus/ Classic/ Classic II and Portable to get online

#35 Thu, 31 Oct 2013 - 16:46

I just happen to have one of the sonnet fpu cards. Don't have a classic iii to test with, but as simple as this card is - I doubt it could ever go bad. Would be happy to take some high-res photos. Or, make an offer if you want the card itself.

If anyone's interested, shoot me a pm.

#36 Thu, 31 Oct 2013 - 19:45

I just happen to have one of the sonnet fpu cards. Don't have a classic iii to test with, but as simple as this card is - I doubt it could ever go bad. Would be happy to take some high-res photos. Or, make an offer if you want the card itself.
If anyone's interested, shoot me a pm.

$25 plus shipping?

#37 Thu, 31 Oct 2013 - 19:58

Hopefully my PM got to him first

#38 Sat, 2 Nov 2013 - 07:49

Has anyone heard anything from joekster? I sent him a PM, but didn't hear anything. I don't want to keep hoping to get this math card if someone already has worked out a deal with him.

#39 Wed, 6 Nov 2013 - 20:50

Sorry for ignoring everyone, I was busy with the hoard in Tampa. The card was claimed by uniserver, who did send the first PM for it. I got it from an amiga person, who bought it for just the fpu (and pulled it out of. The socket). I'll ask if he has any more, but don't hold any breaths...

#40 Wed, 6 Nov 2013 - 21:35

Congrats, Uni. If you decide not to hold onto it after you're done studying it, let me know.

#41 Thu, 7 Nov 2013 - 01:56

I think the plan is after he's done studying it he'll be making his own!

#42 Thu, 7 Nov 2013 - 02:29

Well, then he won't need the original any longer

#43 Thu, 7 Nov 2013 - 06:43

great news.

a 50 pin scsi cable will connect right to the fpu port(pin for pin) , now all i have to do is make a pinout trash 80 style, get 2 caps, and solder the wires to a fpu.

#44 Sun, 22 Dec 2013 - 04:11

Uniserver, have you had a chance to try this yet? It sounds like a simple enough build that even I could pull it off, so I’m really eager to hear about your results.

#45 Sun, 22 Dec 2013 - 04:35

ok sounds good… go ahead and pull it off… i have not had the time yet for this one.

do it to it!

#46 Sun, 22 Dec 2013 - 05:08

I haven't sent the motherboard and video card for you yet, but if you get one working I would love one, that and your greyscale se30 mod }

#47 Sun, 22 Dec 2013 - 05:15

Sure, sounds good. It’ll make a good project to show the SRCS in the new year. One slight hiccough in the plan, though — does anyone have a compatible 68882 to lend to the effort? I’ll be happy to mail it back afterwards (I have enough caution to solder to a socket, not the chip), but I haven’t any idea what clock speed or what version of the physical package I need. Most VLSI chips came in numerous package types and I’ve no idea where to look for information about it now that this decades-obsolete stuff is getting to be left behind by Freescale’s website. I’ll ask locally too, of course, but I do not anticipate anyone having one (there are few if any Motorola hardware hackers at our meetings just now).

#48 Sun, 22 Dec 2013 - 07:40

Bah, that’s what I get for posting before doing my homework. Turns out the things are only $6 each on Fleabay (with $2 sockets) and any that was ever sold will work just fine in a Classic II, what with its feeble 16MHz bus (no 68882s slower than that were ever sold). The only thing to watch is that if I ever do up a proper design and turn these things into a saleable product I need to stay away from the FN-marked PLCC version. It isn’t lead-free-standards compliant.

I will keep you all posted on my progress. Do not expect great rapidity.

#49 Sun, 22 Dec 2013 - 13:34

Faster fpus will work fine. I bought and put in faster fpus in my color classic. It's a lot like ram in that respect, you can go faster , just not slower. I'll look and see if I have any 68882's around.

#50 Sun, 26 Jan 2014 - 04:04

Still hoping someone can lend a 68882 to the effort. I can probably afford the $2 socket, but $10 for the chip+shipping is a bridge too far at this point (more needed for groceries and gas). Anyone out there feeling helpful?

#51 Thu, 30 Jan 2014 - 18:10

Do you have one yet?

Shipping is a bit prohibitive from/to Canada but I can dredge one up and send if need be.

#52 Thu, 30 Jan 2014 - 18:14

I am pretty sure if someone wants to take a 50 pin scsi cable. cut it and just solder the wires to an fpu socket, then you will have a home brew FPU for your Classic II.

#53 Thu, 30 Jan 2014 - 18:49

...A bit off topic for the 'FPU card' side of it, but AFAIK the expansion slot on the Classic II also handles the external ROM slot as well (up to 1MB IIRC).

If you're designing a board at all, why not include the potential future ROM upgrades by including a ROM socket as well?

I'd love to see a "IIsi" style ROM for the CII in the future...

#54 Thu, 30 Jan 2014 - 19:19

...A bit off topic for the 'FPU card' side of it, but AFAIK the expansion slot on the Classic II also handles the external ROM slot as well (up to 1MB IIRC).

It’s actually 2–3 MiB, varying according to a jumper on the motherboard. The Classic II can have up to 4 megs of ROM, and the jumper determines whether 1 or 2 of those megabytes are on the motherboard.

If you're designing a board at all, why not include the potential future ROM upgrades by including a ROM socket as well?
I'd love to see a "IIsi" style ROM for the CII in the future...

Well, yes, that’s exactly what I’m working towards. See earlier posts in this thread.

#55 Thu, 30 Jan 2014 - 19:29

Do you have one yet?
Shipping is a bit prohibitive from/to Canada but I can dredge one up and send if need be.

Alas, I haven’t had a whisper. And while I am grateful to you for volunteering to lend one of yours, I agree that Canuckistani postal rates are prohibitively expensive. I don’t know the detailed fee schedule but it’d likely be more expensive even than buying one from a US source on Fleabay and putting my address as the destination.

One thing I can say is that any 68882 at all will work — the FN-marked ones may be a problem to resell in a finished product due to RoHS rules, but that hardly matters for a prototype.

#56 Thu, 30 Jan 2014 - 19:34

I am pretty sure if someone wants to take a 50 pin scsi cable. cut it and just solder the wires to an fpu socket, then you will have a home brew FPU for your Classic II.

Broadly correct, but you’d likely want to kludge a decoupling cap or two as well. When you add in the ROM socket on top of that, a real board starts to look like a good idea.

#57 Thu, 30 Jan 2014 - 19:37

for sure…

for sure!

Have you whipped one up yet?

Chop Chop :-D