Carrera040 cloning

[nottomhanks]

Does this card work with the Micron or Pivot cards?  Very exciting!!

 

[TimHD]

After some back and forth it turned out that not all combinations of CPU and cachecard will run at 40MHz.

I swapped around different CPUs and even found a combination where the original cachecard would refuse to work resulting in a hard crash once the Carrera INIT loads.

I will be revising the PCB design a little and then post the gerbers and a BOM so everyone can build their own cachecards.

Is there a matrix of what works/doesn’t, or had the issue been resolved?

 

[Bolle]

Is there a matrix of what works/doesn’t, or had the issue been resolved?

I think this was related to one of the CPUs actually being a 25MHz chip. All my 33MHz and 40MHz parts would work just fine.

That one 25MHz chip would work ok at 40MHz without the cache module but would fail once the cache came into the game.

 

[nickpunt]

Looks great @Bolle! Consider me interested  Have you tried overclocking at all? I imagine most of the later CPUs can hit 50mhz easily, not sure about the accelerator chips or whatever effects it may have on the bus. The Daystars can hit 48mhz.

 

[TimHD]

Ditto. Certainly for a cache module. Would also help underwrite by committing to getting one or two more complete sets for other Macs of mine. 

I assume you'd just supply the board (or someone else here who does this) and we'd need to source CPUs?

 

[Bolle]

I assume you'd just supply the board (or someone else here who does this) and we'd need to source CPUs?

 Most probably, yes. Sourcing the out of production stuff that's on there is painful enough already, so I'll avoid to add the trouble of finding non-fake CPUs on top of that.

Have you tried overclocking at all?

Not yet, the clock generator for the 040 probably is one of the limiting factors here - the same part is used on the Turbo040 and the Carrera040:



I am using a MC88916DW80 which is rated at  a maximum of 40/80MHz for the B- and P-clock respectively.

The exact same clock generator (although at a lower speed rating) is also found on some Macintosh logicboards.

I have seen Turbo040s with 35/70MHz and lower 25/50MHz rating as well. All Carreras I have seen so far have used the 40/80MHz version.

 

[TimHD]

Speaking of which, is there an authoritative guide to finding legit CPUs - esp the 68040 non-LC 40mhz ones? Did I see once that they no longer make them hence it’s about finding old ones and avoiding fakes/screen printed variants that are slower or actually LC chipsets?

 

[Kai Robinson]

@TimHD I use UTSource - plenty of L88M mask Freescale 040's there for about $59 each. 

 

[Solvalou]

Oh that's very, VERY nice Bolle. you always find ways to out-do yourself with yet another amazing example to reverse engineering. I don't know how you do it!

Definitely still up for a Cache add-on for my Carrera that's sitting in my IIci.

To be honest, money-no-object, I'd really love another complete set to put in my IIvx, but really that would probably be a bit wasted in that and would be nothing more then morbid fun to see the lackluster results.

 

[demik]

Very nice ! 

How does this fit an Iicx ? Do you need another extra board ?

 

[jessenator]

How does this fit an Iicx ? Do you need another extra board ?

This post shows the MicroMac IIcx adapter for the Carrera  Might be a bit of unobtanium these days...

 

[demik]

Thanks ! Looks only simple traces to create a PDS slot.

Should be straightforward to replicate

 

[pcamen]

This post shows the MicroMac IIcx adapter for the Carrera  Might be a bit of unobtanium these days...

I gave away two of them a month or two ago.

 

[trag]

I am using a MC88916DW80 which is rated at  a maximum of 40/80MHz for the B- and P-clock respectively.

The exact same clock generator (although at a lower speed rating) is also found on some Macintosh logicboards.

I have seen Turbo040s with 35/70MHz and lower 25/50MHz rating as well. All Carreras I have seen so far have used the 40/80MHz version.

Well, if you find a use for the slower ones, I have a reel of 998 of the MC88916DW55...

 

[Kai Robinson]

Those are available at https://www.utsource.net/sch/MC88916DW80.html - £2.49 a piece or £2.12 a piece if you buy 10 or more...

 

[Frobozz]

Amazingly cool. 

 

[Bolle]

Thanks ! Looks only simple traces to create a PDS slot.

Should be straightforward to replicate

I can provide the schematics of the Micromac IIcx adapter if you want. Got one of those as well.

Also mind you will need the more uncommon socketed IIcx logicboard unless you are ready to desolder the CPU on your logicboard and put a socket in place.

 

[demik]

I can provide the schematics of the Micromac IIcx adapter if you want. Got one of those as well.

Also mind you will need the more uncommon socketed IIcx logicboard unless you are ready to desolder the CPU on your logicboard and put a socket in place.

Thanks ! I got two IIcx, one socketed, one soldered. The socketed one isn't starting yet (recap done), Don't want to mess with the working one, I will keep your offer in mind.

Good job anyway !

 

[Bolle]

Also for bragging rights:



No external cache though at that speed, so you're still slower than a 40MHz 040 with 128k external cache.

Benchmark speed of the cacheless 50MHz 040 in a SE/30 is in the range of a 50MHz 030 with external cache.

 

[Solvalou]

Now that's a fast SE/30!  8-o

Can we see some Speedometer readings?