Which is better DayStar PowerCache/MicroMac Diimo

[MacSE/30]

In terms of performance which is better?

DayStar PowerCache 030 50 MHz w/ FPU (P33)? or

MicroMac Diimo 030 50 MHz w/ FPU (the one with pass through PDS)

Do they both have 64 KB cache or the size differs?

Thanks.

 

[TylerEss]

I beleive they both have 64kB cache. I think the better one is the one you can find the stuff to set up. The Diimo card is just as hard to find as the DayStar IIsi adaptor.

If you have lots of monay, I'd go with a PowerCache 50MHz (easy to find) and a TwinSpark (easy to find, expensive). Otherwise, just take what you can get.

 

[JDW]

The MicroMac DiiMO 50MHz SE/30 accelerator has the largest cache of any 50MHz 030 card for the SE-series. Yes, the Daystar cards only have 32k of cache versus 64k in the DiiMO.

Here are some photos of the DiiMO, with detailed descriptions:

Front of Card

Back of Card

Unopened Box

Box Contents

(Click on "All Sizes" in Flickr to see larger versions of the photos.)

Casting aside, for the moment, the issues of the DiiMO being "expensive" or "impossible to find," the simple fact is that the DiiMO is the best accelerator option for the SE/30 because of it's pass-thru connector on top -- and no need for a separate PDS adapter either, like you need for Daystar accelerators. Another benefit is that it is an 030 board. While slower than 040 cards, you won't have incompatibility problems like 040 cards. I found this to be true myself, as I have tested two 040 cards from Daystar in my SE/30 along with a DiiMO.

The Daystar 040 cards worked well except for some apps, but the main problem I faced was when I put in a non-stock ROM in my SE/30 (IIsi ROM for the purpose of running OS 7.6.1 and 8.1). When using the Daystar cards and the non-stock ROM, I lost the ability to read/write to 1.4MB floppies even though 400k and 800k disks worked fine. But when using the DiiMO in conjunction with a non-stock ROM, the floppy drive worked fine. Hence, there is an incompatibility with Daystar 040 cards and non-stock ROMs. I cannot say anything about Daystar 030 cards in this regard, as the one I purchased off EBAY ended up defective and I was unable to test it.

I have photos of that Daystar 030 card too:

Front of Card

Back of Card

PDS Connector PINS on Card

Solder Blobs on XTAL joints

Sad Mac Code #1

Sad Mac Code #2

 

[trag]

When using the Daystar cards and the non-stock ROM, I lost the ability to read/write to 1.4MB floppies even though 400k and 800k disks worked fine. But when using the DiiMO in conjunction with a non-stock ROM, the floppy drive worked fine. Hence, there is an incompatibility with Daystar 040 cards and non-stock ROMs.

I bet that the problem is in the firmware on the Daystar card. At a guess there's a table in there somewhere which adjusts some timing parameter related to floppy drive operations, according to which model Macintosh the upgrade is installed in. An SE/30 has a 16 MHz bus speed while a IIsi has a 20 MHz bus speed and the way Apple tended to tie the timing of floppy drive operation into stuff on the motherboard, I think it would make sense. But I'm writing off the cuff here.

However, given that the first thing to go in clock chipping experiments is floppy drive operation, it seems like this issue would also be a timing issue and the change in ROM evidence indicates it is something the Turbo 040 changes when it thinks it is in a different machine.

So, who's going to edit the ROMs to make this work? Either edit the IIsi code to report itself as an SE/30, or edit the Turbo040 firmware to use the same floppy timing on a IIsi as it would on an SE/30...

 

[JDW]

Trag, I have zero doubts about it. It is truly a ROM code issue. The issue could be fixed by someone who knows how to edit the ROM, but I am not that man. Indeed, I doubt anyone other than an X-Daystar engineer could do the job right.

I've also tried two different boards and 3 different ROM versions (I had the ROM updated in one of my boards to the latest version -- a guy here in Japan does that for a fee). None of those resulted in a working 1.4MB floppy when a non-stock ROM was in there. I mention this only to say that no Daystar ROM that I know of will make the Turbo 040 properly handle 1.4MB floppies when used along side a non-stock ROM. Hence the need to fix the ROM code.