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Microchannel IDE controller

eeguru said:
I didn't think of PC/104. But you are supposed to be discouraging me from more rabbit holes and testing XT-IDE instead! Fail. :)
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Heh, indeed :)

eeguru said:
But NICs and even serial cards are still relatively available for MCA on eBay.
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Yeah, the thought about multiple PC/104 modules on a single carrier was more to deal with lack of expansion slots in some systems -- portables, all-in-ones like the PS/2 Model 25, et c. Part of the reason I hadn't seriously looked into doing a MCA board (of any type) was due to the continued availability of MCA SCSI boards and cheap SCA drives -- though that's a temporary solution, as eventually the MCA SCSI boards will become scarce, and AFAIK no one is actually producing SCA drives anymore (though there's a massive heap of NOS surplus out there).
 
eeguru said:
The biggest problem with a homebrew MCA design is sourcing appropriate back plate connectors - which is a hard enough task for ISA.
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The back plate could be made out of PCB. I think the thumbscrew opens enough to make this workable. That way when the main PCB is made, it's just an extra bit of circuit board.

I would be interested in an MCA-to-ISA bridge project. Would the ISA run at 10MHz? I find this sort of thing fascinating. It is beyond my own capabilities, but if I can help I will.
 
I don't really have time to start a new project like an ISA bridge. My main point was after a lot of research my message is don't be scared of Micro Channel. I consider some of the design choices of MCA pretty bone-headed mistakes. I think IBM was just trying to make things sufficiently different from ISA to warrant new patents and licenses. MCA is designed to work with 286 systems and the standard signals coming out of an early x86 cache-less burst-less asynchronous only BIU. There isn't much to 'enhance' with a bus architecture. Smoke and mirrors marketing at it's best...

The National app note I pointed out above was really helpful in fully understanding the practical points of MCA design. And if you ignore the DMA sections of it and the corresponding schematic, the meat reduces to a thin piece of bacon.
 
eeguru said:
don't be scared of Micro Channel
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Don't fear the reaper...

Some microchannel machines may outlive us all. Look at the XT-IDE... True, it is used on an ISA based system, Far more primitive than SCSI, yet folks still developed for it.

Something that will always impress me is how the pioneers designing microchannel did it all with simple logic chips and 32k EPROMs....

A design imperative for microchannel was that programs designed for ISA systems could be used on microchannel. Drivers are a different thing, but MCA emulated an ISA system....

So what is wrong about an IDE controller for MCA? Plenty of MCA DBA-ESDI systems that could use something a bit bigger than 160MB... Or 80MB...
 
eeguru said:
It's a simple stamping with 3 bends - 1 of them in an opposing direction. Anyone have an idea on where to go to get quotes for such a thing? On-line preferably due to economies of scale and long term sourcing. The blue plastic tabs and card extensions can just be 3D printed.
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These guys used to make MCA brackets, including the plastic bits, back in the day, they are local to me!

http://www.globebrackets.com/

Look on your MCA cards, chances are high that Globe made the bracket.
 
I have zero skills to offer in the making of a circuit and board for this. But I would almost certainly buy and use an MCA IDE controller. SCSI can be had in MCA pretty easily, but SCSI drives are not as easy to come by as IDE ones, and then if you add in a SATA to IDE adapter, now you could use HDDs that were made now, not just ones that were made 20+ years ago.

And that's my $0.02 on this topic.
 
An MCA 68 pin LVD card would be nice. For the old OS you are going to be running on a vintage MCA machines SATA is overkill.
 
You mean RS/6000 MCA cards that don't work in PS/2 machines? There is the corvette card for the PS/2 line with the funky connector (have that).
 
Unknown_K said:
You mean RS/6000 MCA cards that don't work in PS/2 machines? There is the corvette card for the PS/2 line with the funky connector (have that).
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Does this card not work in a PS/2?

http://www.ebay.com/itm/IBM-11H3600...657545&hash=item1a22b4073a:g:~uMAAOSwt5hYZA7R

Also many wide LVDS devices will work in (and auto detect) narrow SE mode. And at least there is a decent SD card solution for narrow SCSI. I get 950 KB/s in Norton SI using a Future Domain narrow SCSI controller paired with a v5 SCSI2SD in a Tandy 5K. Which is faster than any period correct drive.
 
eeguru said:
Does this card not work in a PS/2?
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Oops, got distracted by another card, yes, the Corvette does work in PS/2s -AND- AIX.

SE -ONLY- on both the interior and external SCSI controllers. You can use LVD drives that are jumpered to force SE mode...
 
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eeguru said:
There are lots of wide SCSI MCA cards on eBay with 68-pin LVDS connectors that are bootable.
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What we have here is gender identity confusion.

Though one could consider the 68 pin internal port on a Corvette as one used by LVD, there are only high voltage SE and Differential SCSI controllers for microchannel. LVD was a dream at this point. One good thing is that many LVD drives can be jumpered to force SE mode.

IIRC, only the 68 pin versions can be forced to use SE mode. Again, IIRC, forcing SE drops the transfer down to Fast/Wide rate of 20MB/s...
 
Chuckster_in_Jax said:
The "Corvette" is a 32 bit MCA card. Don;t forget that many of the PS/2 computers only have 16-bit expansion slots.
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That is not the worst of it, the 8580 (and 70, IIRC) BIOS is incompatible with the Corvette. They tried updating SC.EXE and it still bombed.

Not that it matters, but perhaps a Corvette would work in a 8556 in a 16 bit slot, but it would be slower.
 
Unknown_K said:
An MCA 68 pin LVD card would be nice. For the old OS you are going to be running on a vintage MCA machines SATA is overkill.
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Well my point with the SATA there is that you can plug a SATA drive into an IDE controller, which means the pool of available new drives goes up immensely and even opens up the realm of using new low end SSDs. Performance wise, you are correct, this would be overkill, but it's better to overkill the storage than have none, or have to rely on 30+ year old spinning SCSI drives.
 
Would really be awesome to see a MCA to IDE card made, as my P70's hard drive (120mb) certainly won't last forever and it would be nice to use a CF card in it and be able to hit 2gb in partition sizes like my Eduquest Model Fifty has to go with its DX4-100 CPU. I would certainly buy one for both my P70 as well as my desktop model 70 that has a dead floppy drive since i can no longer install anything on to it. While a MCA version might not sell as many as XT-IDE ones do they would still definitely be snatched up quick by any collector with MCA machines.
 
If you are going through the effort, SATA. 100%.

Also, I'd rather see a new sound card come out. But that's just me.
 
luckybob said:
Also, I'd rather see a new sound card come out. But that's just me.
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Yes! That would be awesome! I’d love to have a SB compatible sound card in my Model 80, without having to pay insane prices for an MCA Sound Blaster. I have never seen one for sale, but I can only imagine the bid-war chaos it would be if one of those showed up on eBay.
 
There are many regular OEM PCs that match/exceed PS/2 performance. So there is no compelling reason to invest in MCA PCB development. Very small PS/2 audience out there anyway.
 
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