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Heads up: Compaticard I on eBay

dpatten said:
What is the lead count on the QFPs?
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Typically a multi-IO chip will be QFP-100 or some variant. These are fairly mid-sized chips. It is not an issue for making the PCB though only its assembly since that would require SMT soldering. However even soldering a QFP-100 isn't that hard to do. There will be push back though.

Thanks and have a nice day!

Andrew Lynch
 
Chuck(G) said:
Since we'll be operating in PC-AT mode, you need only pull IDENT high. You can leave MFM NC as that pin has an internal pullup. Since we're not creating a microchannel board, PS/2 mode is irrelevant.

The CC IV has some added logic (and external buffers) for support of 8" drives; for example, being able to assert reduced write current, but there external adapters for that (e.g. FDADAP), so that's not important. There's also logic to allow for several I/O addresses, selectable DMA and IRQ, but again, that's just icing on the cake and not strictly necessary. I seem to remember that the CC IV uses 3 20-pin GALs for its random logic. I'm guessing that you don't want to get into the GAL programming business... ;)

Thanks,
Chuck
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OK, I will spin up a prototype schematic and PCB layout and send them to you for review. You can mark it up as you see fit and let me know the changes and/or corrections. As it stands right now I see an XT-IDE sized board with a fairly loose set of chips on it. Once we get that done then we can look into adding additional features. Do you know the GAL equations for the CCIV or at least what they are doing? I have a CCIV too but it is buried in my pile of *stuff* in the workshop.

I thought 8272 supported TG43 "out of the box". Doesn't the PC8477B?

Thanks and have a nice day!

Andrew Lynch
 
lynchaj said:
I thought 8272 supported TG43 "out of the box". Doesn't the PC8477B?
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No--TG43/RWC was already becoming an artifact of 8" drives when the 765 came out. Later 8"drives don't use the signal--they derive it internally. And it just doesn't exist on 5¼" and 3½" drives at all. Thankfully, all of the precomp logic is internal to the 8277, so you don't have to worry about "inner track" issues there.

--Chuck
 
Chuck(G) said:
Edit The part number for the 48 pin DIP version of the 8473 is DP8473AN; the number for the 44 pin PLCC is DP8473AV. The PLCC version supports only 2 drives, rather than 4. The 8477 part number is PC8477 and also includes support for 1Mbps (2.88M format) data rate and comes in a 68 pin PLCC. There's a seller on eBay offering a lot of 20 for about $40. He says that he's got more than 10 lots of 20 available.
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So is the plan to spin up a schematic using the DIP or PLCC versions of these chips?
 
Yes. I prefer the 8473 as it has the unique ability to read and write 128-byte MFM sectors. But the 8477 is in better supply and, if you don't care about FM capabilities, pin-compatible with the Intel i82077, so from a logistics standpoint, a better choice.
 
Hi

Well good news! We have a schematic and PCB layout. That's the easy part! It is being reviewed presently and hopefully firming up soon. If you would like to review the schematic and PCB layout please contact me. The more experienced eyes and minds on this project the better!

Next is the hard part... organizing the prototype board build and test. This is usually where community project ideas fade away and die.

I can get four (4) prototype boards from www.33each.com for $150. Say $160 with shipping for easy math so that's $40 per prototype board. We need both builders and sponsors. They can be the same persons or they can be different. For example a sponsor could buy a board for a builder for build and test etc. We have to get past this stage for a viable XT-FDC project.

View attachment 10134

If there is truly a need for a community 8 bit ISA floppy drive controller then people will come forward. Hopefully we can recapture some of that XT-IDE "lightning in a bottle"

Please consider. Thanks and have a nice day!

Andrew Lynch
 
Hi

Thanks! The PCB uses the same planform as XT-IDE and is just a bit too big for 10x15 cm. Honestly, I've been having prototype boards made with Advanced Circuits (4PCB and 33each) for quite some time now and would prefer to continue with them. They are a top notch prototype board house. The very highest quality at a reasonable price. We really only need a small number of prototype PCBs and I think 4 should be sufficient. You are right that gold fingers are not necessary for prototype boards since they are short lived temporary units.

Thanks and have a nice day!

Andrew Lynch
 
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