Franklin Ace Floppy controller IC

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Franklin Ace Floppy controller IC

Hi, I'm looking for the floppy controller IC to repair my Franklin Ace.  I've narrowed it down to it being the reason my floppies don't work correctly... they read just fine, but they won't write.  The drives work, I can tell because if I plug them into a Disk ][ controller, they work great.

 

The IC I'm looking for is a USI chip, I think the part # is 4003000

 

If anyone has one from an old machine, please let me know.  Thanks!

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Wasn't that a custom chip

Wasn't that a custom chip specifically for that computer?  Perhaps an FPGA?

You'll probably not find one in the wild if that's the case, unless it was pulled from another dead Franklin.

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baldrick wrote:Wasn't that a
baldrick wrote:

Wasn't that a custom chip specifically for that computer?  Perhaps an FPGA?

You'll probably not find one in the wild if that's the case, unless it was pulled from another dead Franklin.

 

Yup, that's the one.  Looks to be custom.  The write gate pin just stays high, so it thinks it's writing but it isn't.  

I figured if there's any place online where I could find this chip, it'd be here.  If anyone has one from a Franklin, or knows what this chip is composed of, I'd really appreciate it.

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mnaaron wrote:baldrick wrote
mnaaron wrote:
baldrick wrote:

Wasn't that a custom chip specifically for that computer?  Perhaps an FPGA?

You'll probably not find one in the wild if that's the case, unless it was pulled from another dead Franklin.

 

Yup, that's the one.  Looks to be custom.  The write gate pin just stays high, so it thinks it's writing but it is

Mine, on a virgin machine that had sat untouched for decades, decided to die after only a few power on cycles. I'm thinking of cutting its traces and properly wiring slot 6, as there is no schematic for the FDC, and it could just be supplanted with a normal Disk ][ card, except that it interferes with slot 6, hence the little plastic plug that is normally in that slot. 

 

It replaces the two PROMs on the Disk ][ controller, so it isn't anything magical, but there is no documentation for it at all. 

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Timelord wrote:mnaaron wrote
Timelord wrote:
mnaaron wrote:
baldrick wrote:

Wasn't that a custom chip specifically for that computer?  Perhaps an FPGA?

You'll probably not find one in the wild if that's the case, unless it was pulled from another dead Franklin.

 

Yup, that's the one.  Looks to be custom.  The write gate pin just stay

 

Do you have an Ace 2000 series?  if so, I  have the technical reference manual for it, with full schematics (although it's missing the page for the ROM decoding).  I should scan it, it has the schematics for the disk controller circuitry which uses that chip, and I'm assuming it must be pretty close to the same on other Ace series computers if they use the same chip.

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mnaaron wrote:Timelord wrote
mnaaron wrote:
Timelord wrote:
mnaaron wrote:
baldrick wrote:

Wasn't that a custom chip specifically for that computer?  Perhaps an FPGA?

You'll probably not find one in the wild if that's the case, unless it was pulled from another dead Franklin.

 

Yup, that's the one.  Looks to b

 

Ace 1200 here. I have the service manual, and it does not give schematics or practical/useful docs for the IC itself, short of swapping it. 

 

I would not however turn my nose up on the scan, but I'd put it up on Asimov or here on Fritter for everyone to access. 

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I just scanned the FDD

I just scanned the FDD controller page.  I plan on scanning the entire manual soon.  Maybe it's helpful?

 

https://drive.google.com/file/d/10dYeREKXB4niEQOeMoGy3sej9IbegIsk/view?usp=sharing

 

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Franklin Ace FD Controller available on ebay.

I see that a Franklin Ace floppy disk controller card is listed now on ebay for $29.95 with free shipping. Might be an easier route to go:

 

https://www.ebay.com/itm/Franklin-Ace-Computer-Floppy-Disk-Drive-Controller-Card-/184245822508

 

 

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The problem is, on the Ace

The problem is, on the Ace 2000 series, the slot 6 disk controller is integrated into the motherboard.  And, that controller card has an EPROM and not the custom IC.

 

BUT!  I managed to get it working!  On my FDC IC, the write gate wasn't pulsing on writes... so I stole the write signal from the latch, put it through a transistor and sent it out to the write gate on the drives (after clipping the lead of the output driver).  Works great now!

 

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Also, looking at the

Also, looking at the schematic I posted above, it looks like that custom IC is just the state machine.  It only takes the C0Ex signal.  If you look at the bottom of the schematic, C6xx goes somewhere else (I'll have to look) to the C6&C8 signal.  I am curious why that chip needs 2mhz and 7mhz signals though.

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