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D Bit FDADAP boards

bolex

Experienced Member
Joined
Feb 6, 2021
Messages
429
Location
Utah
I'm looking to buy a pair of FDADAP boards. Let me know if you have one (or 2) you can spare.
 
As far as I know, John WIlson's still making these. What these provide for 8" drives is primarily the TG43/RWC signal. Many later 8" drives automatically supply this, so you can get by with a simple cable (34-to-50) adapter rather than the Dbit thingie.
 
I've been emailing Dbit since January requesting them. I'm just not getting a response. I've just chalked it up to pandemic and supply chain problems that just about everyone is having. I have a pair old full-height Shugart SA-851's that I'd like to use to write disks with that would need the exterrnal TG43 signal. They seem to read disks fine. I'm currently writing with a Tandon 848-02 Model II that does have a jumper for internal handling of the TG42. I really just want to have a couple of these on hand just in case.
 
I've been emailing Dbit since January requesting them. I'm just not getting a response. I've just chalked it up to pandemic and supply chain problems that just about everyone is having. I have a pair old full-height Shugart SA-851's that I'd like to use to write disks with that would need the exterrnal TG43 signal. They seem to read disks fine. I'm currently writing with a Tandon 848-02 Model II that does have a jumper for internal handling of the TG42. I really just want to have a couple of these on hand just in case.

If your main concern is writing disk images, IMD has a feature where it can drive the TG43 signal out the parallel port
 
For deriving the TG43 signal, would an open-source version be useful? I'm not much on PCB layout, but I'd be happy to do the firmware and circuit design. It's not rocket science. FWIW, MicroSolutions had a simple 34-pin in/50 pin out header board that they used in their adapter for the CC IV. No magical MCU involved.
 
Let's gauge interest in this. If there's enough, then I'll start getting specs together and we can go from there. I a;so have the MS adapter boards, which can also serve as a layout guide.
 
TG43 on the sa85x is unusual, it lowers the write current AND it changes the characteristics of the read differentiator.
They removed that on the 860 and have circuitry to lower the current at track 40

i wonder if on the 85x if this was intended only for double-density applications.
 
I emailed John earlier in the year with no response. I tried again in late August and he was making adapters again. I received mine in less that two weeks from payment. That being said Chuck I would be interested in the project.
 
I went to my PayPal account and the date of purchase was July 23rd. Not August. Sorry my memory is not that good. I did email John several times with no reply, even talked to him once on the phone as he assured me he intended to keep making the adapters.

unless you fine another alternative I would email him every month or so. I tried some of the other adapters off eBay and din not have any luck,

Maybe there will be enough interest for Chuck to design a PCB.
 
I just received an email from John and he now says he has 53 FDADAPs in stock. I've ordered 2.
 
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