Diskette Drive Modification

Hardware questions and modifications

Diskette Drive Modification

Postby Fenyx4 » Mon Nov 23, 2020 11:00 pm

Heya!

I am continuing on the PCjr quest. I haven't been able to get the PCjr from my childhood working yet. But I have grabbed the modified diskette controller from it and have put it in a working PCjr.

After getting it all plugged in and modifying my config.sys to add /d to 'DEVICE=JRCONFIG.SYS /d2' it worked! (I haven't been able to find the boot disks we used back in the day yet. So I was glad

This mod doesn't suffer from the problem mentioned in https://www.brutman.com/PCjr/pcjr_faq.html where both drive lights come on.

I also tracked down "Home Computer Magazine, September 1984 issue" and the modification doesn't match it. And I found it interesting that the modification I have added chips to the empty chip spots on the board.

I was wondering if anyone did recognize the modification I and had some details or history on it? I wanna make sure it is documented somewhere.

Let me know if I can provide any other info or pictures.

Thanks!

https://photos.app.goo.gl/5qmWS8CcZ7aZAnkr7
https://photos.app.goo.gl/aG5boubETtydApwj7
https://photos.app.goo.gl/aG5boubETtydApwj7
Fenyx4
 
Posts: 19
Joined: Fri Sep 25, 2020 12:12 pm

Re: Diskette Drive Modification

Postby Fenyx4 » Mon Nov 23, 2020 11:45 pm

P.S. I think these are the chips that were added.

https://www.futurlec.com/74/IC7438.shtml
https://www.futurlec.com/74LS/74LS175pr.shtml

But I am by no means and expert at figuring that out so could easily be wrong.
Fenyx4
 
Posts: 19
Joined: Fri Sep 25, 2020 12:12 pm

Re: Diskette Drive Modification

Postby Fenyx4 » Sun Nov 29, 2020 10:26 pm

Weeeeell I spoke to soon. Something is borked.

When copying files to a freshly formatted diskette I get this error "cannot make directory entry". I've had it on two disks. One got about 50% full and then failed the other got about 80% full and then failed.

Googling makes it sound like this error happens when there are more than 512 files... But that definitely isn't my issue?

Anyone know what could be going wrong? Could this be caused by a drive failure? I don't see an obvious way to pop this drive open.

Or could it be a configuration problem?

Note:
I did add 'DRIVPARM=/d:1 /f:2' to my config.sys or it wouldn't format to 720.
I did try 'DEVICE=C:\DOS\DRIVER.SYS /d:1 /f:2 /h:2 /t:80 /s:9' but that was acting oddly.

Any help appreciated.
Fenyx4
 
Posts: 19
Joined: Fri Sep 25, 2020 12:12 pm


Return to PCjr Hardware

Who is online

Users browsing this forum: Google [Bot] and 1 guest