Need help integration of FDC with TEAC FD-55GFR

[Dieter Schneider]

Hi all, 

I need your help how to integrate FDC with FD-55GFR.

When connected via Serial to FDC I can read out drive information.

Firmware (MITS) is always telling me, please insert disk - but disk in inserted - maybe somehting in wrong in jumper configuration on floppy drive?! 

Could somebody help me please :)

BR
Dieter

[da...@hansels.net]

Are you able to write and read a disk from within the monitor ("w" and "r" commands)?

[Dieter Schneider]

Hi David,

maybe I am doing somehting wrong with the command line syntax, but while entering the "r" command I receive the same "please insert disk,..."

Is the syntax of the "r" command correct?

There is  a led, close to the insert slot of the drive - that led is never ever on.

Is that a bad sign?

BR
Dieter

[da...@hansels.net]

It sounds like the controller is not able to control the drive at all. If you type "m 1", does

the drive motor start spinning?

Try accessing the drive as drive "1" (instead of the default 0) by issuing a "d 1" command
in the monitor before trying the motor and/or read/write commands.

[Dieter Schneider]

HI David,

when accessing d 1 and entering m 1, the motor starts spinning but still with the message "please insert disk..."

My floppy disk is empty and hopfefully the type of disk are supported:

BR
Dieter

[da...@hansels.net]

The disk should be fine, the only requirement is that it's a HD (1.2MB) disk.

Does the light on the front of the drive come on when you type "d 1"? It should.
If it doesn't, one explanation would be that the "drive select" jumpers ("straps")
are not set to their default position (D1 on, D0, D2, D3 off). There's a description
of the straps and their locations in the drive user's guide (page 131-134):

https://github.com/dhansel/Altair8800-IOBus/blob/main/04-disk-controller/doc/TEAC%20FD-55GFR.pdf

You should also confirm that the other straps are in their default position.

Page 101 of the user's guide says that D1, U1, DC2, II and FG should be
inserted, all others should be removed.

David

[Dieter Schneider]

Hi David,

I was able to fix the strap (jumper) on U1 and D1.

FG (yellow marked) was already set,

So all mounted jumpers are yellow highlighted on the screenshot below.

Then also the red Led turn on, when selecting drive 1 via "d 1" which sound in first instance good :)

But somehow I am not able to find the right straps (jumper position) for DC2 and II

Are you able to tell me where they are on my drive?

Maybe you could give me a hint or draw the position on my photo from the PCB of the floppy drive

BR
Dieter

[da...@hansels.net]

Sorry I'm not an expert on these drives, I only know the one I have and that

looks different than yours. Apparently there were a number of different versions.

Are you still getting the "please insert disk" message? The DC2 and II straps should
not prevent the controller from seeing/reading the disk. The DC2 strap may become important
later (detecting whether a disk that was already inserted had been taken out and
replaces with a new one). The II strap is about rotation speed which may become
important if you want to work with DD disks (for 88-MDS emulation) but should not
matter for now.

[Dieter Schneider]

Yes I still get this message  "please insert disk"  while DC2 an II is not set 

😢

Are there any other possibilities what I could try? 

Sent from my iPhone

---

Von: altair...@googlegroups.com <altair...@googlegroups.com> im Auftrag von da...@hansels.net <da...@hansels.net>
Gesendet: Monday, May 8, 2023 10:25:52 PM
An: Altair-Duino <altair...@googlegroups.com>
Betreff: Re: Need help integration of FDC with TEAC FD-55GFR

 

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[da...@hansels.net]

The controller is showing the message because it is not seeing any activity
on the "INDEX" line of the drive while the motor is on. The INDEX signal should

go low for a short time 6 times per second as the disk's index hole passes the

detector in the drive.

Either the disk drive is not producing this HIGH-LOW-HIGH sequence for some
reason or there is a problem that prevents the controller from seeing the signal.

If you look at the controller schematics:

https://github.com/dhansel/Altair8800-IOBus/blob/main/04-disk-controller/schematic.pdf

you can see that the INDEX signal is connected to pin 19 of the ATMega328P processor.

You could try and measure whether there's connectivity between pin 19 of the ATMega and

wherever the signal (pin 8 on the floppy disk cable) connects on the drive PCB. That way
you could exclude a faulty cable.

David

[da...@hansels.net]

Yes! The disk is inserted upside-down and that will definitely prevent the disk drive

from seeing the index hole and produce exactly the behavior he is seeing. Good catch!

I did not notice this in the picture.

[Tom Lake]

The diskette looks upside down to me. On a TEAC, the label should be away from the arc with the arrowheads on it. It should be on the same side as the lever.

On Monday, May 8, 2023 at 3:06:13 PM UTC-4 dieter.sc...@gmail.com wrote:

[Dieter Schneider]

omg :-o

such a stupid mistake :-D

I flipped the floppy and now I can access drive speed and drive information.

next days I am gonna integrate the drive into my AD :) 

keeping fingers crossed that it will work as well :)

Thx you David and Tom for your support.

And btw, David you are a brilliant engineer! 

BR
Dieter