C1P-OS65D_3.3 - Head Step Time too short for older 5-1/4" Floppy drives

[blkrckz28]

I have a Siemens FDD100-5 Disk Drive I am attempting to get to work with a C1P+610 system.
The specs on this drive specify a minimum head step time of 25ms.

Using the DiskTest5.HFE image/test, I can successfully perform all disk tests with success.
I have also successfully used the GreaseWeasle to write/read and verify images with this drive, and confirmed that I need to set the GreaseWeasle step time to 20ms (or longer) for use with this drive.

After booting into C1P-OS65D_3.3 using the C1P-OS65D_3.3_Tutorial5 disk with a my GoTek, I am trying to perform a disk copy from the C1P-OS65D_3.3_Tutorial5.HFE disk image (GoTek) to my Siemens FDD100-5 floppy drive.
However, the head stepping of the Siemens doesn't move and just seems to 'jitter' indicating that the step period is too short for this drive.

Scoping the STEP signal when running the DiskTest5, the STEP signal period is 40.8ms. Plenty slow enough for this drive.
However, The STEP signal when using the OS65D_3.3_Tutorial5 disk is 8.2ms, which is way too fast for this drive.

Question: In the OS65D_3.3 memory space, where would be the memory parameter for the STEP settling time?

P.S. I have tried this setup with a newer 5 1/4" half height high density drive and it works flawlessly.
I would love to get this system to work with an older full-height floppy but also realize that I may have to investigate getting a better performing full-height drive instead of modifying the OS65D_3.3 image...

Thanks in advance,
Andy

[HOWARDHB]

Hi Andy.

I had the same issue with my Shugart SA400 full height 5¼" drive (35 tracks) in that it could not step reliably when booting OS65 on my Klyball C1P / 610 / D13v2.
It workef fine with the Greaseweasel though.

Danny made a single track disk image that booted reliably, proving that the 610 and data separator were not the problem.
(zip attached)

I eventually replaced the SA400 with an MPI 51, 5¼" full height drive and my machine has worked flawlessly since.

Note: I have a strange "quirk" with my machine in that when copying flopy disks (using the copy function on Tutorial disk 5), either from Gotek to disk, or disk to disk, the two drives must be addressed as "A" and "D", using a straight cable.


Mark Csele documented the step timing issue with the Sugart SA400 on his web page, and describes his "fix" for Hexdos. ( by modifying the boot sector )

scroll down to near the bottom of the page to the paragraph:
Diagnostics of the Floppy Disk System

www.markcsele.ca/hobbies/my-vintage-com ... rboard-ii/

tzonly.zip

(101.06 KiB) Downloaded 28 times

[blkrckz28]

Thanks for the reply...
I am re-thinking the whole 5 1/4" full height thing.
Maybe if I can find a half height 720K or even a 3 1/2 " instead with my gotek. Lower profile for an enclosure, etc.

It would just look so cool with the retro full-height though and I have a drive enclosure that will work...

Andy

[Thomas]

Hi Andy,
I'm not that expert on OS65D but for the OS65D 3.3 , you can find in the source listing the relevant sections for the step rate.

L2678 LDX #$C ; 12 MS
change with POKE9849,40

L26A2 LDX #8 ; 8 MS
change with POKE 9891,40

to get a 40ms step rate.
After booting the OS65D tutorial disk, press 9 to enter the OS-65 sytem and apply the above Poke commands and continue with run.
Not sure if it will work, but its easy to give it a try.
To permanently change the step rate, you must modify the disk image file for the Gotek accordingly.

Thomas

[blkrckz28]

Freek'n brilliant!!!

That works...

Thanks for the info Thomas....

BTW: Where can I get the source files for C1P-OS65D ?


Andy

[Thomas]

Great !

If Marks site is up an running, check here osi.marks-lab.com/reference/reference.htm for the source code.

Thomas