[Coco] Disk Drive FD 501 Floppy

[Robert Gault]

You will need to patch boot_1773.asm and generate a new track34 or use dEd to change the boot module 
in track34 on a bootable disk.
The last byte in Boot is the drive from which OS9Boot should be loaded. By default this is drive#0 
and the byte is $01. To change it to drive#1 the value should be $02.

If you use dEd with nos96809l2v030209coco3_40d_1.os9, you would go to sector $266 and you would see 
a series of $39 then $FF $40 $01. Change the $01 to $02 to boot from drive#1.
Your boot module won't have the correct CRC but it probably will still work.

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The variable resistor most likely controls the drive RPM. There should be a strobe pattern on the 
flywheel which should look stationary at the correct spin speed. You could also run a program to 
measure the drive speed while adjusting the variable resistor as needed.

Robert

Melanie and John Mark Mobley wrote:
> I bought some super tech (TM) multi-duty complex hi temp applications (red)
> grease for Walmart.
> I put the grease on the rods that hold the read head and let the read head
> slide back and forth.
> This did not fix the issue.
> I swapped drive 0 for drive 1.  I swapped the termination resistor pack.  I
> swapped 3 jumpers on each drive.  And now drive 0 will boot OS9 without a
> warm up time.
> There is one variable resistor on the drive, but I do not know what it does
> or how to adjust it.
> I do not now know how to test dive 1 as I can only boot from drive 0.  DOS 1
> starts booting from dive 1 but then switches to drive 0.  Perhaps I need a
> different boot disk.
>
> -John Mark Mobley
>
>
>