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Alley Cat Booter problems

Posted: Sun Nov 24, 2019 1:25 am
by robbo007
Hi all,
I'm trying to get Alley Cat booter working on my IBM 5160 XT. I've got a KF copy of the original booter and i've written it to a floppy with dtc. It boots fine on my IBM 5170 but not on my 5160 ??????

I've tried a cracked version and it does the same on the IBM 5160 so I don't think its due to the copy protection. It this game limited to hardware? What and I missing?

Thanks,
Rob

Re: Alley Cat Booter problems

Posted: Sun Nov 24, 2019 5:49 am
by SomeGuy
Did you perhaps write it using a 1.2mb drive and try reading it in a 360k drive? That won't work reliably. You either need to write the disk in a 360k drive, or degauss the floppy first.

Re: Alley Cat Booter problems

Posted: Sun Nov 24, 2019 9:45 am
by robbo007
Thanks for the reply as always :)
Yes, writing in a 1.2mb Drive but forcing 180k single side write. I think you did mention this before but why is it not reliable?

What do you mean by degaussing? Format the floppy as 180k fords under msdos?
Cheers,

Re: Alley Cat Booter problems

Posted: Sun Nov 24, 2019 11:14 am
by brightcaster
It's not reliable because you write it with a 96tpi head (80 track drive) and read it with a 48tpi head (40 Track drive). The narrow writing head leaves fragments of old writings (because it double steps and leaves all the odd tracks untouched) and does not erase the whole track width of 48tpi. The wider reading head gets disturbed by these artefacts!

That's why you should degauss a floppy completely before writing 48tpi formats with a 96tpi drive...

Degaussing means completely magnetically erasing the floppy with a degauser:

https://en.wikipedia.org/wiki/Degaussing

https://www.protondata.com/product/proton-1090/

David

Re: Alley Cat Booter problems

Posted: Sun Nov 24, 2019 11:45 am
by SomeGuy
Personally, I find it easier just to write low density images using a genuine 360k drive.

It is possible to convert a copy of an existing KF stream dump that was made using a 1.2mb drive by deleting the odd number tracks and renaming the remaining ones so they are consecutive. Even though the tracks were sampled at 360RPM instead of 300RPM, the Kryoflux will magically convert while writing so you don't have to do anything else.

Re: Alley Cat Booter problems

Posted: Sun Nov 24, 2019 11:47 am
by robbo007
Thanks for the details. I think it might be easier to locate a 360k drive and use that instead.