Re: FB-354 drive incompatibility

Date: Fri, 22 Apr 2016 00:49:39 +0200
Message-ID: <>
Sent from mobile device. Please have understanding.

On 21 April 2016 18:36:45 CEST, "Michał Pleban" <> wrote:
> wrote:
>> Never heard what Amigas do when waiting for the disk to be inserted?
>You have to do the same ;-)
>Never had an Amiga, so I have no idea ;-)

How come? Eh, I keep forgetting that you didn't start your computing on a CBM ;-)

Well, most of the engineering that went into the Amiga is what I still after over three decades would call an excellent job. Especially when one takes into account when it was done. This particular thing though is what I refer to as "PC engineering". It reminds of the cheap and dirty workarounds used in those other systems. All the Amigas move the head back and forth when waiting for the disk to be inserted, because that's how they worked the issue around. Please note that Apple machines of the same or even earlier time don't do this BS, even if they properly react to the disk insertion. That's probably thanks to Jobs detesting crappy hardware engineering a lot. While for playing floppy based games that workaround might not be an issue because the diskette remains in the drive for most of the session, this "feature" was extremely annoying for users of HDD based systems. I know people who kept a completely unneeded diskette always in the drive just to avoid the constant, unner
clicks coming from it. 

There was however a workaround to this workaround ;-) There were software patches that made the clicking be gone, without disabling the disk insertion recognition. I never checked myself exactly how they achieved that but I /think/ they do it by changing the art and timing of the head movement signals. 

My guess is that Kickstart does it according to the rules of controlling the drive, i.e. it pulses the head in one direction, then a second or so later moves it back (or similar but still with the timing that allows the head to move and click). The patch OTOH pulses the head forward and back faster than the drive can mechanically react. Apparently this is enough to read the DSKCHNG line but the clicks are no longer there. Feel free to correct if I am wrong somewhere above. 

>Here's another idea I came up with. How about setting the motor always
>on? the the RDY line can be used as "disk inserted" because when the
>disk is ejected, the motor stops. Are there any downsides to having the
>motor always on with a diskette?

You mean other than faster mechanical wear of both the disk and the drive, extra noise and increased power consumption?  Probably not many ;-)

The obvious upside is that I would not
>need a MCU.

I guess your original assumption that a dirty cheap PIC would do the job still holds. A code for this even in asm is probably one screen of lines or less either. 

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Received on 2016-04-21 23:00:02

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