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Author Topic: A4000T funky floppy cable  (Read 2079 times)

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Offline J-GoldenTopic starter

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A4000T funky floppy cable
« on: January 17, 2004, 02:52:02 AM »
ok ok, I've worked on Amigas for quite a while now but have never seen a hack like this.  The A4000T I got was having intermitant floppy probs, so I opened and lo and behold, the floppy cable was hacked all over.  

The second to last pins of the cable on either side were crossed over each other and going into each others port on the connector

help?!?!?!?!
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Offline Castellen

Re: A4000T funky floppy cable
« Reply #1 on: January 17, 2004, 03:45:13 AM »
Mine is the same, I think they came from the Amiga Technologys factory like that so they could use standard Sony PC floppy drives, which is what you'll probably have.

Wires 2 and 34 are crossed over in order to put the ready and diskchange signals onto the correct pins of the drive.


If you suspect your cable is intermittent, just make another one exactly the same, or otherwise get a proper Amiga drive and use a standard 34 way ribbon cable.


While on the subject, A4000T users will know that the motherboard SCSI and IDE controllers use 2nd.scsi.device and scsi.device
On mine, scsi.device is for the IDE controller, and 2nd.scsi.device is the SCSI controller.  Are they ALWAYS like that, or do they change over on some machines/setups??
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Offline kgrach

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Re: A4000T funky floppy cable
« Reply #2 on: January 17, 2004, 08:24:44 AM »
Believe it or not all the early PC's had the same cable.
The Amigas are actually correct it is the PC's that have it backwords.
The Amiga disk drive port is compatible with the Shugart standard. IBM screwed up when they made the PC and mixed up the two lines.  

Since all early PC's were exact clones of the IBM They all had the same problem. So all early PCs had the same stupid twist in the cable. Later drive manufacturers added a jumper on the drive that would swap the pins so the twist became unnecessary. So all you had to do to make a drive Amiga or PC compatable was to move a jumper. In a cost cutting move disk drive manufacturers have since removed the swap line feature and the diskready line. Since PC's don't use them.

Kurt
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Offline Jope

Re: A4000T funky floppy cable
« Reply #3 on: January 17, 2004, 08:53:11 AM »
Quote
Believe it or not all the early PC's had the same cable.


Hmm, are you sure about this?

All the PC floppy cables I've ever seen only twist the DS and MC lines to the last connectors. Never a 2 <-> 32 swap on PCs...
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Offline Framiga

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Re: A4000T funky floppy cable
« Reply #4 on: January 17, 2004, 09:34:54 AM »
Hi Jope

i agree . . .they "seems" the same but aren't.

Pay attention, to play with floppy drive connection!!!

Ciao

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Offline PaSha

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Re: A4000T funky floppy cable
« Reply #5 on: January 17, 2004, 11:16:43 AM »
Quote

While on the subject, A4000T users will know that the motherboard SCSI and IDE controllers use 2nd.scsi.device and scsi.device
On mine, scsi.device is for the IDE controller, and 2nd.scsi.device is the SCSI controller.  Are they ALWAYS like that, or do they change over on some machines/setups??


No, they are not always like that. I don't use IDE at all, so my SCSI is scsi.device, on the IDE I have a self-made 'terminator' to avoid the waiting time.
IIRC the controller with the drive with the highest boot priority gets scsi.device or something like that.
Anyways, I remeber reading about it somewhere on the net, do a search and you should find something.
Also, when I was using a A4000 D with a A4091 controller, the A4091 was scsi.device since i didn't use any IDE drives.

-Paul
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Offline patrik

Re: A4000T funky floppy cable
« Reply #6 on: January 17, 2004, 11:34:55 AM »
@PaSha:

How do you build that "ide-terminator"?


/Patrik
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Offline PaSha

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Re: A4000T funky floppy cable
« Reply #7 on: January 17, 2004, 12:03:03 PM »
Have a look at http://aminet.back2roots.org/pub/aminet/hard/hack/IDE_Killer.lha

Two 4.7 kOhm resistors from pin 39 to pins 3 and 5 respectively. This somehow makes the IDE controller immediately understand that there is nothing there.

-Paul
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Offline patrik

Re: A4000T funky floppy cable
« Reply #8 on: January 17, 2004, 01:49:17 PM »
@PaSha:

Cheers! :)


/Patrik
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Offline J-GoldenTopic starter

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Re: A4000T funky floppy cable
« Reply #9 on: January 17, 2004, 02:10:29 PM »
Quote

PaSha wrote:
Have a look at http://aminet.back2roots.org/pub/aminet/hard/hack/IDE_Killer.lha

Two 4.7 kOhm resistors from pin 39 to pins 3 and 5 respectively. This somehow makes the IDE controller immediately understand that there is nothing there.

-Paul


wow!  that's rather cool!  thankz for the info since I don't use my IDE at all......
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