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View Full Version : max length of an 8" floppy drive cable



retrogear
November 9th, 2015, 01:54 PM
My external 8" floppy drive enclosure has maybe an 8" ribbon cable. I would like to add a 50 pin SCSI extension cable. How long can it be w/o data loss? Would 24" be too long?
I'm using S100 type controller cards.

Larry G

pjh
November 9th, 2015, 02:14 PM
Hi Larry,

I have a 36" 50 pin cable on my external drive enclosure with two Shugart SA800s. The SA800 OEM manual says on page 14 that you can have a maximum of 10 feet of twisted pair cable. I am not sure how that translates to flat ribbon. Basically, any reasonable lenght should not cause problems.

Phillip

Nama
November 9th, 2015, 02:36 PM
I have about 6-7ft of 50pin flat ribbon cable to my 8" Shugart drives...seems there is no issues.

Chuck(G)
November 9th, 2015, 04:20 PM
Yup, old technology. OC signals terminated in 150 ohms. I've had 10 ft. ribbon cables to drives with no problems.

However, this assumes that your controller uses 7432-type drivers.

retrogear
November 9th, 2015, 05:05 PM
>I've had 10 ft. ribbon cables to drives with no problems.
I would have never guessed it could reach that far. If the program asked for the next disk, I could change it w/o leaving my easychair :p
(Of course, then I'd need a 10ft keyboard extension too)

>However, this assumes that your controller uses 7432-type drivers.
Well, hopefully. It's a CompuPro DISK1 or a Zenith Z207.

>OC signals terminated in 150 ohms.
I'll have to check that too.
Should there always be termination or only after so many feet?

Chuck(G)
November 9th, 2015, 07:26 PM
No, there should always be termination. The signal lines are driven by open-collector gates. You need something to pull them up. 3.5" floppies often use something like 2K for termination But nobody's using 10 ft. cables on those, I suspect.