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ESDI Cables

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Shadow Lord

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Sorry, but I couldn't figure this one out on my own: Are ESDI cables and MFM cables physically the same? I know the signalling is different (i.e. don't connect ESDI to MFM) but can the 20pin and 34pin cables form an MFM drive be used to connect an ESDI controller to ESDI HDD? Thanks.
 
MikeS said:
True, but the cables are the same (except for the 'twist' issue of course).
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But the twist is only an issue if I want to do the equivalent of cable select for drive 1/drive 2. If I jumper the drives this shouldn't matter, correct?
 
Chuck(G) said:
Funny thing about the "twist"--for unit select 1-3, it's the same for both ESDI and ST412. (26,28,30)
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Sorry, didn't mean that there was a difference, just that it's an issue to keep in mind when taking cables from one system/drive(s) to use in another where the drives may not be jumpered the same; sorry if it's obvious but you never know...
 
Well, I asked about the cables because a friend of mine passed on a free ESDI controller to me. And of course like all things free it comes with caveats. E.G. it comes with a drive but no cables. The other issue of course is the ever present: "but does it work" :D. I looked over the card and it looks to be in good shape. However, looking at the 34 pin connectors on each one a ground pin is broken (i.e. 1 out of the 17 on each connector). Would this affect operation? I.E. if pin 6 dos not have a ground or should it not matter?
 
Chuck(G),

Not sure what brand it is. I have to check when I get home but I think it was an Adaptec. I briefly looked at it last night at 11 before crashing. As for drives he supposedly has one and will send it to me if he finds it. if not, eBay. Thhe controller was free so I am in no rush for a drive. I was looking at a maxtor that went for a bout $20 last week. Unfortunately, I was not sure if I was going to be able to use it so I did not bid on it.
 
5¼" FH ESDI drives are usually nice great hunks of iron--built like battleships. Transfer rate is approximately twice that of an MFM drive and most controllers themselves look just like IDE drives--that is, they support most of the same command set as IDEs. Maxtor and Miniscribe both had very good lines.
 
Shadow Lord said:
Chuck, does the same apply to the HH brethren?
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I don't know, as I began moving to IDE or SCSI about the time that HH ESDI drives started to become common. It was pretty obvious that ESDI was destined to be a dead-end interface. A SCSI drive had about the same price point, the choices in controllers were better, there as only one cable, the cables could be longer and you could put more than 4 SCSI drives on a cable--and most important, you could also run tapes, scanners, etc. from SCSI. To the best of my knowledge, there were no ESDI tape drives or CD drives.
 
I have a few Maxtor XT-4170E, XT-4380E and/or XT-8760E drives, and a Micropolis 1355 or 1558 drive. I have used these with Dilog DQ696, Emulex QD21, and Sigma SCD-RQD11-EC controllers on Q-Bus PDP-11 systems and they seem to work fairly well in that environment. I don't currently have any ISA bus ESDI controllers.

For a while you could find reasonable deals on ESDI drives on eBay, but that doesn't seem too common any more. Still, easier than finding an inexpensive and working MFM RD54 / XT-2190.

This recent XT-8760E for $61 was more that I would want to pay for one: http://www.ebay.com/itm/220935403328
The next one he sold for $21.50 seemed more reasonable: http://www.ebay.com/itm/220939834693

I only have a couple of sets of cables between the drives and controllers I have. I am going to build my own straight through 20-pin and 34-pin cables for single drive per controller setups. I have the cable and header connectors, just need to pick up some card edge connectors.

-Glen
 
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