SCSI DB25 External to 50-Pin Internal

[kamiga]

Hi there.

Yeah, I think it's just a matter of pinning.

DB25 for SCSI was used for SCSI 1.  It's the old school SCSI, and many old external drives and SCSI cards had a DB25 on them.  I had a scanner with a DB25 on it once.

50-pin IDC? Is this an internal drive?

I'm pretty sure the DB25 is the external version of SCSI 1, and 50-pin IDC is the internal version of SCSI 1.

Most newer SCSI devices are backwards compatible with old cards, so even if its a newer device you should be ok.

I'll look around and if I happen to see an adapter that works I'll report back.

HTH

Keith

[kamiga]

Two questions also come up:

1> power.  How are you planning on powering those drives?  I think the power is normally on the IDC50 IIRC. (although I could be wrong )

2> termination.  You know you have to terminate the SCSI bus with a terminator, right?  So daisy chain your devices and then have a terminator at the end of the chain.

which brings up,

yes, you can have multiple devices.  I think the limit is 7 devices.  They all have to have different SCSI id's which is normally set by jumpers or a little push-button wheel thingy that lets you set it.

You know, you could probably rip the guts out of an external scsi case to get the right connections.......

Keith

[kamiga]

rkauer wrote:
 
 Almost right. You need to terminate both ends of the SCSI chain with the same type of terminators.

Thanks for an almost verification of what I already knew to be true.

 Some SCSI controllers have an internal terminator, but don't count on it.

MOST scsi controllers are terminated internally.  Because the SCSI hosts are usually the starting point of most SCSI chains, they are usually terminated.

Keith

[kamiga]

Jim,

That really is a shame.  My radio shacks around here (Pittsburgh) are all cell phone stores.  Ask about a replacement cell phone battery or cordless headset, and you'll probably be taken care of.

Ask for a 555 timer IC and they'll look at you like you are on crack.

It's really a shame because I'm just starting to get a little hot and heavy into electronics the last couple years, and sort of know enough now to be dangerous.  I liked RS in the past because they almost always had the most common components on-hand.  It wasn't unheard of to walk in with a list of popular ICs, parts, connectors, and them to have everything on hand and in stock.

I've played around with SMT components, and as long as the pitch isn't too bad on them, I can hand solder them fine.... I don't have a bench magnifier, but need one.

There are also those schmartboards, which although I've never used them, look really great for prototyping SMT stuff.

It seems the past few years there's been an increase in the number of ready made modules for tasks.  Like wireless modules for xmitting data, or LCD modules with simple interfaces.  A lot of them come out to .1 on center for breadboading.... sparkfun has a decent selection of them.

I also like the trend of these IC manufacturers to eliminate external component requirements to make them work in standard ways.  No need for external caps etc.

Keith