With what kind of SCSI drives does CS-PPC with?

[keropi]

oh, thanx Hacky!

[Zetr0]

then theres passive and active terminators

as the PPC provides termination power you will only need a passive ( a device can do this if you set the jumpers properly) on the other hand a passive terminator should only set you back about 10 Euros.



then theres LVD, Low voltage differential (which i believe the PPC scsi module is) just make sure you dont get HVD, high voltage differential, devices.

setting up a solid SCSI can be really scary, difficult for first time users, it takes some time and a lot of asking questions to get it going.... and some cases black magic and virgin sacrifices! lol .

the best description i could really give you is that SCSI is more like networking than IDE, whereby scsi devices are relatively smart compared to dumb/save controlled IDE devices.

I have found that in the realm of SCSI you can never have enough infomation so here are some light reads

heres a good tech comparison of ide and scsi http://www.pcmech.com/show/harddrive/79/

heres a good SCSI overview http://www.pcmech.com/show/harddrive/153/

how to setup a chain (internal / external etc.) http://www.2ndchancepc.co.uk/basic-scsi-faq.html

if you get bitten by the knowing more about scsi after that theres
http://www-128.ibm.com/developerwork.../pa-spec8.html


I have several machines on scsi after a lot of hassle but its still worth it (even my dos box), both my Amiga's will run SCSI as i have adapters for them too

anyways i hope the info helps.

[keropi]

slowly I understand more...

[keropi]

now THIS MUST be it!

http://cgi.ebay.de/SCSI-III-Ultra-32...QQcmdZViewItem

and 2 of these terminators? (active ones?) http://cgi.ebay.de/SCSI-III-Terminat...QQcmdZViewItem

[Zetr0]

wow, nice cable, 68 Pin SCA,
(make sure you have 68pin scsi 3 devices or an adapter that allows for LVD *the cheap ones dont btw*)

The terminator is an active one but are you sure this is what you require if you look at the cable it already has a passive terminator attached at the end. so i doubt you will need any further termination.

but its always good to ask questions, no question is too silly when it comes to scsi.

[patrik]

Passive terminators, if you mean the old resistor pack style, is sufficent up to Fast SCSI (10MHz), but the CSPPC can do Ultra SCSI (20MHz) and for that active terminators are required.

If it is a LVD capable terminator, make sure it says SE/LVD or else there is a chance it is some cheapskate crap which is not SE compatible. SE = Single Ended, which is the type of signalling "regular SCSI" uses up to 20MHz. This goes for the terminator usually attached at the end of Wide SCSI cables too.

IMHO I would recommend the rounded cable which adaptec sells, it is very slim and extremely flexible and does not have those very common big obstructive plastic turds near the connectors where the cable goes from round to normal. It is the best rounded cable I come across, period. Here you can sortof see how it looks.

I bet it can be found elsewhere too, as adaptec most likely doesn't manufacture them by themselves. The adaptec part number is 1494704-00 anyhow.

[Zetr0]

Zetr0's first rule of SCSI

1) in the world of yummy scsi.... you get what you pay for....

a team m8 from many moons back told me that... and no truer-a-word spoken

[BinoX]

I generally just buy active terminators whether I need them or not.. it's well worth it... Hmm.. I'll take a pic of my SCSI tower later for yah.. That was fun to build
Had a few troubles along the way, but once you've got it there it goes like hell lol

I've been using SCSI since the arrival of PC CD Burners...
My 1st SCSI burner was a 2x write once only internal burner running off an adaptec ISA SCSI card Set me back about £600.. ah, those were the days.. (That burner is now in my amiga scsi tower.. lol... largely 'cause it can read the most scratched of CDs)



EDIT:
Added pic in: http://eab.abime.net/showthread.php?t=24659

[keropi]

I got 2 x scsi iii u320 terminator intern lvd/se 68pol and a scsi iii ultra 320 lvd rundkabel ... Now i think if i get the adaptor thingie, or a real scsi hdd ...

[alewis]

Originally Posted by Zetr0

then theres passive and active terminators

as the PPC provides termination power you will only need a passive ( a device can do this if you set the jumpers properly) on the other hand a passive terminator should only set you back about 10 Euros..

Not quite; the PPC uses ultra-scsi SE signalling, in which case an active terminator is the only option. Technically, it is mandatory under from SCSI-2 onwards. Also, never rely solely on device-termination once you go beyond Fast-SCSI2 (10mbit, 8bit).

For a SCSI-noob, I'd recommend NOT using device termination at all, and use an active terminator at the end of the chain. Apart from the fact that active terminates better, it also supplies cleaner current. Terminating the chain with only a terminator has a hidden benefit; if you re-org the device layout, you avoid forgetting to unterminate the terminated device... and avoid a headscratch when the bus fails/issues - because the put the terminated device somewhere other than the end :-)

then theres LVD, Low voltage differential (which i believe the PPC scsi module is) just make sure you dont get HVD, high voltage differential, devices.

No, the PPC is Single Ended (SE) SCSI, ie max 1.5m chain, uses a 20MHz, 16mit bus for a max bandwidth of 40MB/sec. That chain length *is* important. Trying to use a longer cable *will* result in issues. Been there, done it, tested it, seen it. Buy decent quality UW rated cables - if you can, get hold of the old Compaq server internal cables (assuming you have a tower case.)

However, the warning about HVD (aka diff-scsi) drives is all too true. Do not put HVD drives on a "normal" SCSI chain. In theory one can with an adaptor, but even then I wouldnt risk it.

LVD devices *are* backwards compatible, but will only run at 40MB/sec ie 20MHz/16bit. That said, the PPC is now, what, 10-15 years old? I haven't used an LVD device on my PPC, so I'm basing that statement on the assumption that an LVD device that is fully compliant would work on a fully compliant bus. I have used LVD devices on an Adaptec 2940UW ok, but that chipset came out after the LSI 770 chipset the PPC uses. caveat emptor applies; there are situations/implementations where the bus can lock, even under SCSI-3, when mixing newer drives on older busses.

HVD is an entirely different kettle of fish, using far greater voltages to extend the max cable distance in the bus.

setting up a solid SCSI can be really scary, difficult for first time users, it takes some time and a lot of asking questions to get it going.... and some cases black magic and virgin sacrifices! lol .

Too true! SCSI becomes "easy" when you get used to it. Many peeps are scared off by device ID and termination; consider ID the equivalent of IDE M/S jumpers. Termination is easy; each end of the chain and not anywhere else.

Major tip. Buy quality cables, terminators, and if you buy SCA (80 pin drives), QUALITY SCA-68 adaptors, NOT the cheap junk found on ebay.

Why? Ok, the cheap junk will [probably. 99.9% sure] suffice for ultra-wide operation to 40MB/sec. BUT some of these do not follow the spec for termination, impedance, etc. The risk is, you buy and handful. Then you get the SCSI bug and go SCSI in the PC. Of course, you dont want old hat technology, so you buy a U160 or U320 card, or even go RAID. Such controllers are plentiful on ebay. You buy a handful of drives. You have some (or buy some more) cheap SCA adaptors. And the bus doesn't run at rated speed. Best place to purchase these? scsi-4-me.com

But check the link on the adaptors: http://www.scsi4me.com/product_info....oducts_id=1038



Every machine in the house is SCSI, bar some large IDE storage drives, and of course the optical drives. Its just soooo superior. Put it like this, installing netware from an 8x SCSI CD drive is faster than using a 32s IDE drive. Its all down to the multi-tasking nature of the bus.

Best link in the world for SCSI is

http://www.scsifaq.org/

It hasn't been updated in 3 years, but then SCSI has hardly evolved since then anyway (bar SAS), even U640 seems to have come to a standstill.

Just about all the info you will need is there, but tween Zetro, binox and meself we can answer your questions...