68 pin SCSI

Justin

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yo,

what adaptor do i need to connect a 68pin SCSI drive to an A2091? is it male/male?, male/female? etc, etc

cheers, JuvUK
 

Zetr0

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@Juv

the Harddisk will have a Female connector, most adapters follow this suit.

you would need a 50pin male/female to 68pin Female gender changer-

something like this (click Images for links)

SCSI 68 Pin Female to 50 Pin Female Adapter Converter (£3.98 eBay.co.uk Buy It now Free Postage)






With this adapter you will need a 68pin SCSI IDC Cable


somthing like this would be grand m8

Foxconn SCSI Cable 68pin 4 Head Twisted Pair+Terminator ( £3.80 eBay Buy It Now Free P&P)


Of course it would probably be best to use the 50pin female to 68pin female adapters like the following for the 50pin optical drive

DATAMATE SCSI 50pin to 68pin Adapter (eBay.co.uk Buy It Now £5.59 Free P&P)


That way you can use just one Cable for both devices, the cable above also provides termination.
 

TheoryBoy

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Sorry Zetr0, isnt it this one ?

ux_a09010500ux0077_ux_c.jpg


50pin male to 68pin male scsi.

This would convert the drive down to 50pin scsi, and just use the cable that came with the A2091. You might have to check termination though.

50pin scsi drives have male connectors, 68pin scsi have female connectors.
 

Zetr0

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@TheoryBoy

indeed! well found!!!
 

commodorejohn

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Is there any consideration in doing this other than getting an adapter? Is there a maximum drive size the Amiga can handle, or does that depend on the controller?
 

Justin

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thanks both for the info(y)

i've just been given a 37.5gb 68 pin known working SCSI hard drive, now this is my 1st foray into SCSI, so what is this "termination" you talk of? and do they do a male/female gender changers for terminators?

i'll be back.............to check this thread later:)

cheers, JuvUK

---------- Post added at 15:33 ---------- Previous post was at 15:31 ----------

Is there any consideration in doing this other than getting an adapter? Is there a maximum drive size the Amiga can handle, or does that depend on the controller?

drive size matters depending on os roms, scsi controller rom versions and software used

for example my A1200 uses all 60gb of it's hard drive:)
 

TheoryBoy

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You might have to search for the datasheet on your drive, but usually there is a jumper on the board of the drive to set termination. Usually in a 68pin scsi chain there is a signal terminator at the end, but since your run is short you may have to get the drive to terminate the chain (be it chain of 1)
 

xc8

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@JuvUK

For drives over 4.5GB you need a 68pin to 50 with High-Byte termination!
(also called: 9 line negation termination )
High-byte termination is not the same with bus termination!

Chris
 

Zetr0

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SCSI SCSI SCSI.... =)

Is there any consideration in doing this other than getting an adapter? Is there a maximum drive size the Amiga can handle, or does that depend on the controller?

in simple terms, there is only two limmitations

1. SCSI Controller

Older controllers are rigid in the size they can address to, although most Amiga SCSI adapters are not.

Most SCSI controllers have a Firmware this is used to calculate geometry and setup data for the device (such as removable / reselectable etc)

Some Controllers Firmware is limmited to reporting back less than the Device actually is, this can complicate installion of larger devices, however for the most part better Firmware is available that can calculate larger geometry sizes as well as improve SCSI performance.


2. OS File System (Format Boundary's)

The original Amiga OS3.0 uses SCSI.device for its formatting system, this needs to be updated to have larger than 4GB partitions, there are other devices too that can be used as long as the Device is complient or supports them. Most SCSI controllers have their own device driver.

have a look on AmiNet for SFS (Smart File System) and SCSI.device, there are many advancements that can help a lowly A1200, for lesser machines like those bound to a 68k chip, have a look for PFS3, a very impressive filesystem that can not only give support for much larger than 4GB partitions, but also improves reading / writing and the validation of data.

I will do a UAE how to set up a 40GB IDE/SCSI drive under SFS soon.



thanks both for the info(y)

i've just been given a 37.5gb 68 pin known working SCSI hard drive, now this is my 1st foray into SCSI, so what is this "termination" you talk of? and do they do a male/female gender changers for terminators?

i'll be back.............to check this thread later:)

cheers, JuvUK


Simply put my friend, SCSI is a networking chain, very similar in a lot of ways to the old BNC networks.

you have a SCSI HOST (normally the controller card) and this inquires all the devices on the chain by shouting out who's on the chain.

Devices respond with their information (RDB/MBR infos and ID's) however the HOST needs to know when the chain ends -

A little bit from a SCSI Bible (old-ish testament)
A pulse propagating along the SCSI bus will ‘reflect’ from any part of the bus that is different from the rest of it. These reflections add and subtract in odd combinations and cause the original pulse to be distorted and corrupted, thereby causing data loss. To prevent or minimize reflections from the ends of the bus, terminators are added to "absorb" the energy from the pulses.

The terminators on the SCSI bus hold the bus in a negated state, any one of up to 16 drivers could be driving the bus or none. The bus is held in the negated state as required by the SCSI protocol. The original drivers on a SCSI bus only asserted (Open collector) and the terminators were used to negate the bus. Drivers that assert and negate the bus are known as active negation drivers. The negation is less current than the assertion, the drivers are designed for 2 terminators negating the bus.

Now, this is just a basic SCSI, there are a few flavours but the one you are playing with is essentially know as LVD/SE SCSI setup and is most common in small networks / business and Home enthusiasts....

if you wanna scale it up to a few mega-terrabytes hit me up and we can discuss some HVD (High Voltage Differential) and Serial SCSI solutions =)
 

xc8

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Because you are going to convert the wide drive interface to the narrow 50 pin bus connector, this HB-Termination terminates the unused 18 pins. Non connected data lines will cause parity errors...

Also check the device if there are jumpers like 'force SE' or 'disable LVD'

Chris
 

TheoryBoy

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While the adapter may force SE mode on its own, it would do no harm to put a jumper at "Force Single Ended"

Also while in SE mode, only the first 3 bits of the SCSI id are used, from 0 to 7, I usually dont like having drives on 0, and 7 is usually the host adapter, so out of habit I put a jumper on the middle bit (pin 2 on the addr pins)

Dont worry too much, buy an adapter and give it a try.
 

TheCorfiot

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@Juzzer

Zetr0 & I ordered some multi SCSI adapters recently & I have one spare.

I'm pretty sure it would do the job for you, let Zeets confirm this & you can have the adapter as a gift...

TC :)
 

Merlin

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@ JuvUK

I'm surprised that our resident guru didn't mention this, so here goes...

With SCSI devices, there are a couple of things to watch out for. these are:-

1. LUN (Logical Unit Number). Each SCSI device on the chain has to have a separate LUN, including the controller. These range from 0 to 7, hence you can have up to seven devices on one controller :). The drive will have a set of jumpers that allow you to set the LUN.

2. Termination Power. Later SCSI drives have a jumper to set this. It's usually set to on.

3. Termination. The last device in the chain is the one that has to be terminated and your hard drive may have a jumper to set termination on or off. If it's the last device in the chain set it to on.

Alternatively, you can attach a passive terminator to the external SCSI port of the 2091. If you later attach an external SCSI CD drive, some of these also have external termination and on these it's very important.
 

johnim

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hi sorry to butt in can these adapters be used with a blizzard scsi 50 pin to 68pin hard drives as i have 2 9gb drives i think from a pc
 

Zetr0

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@Johnim

The blizzard SCSI is LVD/SE SCSI 2 complient Host so it should =)

The SCSI controller is similar to the cyberSCSI 2 device in operation and mine has had several differing SCSI SCA adapters on it.

the adapters themselfs for the most part are transparent, just make sure that that the correct setup of the device (scsi unit) is done and the rest is good.
 

Justin

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@TC

thanks for the offer m8, but you know how impatient I am :), i bought one from evilbay for £3.48 inc postage, so i didn't see the point in not buying one lol

cheers, JuvUK
 

TheCorfiot

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@TC

thanks for the offer m8, but you know how impatient I am :), i bought one from evilbay for £3.48 inc postage, so i didn't see the point in not buying one lol

cheers, JuvUK

I'm 99.99999999999999999999999999999% sure it will work fine my friend.

TC (y)
 
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