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View Full Version : GVP Impact A2000-HC+8 Series II SCSI Card Questions



NJRoadfan
18th September 2012, 23:23
I just picked one of these up for my new Amiga 4000 and had a few questions.

-Does the card supply termination power? I plan on using a SCSI Zip drive with the card and I know it doesn't supply any term power. Are their any mods to add term power to the bus if that is the case?

-What is the logical layout for termination purposes? SCSI cards typically have the actual controller "in between" the internal and external port with switchable termination (only disabled with devices are connected to both ports). Like the following diagram.



Term---Internal Devices---SCSI Card---External Devices---Term
I noticed that the manual states that all termination packs should be removed from internal HDs attached to the card which I thought was odd. Is it possible that the card layout is the following?



Term------SCSI Card---Internal Device---External Devices---Term
I really don't want to deal with SCSI Hell.


-This card came with Guru Rom 6.10 installed. Can I use the GVP provided utilities/drivers (FaaastPrep, etc.) to prepare SCSI hard drives? If not, are there any GuruROM specific utilities or drivers?

Orcish75
19th September 2012, 01:07
Hiya!


-Does the card supply termination power? I plan on using a SCSI Zip drive with the card and I know it doesn't supply any term power. Are their any mods to add term power to the bus if that is the case?Unfortunately the GVP HC+8 doesn't supply termination power, however this is only necessary if the last device in your chain has active termination. If the Zip drive doesn't have an option for termination power, it more than likely doesn't have active termination. Most devices that use passive termination have a row of small sockets close to the SCSI connector where you can plug in resistor networks to terminate the device. If your Zip drive has neither, you'll need to get some sort of SCSI device that has active or passive termination at the end of the SCSI cable, with the termination power jumper enabled if it's an active device.


-What is the logical layout for termination purposes? SCSI cards typically have the actual controller "in between" the internal and external port with switchable termination (only disabled with devices are connected to both ports).The GVP HC+8 has passive termination soldered onto the board right next to the internal SCSI connector. You can see the two yellow resistor packs next to each other, parallel to the SCSI connector. These can't be removed without desoldering them, so your GVP card should look like this:

Term--SCSI Card---Internal device--Term

If you have an External device as well, it'll look like this due to the non-removable nature of the GVP termination resistors:

Term--External device--Term--SCSI card--Internal device--Term


I noticed that the manual states that all termination packs should be removed from internal HDs attached to the card which I thought was odd.This is correct, only the devices that are connected to the end of the physical cable must be terminated. The reason SCSI cables are terminated is to prevent the SCSI signals from being reflected back along the cable and causing signal interference and thus read/write errors.

One other thing about termination power in active devices, ensure that only ONE device in the entire SCSI chain has it's termination power jumper enabled, all other active SCSI devices must have their termination power jumper disabled.

If you have a configuration like this:

Term--External device--Term--SCSI card--Internal device--Term

Strictly speaking you should remove the termination resistors on the GVP card to conform 100% to the SCSI standard. However, I have found in practice it's not necessary and that the settings on the SCSI devices at the end of the cables have not been set correctly if you're having problems.

Another jumper that is often overlooked when using Wide SCSI devices (68-pin connector) is the "Narrow or 8-bit" operation jumper. Not all drives have this, but if it does, this must be set if you're using a narrow SCSI controller ( such as the GVP HC+8 )

If you're using LVD (Low Voltage Differential) SCSI devices, look for another jumper labeled "Single Ended or SE operation" (Also, not always available on LVD drives). Make sure that is also enabled for operation with the GVP HC+8.


-This card came with Guru Rom 6.10 installed. Can I use the GVP provided utilities/drivers (FaaastPrep, etc.) to prepare SCSI hard drives? If not, are there any GuruROM specific utilities or drivers? Yup, you can use the GVP utilities, just make sure you set the device driver tooltype to omniscsi.device for the Guru-Rom, as opposed to gvpscsi.device for the normal GVP-Rom.

Hope you come right with your setup! :D

NJRoadfan
19th September 2012, 01:34
Unfortunately the GVP HC+8 doesn't supply termination power, however this is only necessary if the last device in your chain has active termination. If the Zip drive doesn't have an option for termination power, it more than likely doesn't have active termination. Most devices that use passive termination have a row of small sockets close to the SCSI connector where you can plug in resistor networks to terminate the device. If your Zip drive has neither, you'll need to get some sort of SCSI device that has active or passive termination at the end of the SCSI cable, with the termination power jumper enabled if it's an active device.

Hmm, I have an external SCSI Zip-100 drive. All it has is a termination on/off switch. I have had problems in the past using it with a parallel-to-SCSI cable that didn't supply termination power on its own and I know Apple II folks using Apple's HS SCSI card needed to mod it for termination power. I'll play with it and see what happens, worse comes to worse I'll add on another drive.

As for the narrow vs. wide situation, I have been down that road before with a PowerMac. The 68-pin IBM drive I used needed to be jumpered for single ended mode and I had to use a 50 to 68pin adapter that specifically had "upper byte termination" since the drive didn't have a narrow mode jumper.