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John B Black

Q: SCSI connection on PB 5300cs

I picked up a pair of 5300cs PowerBooks really cheaply and I'm doing some upgrading on one. I got an HDI-30 SCSI adapter with the intention of hooking up a Zip drive to the PB. The drive is a Zip100 Plus, with the ability to connect to either SCSI or parallel ports. On my SE/30 (OS 7.5.5) the drive is immediately recognized, but the 5300 (OS 7.5.2) balks on startup and displays a bouncing SCSI symbol with the currently selected SCSI number beside it.

I've tried coordinating PowerBook Setup and the SCSI number on the computer end, along with setting the Zip drive to match. That only changed the number that was bouncing on the screen. The computer still refused to boot beyond that point.

Any ideas?

John

G4 DA NewerTech 1.7GHz; iMac G3 500; PowerBook Firewire G4; SE/30, iPod 4th Gen, Mac OS X (10.4.11), 10.4.11 on G4; 10.2.8 on iMac; 10.3.9 on PowerBook; 7.5.5 on SE/30

Posted on Sep 12, 2008 7:56 AM

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Q: SCSI connection on PB 5300cs

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  • by Grant Bennet-Alder,Helpful

    Grant Bennet-Alder Grant Bennet-Alder Sep 12, 2008 8:55 AM in response to John B Black
    Level 9 (61,297 points)
    Desktops
    Sep 12, 2008 8:55 AM in response to John B Black
    The problem is probably not SCSI ID numbers, but SCSI Termination and Termination Power.

    The SE has an internal SCSI Hard drive. That drive is set to provide the required 5 Volt power onto the Termination Power pin on the SCSI cable. External Terminators use this power to "pull up" the signals toward 5 Volts when they are not being driven low, effecting Termination.

    The 5300 does not use a SCSI drive internally, and does not provide Termination Power onto the Bus. It predates the PowerBooks \[3400 and later models] that deliberately provide Termination Power onto the Bus.

    The Zip Plus makes many (in my opinion, far too many) compromises to support its use on a parallel port -- the most grievous of which is to cut half the SCSI signals and re-drive them to the second connector, thus negating the effects of any Terminator applied to the second connector. You must either use its internal Termination switch to effect Termination, or use an "in-line" Terminator.

    It is entirely possible that even with very short cables there will not be enough Termination, and that the Termination Power required will not be supplied by the Zip Drive. In that case, you may need an additional external SCSI device to supply Termination power so that an external in-line Terminator can do its job.

    If this all sounds like "word salad" to you, please post more info about exactly which cables \[how many pins to how many pins] and which Terminators are used in your set-up and readers will work to get you going again.

    Message was edited by: Grant Bennet-Alder
  • by John B Black,

    John B Black John B Black Sep 12, 2008 9:57 AM in response to Grant Bennet-Alder
    Level 2 (320 points)
    Sep 12, 2008 9:57 AM in response to Grant Bennet-Alder
    Thanks, Grant. Makes perfect sense. It's been a long time since I've dealt with SCSI issues, but I follow your logic. I'll have to try hooking up a terminated hard drive after the Zip Plus; unlike some other Zip models this one doesn't have an external termination switch. I'll see what happens and post my results.

    John
  • by Grant Bennet-Alder,Helpful

    Grant Bennet-Alder Grant Bennet-Alder Sep 12, 2008 2:09 PM in response to John B Black
    Level 9 (61,297 points)
    Desktops
    Sep 12, 2008 2:09 PM in response to John B Black
    "I'll have to try hooking up a terminated hard drive after the Zip Plus; "


    Do not hook up anything after the Zip Plus -- its second connector is effectively NOT a SCSI connector. To use another device it must be installed before the Zip Plus. Assume the second connector on the Zip Plus is only for a serial printer -- not for another drive and not for a Terminator.

    Every other well-behaved SCSI device has a metallic connection from one end of the Bus to the other -- they never attempt to break and re-drive signals because when you do, Termination does not work.

    If you have a purple Zip drive cable, it is not magical -- it is merely a 25-pin straight-through shielded SCSI cable. You can substitute any other SCSI cable as long as the connectors are the right male and female type, or you can use sex changers to get the setup you need. A Mac "System Cable" the regular 25 to 50-pin Centronics style, can be used where needed facing either direction.

    Message was edited by: Grant Bennet-Alder
  • by Jan Hedlund,Solvedanswer

    Jan Hedlund Jan Hedlund Sep 13, 2008 3:47 AM in response to John B Black
    Level 6 (9,901 points)
    Sep 13, 2008 3:47 AM in response to John B Black
    John,

    but the 5300 (OS 7.5.2) balks on startup and displays a bouncing SCSI symbol with the currently selected SCSI number beside it


    The PowerBook 5300cs appears to be in HD Target Mode (SCSI Disk Mode). This is used to connect a supported PowerBook computer (such as this one) to a SCSI desktop Mac. It means that the PowerBook would act as an external hard drive to that Mac.

    I got an HDI-30 SCSI adapter


    Does the adapter plug have all 30 pins (not only 29)? Unless the adapter has a switch, it will then make the PowerBook operate in HD Target Mode (SCSI Disk Mode).

    In order to connect an external hard drive to the PowerBook, a 29-pin plug is needed (or a third-party 30-pin adapter with a switch set in the correct position).

    Details about SCSI can be found in the manual.

    Jan
  • by John B Black,

    John B Black John B Black Sep 13, 2008 11:02 AM in response to Grant Bennet-Alder
    Level 2 (320 points)
    Sep 13, 2008 11:02 AM in response to Grant Bennet-Alder
    OK, thanks for the additional information. This little project is a low-priority side interest that has to fit into busy family life, so my progress is liable to be slow. I'll update as I'm able to tackle it further.

    John
  • by John B Black,

    John B Black John B Black Sep 13, 2008 11:30 AM in response to Jan Hedlund
    Level 2 (320 points)
    Sep 13, 2008 11:30 AM in response to Jan Hedlund
    Thanks, Jan. I've got a lot going on now, so progress on this little project will be slow.

    In answer to your question, the adapter has 25 pins, which matches the Zip drive's connector. It does have an on/off switch.

    **

    Flash! I did some more fiddling around with the setup, the only things being to change the SCSI ID on the back of the Zip drive to 6 and set the adapter switch to off (it was set to on), and bingo! It's working. PowerBook Setup has SCSI Disk Mode set to 5 so your comment made me wonder what would happen if I made the two IDs different. SCSI Dock "On" must work with Target Disk mode, and that change alone probably fixed things. The Zip drive appears to be self-terminating, going back to Grant's comments.

    John
  • by Jan Hedlund,

    Jan Hedlund Jan Hedlund Sep 13, 2008 7:45 PM in response to John B Black
    Level 6 (9,901 points)
    Sep 13, 2008 7:45 PM in response to John B Black
    Hi John,

    In answer to your question, the adapter has 25 pins,


    The plug that I had in mind was the square one matching the PowerBook's SCSI port.

    PowerBook Setup has SCSI Disk Mode set to 5


    This only means that the PowerBook, in HD Target Mode, will appear as a SCSI ID 5 hard drive to a desktop Mac.

    SCSI Dock "On" must work with Target Disk mode, and that change alone probably fixed things.


    Yes, that is correct. The switch "connects/disconnects" the 30th pin (which controls whether or not the PowerBook will operate in HD Target Mode).

    Glad to hear that it is working.

    Jan
  • by John B Black,

    John B Black John B Black Sep 14, 2008 11:22 AM in response to Jan Hedlund
    Level 2 (320 points)
    Sep 14, 2008 11:22 AM in response to Jan Hedlund
    Jan,

    I must have had my brain in neutral concerning the pin count. As you say, it's a 30-pin square connector with a switch that shorts out one pin for Target Disk Mode.

    I think I may still need an inline terminator as shown in the owner's manual, as mounting of the Zip drive is hit and miss right now.

    John
  • by John B Black,

    John B Black John B Black Sep 14, 2008 11:45 AM in response to John B Black
    Level 2 (320 points)
    Sep 14, 2008 11:45 AM in response to John B Black
    Correction. 30 pins for TDM, 29 for SCSI device, as I understand it.

    John
  • by Jan Hedlund,

    Jan Hedlund Jan Hedlund Sep 14, 2008 2:01 PM in response to John B Black
    Level 6 (9,901 points)
    Sep 14, 2008 2:01 PM in response to John B Black
    Yes, an adapter/cable without a switch, has 30 pins in the version used for HD Target Mode (SCSI Disk Mode) and 29 pins in the one for an external SCSI hard drive (or other SCSI device).

    An adapter equipped with a switch always has 30 pins (the position of the switch determines whether the adapter shall appear as a version with 30 or 29 pins).

    Jan