Hard Drive Problems on the Centris and Quadra 610 with Silverlining 5.5 or Later

It is out of sheer desire to help others overcome the year-long disaster that I went through, that I would like someone to be able to document this somewhere. Please take note, this affects all Centris 610 and Quadra 610 machines, but not the 660av.

Quadra 610There is a case, given several parameters, where a lock-up on a Centris or Quadra 610 will always cause a flashing question mark at boot time. It is also easily solvable by booting from a Disk Tools disk – without running any programs. The case is this:

  • You are using a Centris 610 or Quadra 610 with System 7.5.5 through Mac OS 8.1.
  • You do not boot from a hard drive that contains an Apple or FWB driver.
  • You are using Silverlining HD Software 5.5 or higher (including 5.8.1) on a non-Apple hard drive.


After working with the machine for a while, there would be a solid freeze – no mouse movement – and a warm restart won’t work. Hitting the programmers switch does nothing, and hitting the reset button causes the machine to reboot to a flashing question mark. If you simply insert a bootable floppy (such as Disk Tools), the machine will boot up and mount the hard drive.

Simply choosing Restart will restart the machine fine from there. It seems that the drive looses it’s boot flag whenever the machine crashes, and simply remounting it with Disk Tools causes the boot flag to be reset. A stupid error.

Trying to Fix It

I wiped the drive and reinstalled the system software to find the same thing. I installed Mac OS 7.6, then 7.61, and still the same thing. I replaced the drive with another brand (the original was an NEC 1 GB, I replaced it with a Seagate 1.2 GB) – same thing.

Only when I put the original 230 MB Apple-branded Quantum drive in the machine did the problem go away. I once even tried my Quantum Atlas 9 GB (thinking Quantum drives were the answer); it failed. It clearly was a dependence on the Apple driver, for some reason.

Inside the 610

I’ve owned several 610 series machines, from the 20 MHz Centris 610 to an upgraded 32 MHz Quadra 610 with a clock chipped Sonnet QuadDoubler with a V-chip (cold cathode) metal glued to the heat sink. I’m comfortable with hardware solutions and feel well versed in the 610 ROM.

There are a couple of notes I wish to make mention of about Apple at the time the 610 was released.

For those of you that remember, SCSI Manager 4.3 was a big deal. It was toyed around with in System 7.5, then built into the operating system afterwards. In fact, there were several problems with the SCSI Manager 4.3 extension with System 7.5, and several machines were suggested to remove it.

The 610 class machines were among those affected, and Apple promised a fix for them. This was a key mention by Apple, because the 610 ROMs included a base implementation of the SCSI Manager 4.3 async driver. We 610 users had the async built in (I’m recalling this from a couple of years ago – please read on anyway if you need to correct me), and we were the first machines that Apple bragged about async capabilities.

Now the async was fully implemented in the 660av machine, as part of the ROM, and therefore Apple said that the 4.3 extension could be kept in the System Folder, because it wouldn’t do anything anyway (since the same version extension was built into the ROM).

Here’s the catch. Both the 610 and 660av declare the same version of the SCSI manager in their ROMs, but I have a sneaking suspicion, just from the dialog of the time, that there is a difference. With System 7.5.1, Apple built 4.3 into the System file, but also claimed 4.3 support for 610 class machines (which should be unnecessary, right? [Okay, there may be flaws in that, but please continue]).

Starting with System 7.5.1, I had trouble with two 610 machines that were on an ethernet network locking up and coming up with the flashing question mark. We actually created boot disks, just in case the machine crashed, to boot cycle the drives so that they worked again for about six months.

FWB Hard Disk Toolkit to the Rescue

Finally, I decided to try another hard drive partition software, FWB.

FWB solved the problem, and I found some information from FWB’s site concerning compatibility with machines. FWB made changes in their driver software when System 7.5.1 came out to support the new SCSI Manager 4.3 and to (and I quote) also fix SCSI Manager 4.3 compatibility problems with the Quadra and Centris 610.

It’s my opinion that Silverlining does not have these changes (since I’ve religiously used Silverlining on all my clients machines for nearly six years now) and that the issue is really with the 610 ROM. Because the 4.3 code differs in the 610 from any other 4.3 internal ROM on any other Mac made, I keep feeling that it should have been named 4.3b12. But because the 4.3 version is exactly the same as the SCSI Manager used today, the System file would never replace the existing ROM code with the 4.3 code built into the system file. Thus, the 4.3b12 code runs on the 610 machines.

I suspect that the FWB driver checks the gestalt ID of the machine when the drive is first recognized and immediately patches the ROM code as <4.3 so that the system software will replace the SCSI Manager with it’s built-in 4.3 code.

Testing My Hypothesis

For those of you laughing or saying I’m a fool, here’s my real world test.

I created two NEC 1 GB drives with Silverlining and made the second drive bootable. We booted off the drives – everything worked fine until the 610 froze. When I rebooted, I saw a smiling Mac, a video reset, and then a flashing question mark.

To prove my point (to the client), I reformatted the first drive with FWB HDT 2.x (whatever at the time) and did not make it bootable. When the machine restarted this time, the FWB driver was read first, the Silverlining driver next, and the machine booted fine.

It is, for a programmers note, possible to call the version number of the running SCSI Manager in Macsbug. If you boot off of a drive on any Macintosh, whether you load Silverlining, Apple, or FWB, Macsbug will report this string (“SCSI Manager 4.3”).

In the case where I booted from the Silverlining drive only on the 610, the string reads (“SCSIManager 4.3”). This is not a typo – it is a reproducible string. If you run System 7.5 on an Apple drive without the SCSI Manager 4.3 extension, the string also reads “SCSIManager 4.3,” but if you insert the extension it reads “SCSI Manager 4.3” (note the space between SCSI and Manager). I’ll admit, this is subtle, but I cannot convince myself that the ROM is indeed the current SCSI Manager 4.3 that is built into the system file.

In short, for those of you bored out of your mind, FWB HDT Toolkit should be used on Quadra and Centris 610 machines with non-Apple drives. If you have frequent freezes that give you flashing question marks, switching to FWB should solve the problem.

If anyone has any question about this, please feel free to ask. I’m long winded, but I attempt to be thorough.

Final note: I have not experienced this problem with any other Quadra class machines, including the Performa 475/575 series (I have owned both Performa types). The Quadra 700 has a similar flashing question mark problem, but it is not related to this and does not have these exact symptoms.

Scott L. Barber <serker@earthling.net>
Pres/CEO, SERKER Worldwide, Inc.
Providing Hardware/Networking/Telecomm for 13 years

Scott L. Barber posted this to Quadlist, the listserv for users of 68040-based Macs, on December 11, 1997. It is reprinted with his permission.

Webmaster’s note. You may also be able to solve this problem using Drive Setup 1.3 or 1.3.1. This software works on 68040-based Macs and Power Macs. It is compatible with a limited number of third-party hard drives. I maintain an ongoing list on Low End Mac’s Drive Setup 1.3 Compatibility page.

Keywords: #silverlining #centris610 #quadra610 #scsimanager43 #harddisktoolkit

Short link: https://goo.gl/akqSqj