RSX11M+
Veteran Member
- Joined
- Feb 14, 2011
- Messages
- 1,075
I know this thread is one of several on ZIP disks, but I have a specific concern that bears talking about.
Since I'm a new member of the SCSI / PDP-11 club myself, I've been lurking on those threads waiting for it be covered - but nobody has yet brought up the "COD" (Click Of Death) problem once well known to ZIP drive owners.
There is an excellent technical overview of this on grc.com and even some free software to help detect susceptible drives, write-damaged disks, along with specific recommendations for cartridge care and inspection. Prepare yourself for a bit of reading, as he delves into the subject in several pages. Please read them all if you're not already acquainted with the topic.
I am assembling resources to be able to share ZIP disks between PC based PDP-11 emulators, and my real systems. It turns out my MAC II collection has a number of drives that will serve nicely in this capacity, and should be of old enough vintage to be reliable (prior to the mfg runs known for COD) Nonetheless, I plan to qualify them by testing using Steve's utilities and to inspect all my disks for damage and readability before using or relying on them.
Having recently researched these potential problems and what I might do to preclude them, my purpose here is to both share this information and ask for other's comments and experiences.
To summarize:
The ZIP drive Click Of Death (COD) syndrome resembles characteristics of a Hardware Virus. It is possible to damage a ZIP cartridge in such a way that it is highly likely to damage the drives in which it is inserted. The resulting drive damage is then capable of inflicting the same harm upon other disks, and thus spreading to more units as if a "contagion" had taken root.
Additionally, some disks can have their format overwritten by an errant drive or one with intermittent power during a write operation. This can not be easily detected until data loss occurs, unless specifically tested for.
Both types of error, can cause a ZIP drive to exhibit COD behavior.
Perhaps I'm just late to the party, and this information is already universally known to everyone else. But with so many new members "discovering" the usefulness of this hardware for the first time, I thought it prudent to start this thread.
Since I'm a new member of the SCSI / PDP-11 club myself, I've been lurking on those threads waiting for it be covered - but nobody has yet brought up the "COD" (Click Of Death) problem once well known to ZIP drive owners.
There is an excellent technical overview of this on grc.com and even some free software to help detect susceptible drives, write-damaged disks, along with specific recommendations for cartridge care and inspection. Prepare yourself for a bit of reading, as he delves into the subject in several pages. Please read them all if you're not already acquainted with the topic.
Steve Gibson is a highly reputable technical guy and I usually find his thinking and software well founded. His writings on COD are among these. Remember though, he's a geek like the rest of us, so his style reflects this heritage.
I am assembling resources to be able to share ZIP disks between PC based PDP-11 emulators, and my real systems. It turns out my MAC II collection has a number of drives that will serve nicely in this capacity, and should be of old enough vintage to be reliable (prior to the mfg runs known for COD) Nonetheless, I plan to qualify them by testing using Steve's utilities and to inspect all my disks for damage and readability before using or relying on them.
Having recently researched these potential problems and what I might do to preclude them, my purpose here is to both share this information and ask for other's comments and experiences.
To summarize:
The ZIP drive Click Of Death (COD) syndrome resembles characteristics of a Hardware Virus. It is possible to damage a ZIP cartridge in such a way that it is highly likely to damage the drives in which it is inserted. The resulting drive damage is then capable of inflicting the same harm upon other disks, and thus spreading to more units as if a "contagion" had taken root.
Additionally, some disks can have their format overwritten by an errant drive or one with intermittent power during a write operation. This can not be easily detected until data loss occurs, unless specifically tested for.
Both types of error, can cause a ZIP drive to exhibit COD behavior.
Perhaps I'm just late to the party, and this information is already universally known to everyone else. But with so many new members "discovering" the usefulness of this hardware for the first time, I thought it prudent to start this thread.