Note the following nomenclature changes: The feature remains the same, only the name has changed.
A number of internal optional links and NAND gates on the circuit card can create further selectable operational features.
These type of computers, at that time, were mostly invulnerable to improper access by unauthorized users since they were installed, at least for the most part, in high security computer room environments.
However, during the 's, the rapid growth of desktop systems, including the many models of IBM-compatible Personal Computers, contributed to open up a whole new domain of computer systems including interconnected world-wide networks which are now in operation.
At present, all three "levels" of technology such as the PC's, Mini's and Mainframe computers are networked together. This has resulted in malicious codes, such as viri, being able to create extreme problems for two components of these interconnected systems, i.
Examination of damage caused by viri and other malicious codes indicates that it is the system storage devices, in particular, which can be the most severely damaged by malicious codes or unauthorized modifications.
This is the area where all "data" resides which includes all the user application data e. A single incident of contamination by a malicious code may totally erase or render useless any storage device the previously mentioned second component of its data in a manner so as to prevent even the most knowledgeable programmer being able to recover that data.
Malicious codes can also contaminate the system's central processor and memory the first-mentioned component. Therefore, one of the items desired is the ability to effectively prevent the write function whenever and wherever a computer's operational needs do not require the write function.
That ability to prevent the write function should also have the capability of operational error attempt to write a readonly database programs accomplished in a manner that system operators and users can easily understand so that the level of protection will be effectively increased.
In some applications, it may also be desirable to be able to prevent "read" access as well in particular areas that may require some limitation to the specific operating system or application system software for reasons of "restricting functionally" to only authorized tasks.
Many of the magnetic tape or disk storage devices have offered some kind of ability for "turning OFF" the "write" function. Large mainframe computers have used secondary memory devices in the form of tape and disk drives with it being quite usual to perform an operation which results in "reading" from one device and "writing" into another device at the same time.
In these cases, the tape drives and disk drives have built-in circuits and a "write protect" switch at the hardware level that, by activation, prevents any accidental loss of data or corruption of program material while an operator is performing routine operating procedures.
Built-in write protection has also been a standard feature on many mini-computers which enables an operator to quickly and totally protect program material from being lost or adulterated during some part of an operating procedure where a mishap might occur.
This type of feature, however, has not been generally available on the majority of desktop computers. Furthermore, this type of feature does not include all the desired functions that are presently required. Some manufacturers have included a hard disk power OFF switch on Personal Computers but this feature has only been seen in laptops where battery conservation was the motive.
A "write protect" device also exists for floppy disk technology wherein the "write protect" device takes the form of a notch in a floppy disk's case, which notch can be covered with a removable adhesive tab 5.
The floppy disk drive can sense optically or mechanically whether or not that notch is covered by the tab and, as a result, decide if that disk is "write protected". This technique will only guard against accidents in the nature of over-writing valuable data stored on a floppy disk.
A known write protect control circuit for computer's hard disk systems is described in U. That circuit in U. That common control bus includes a first device "select wire" to select a first disk drive device and a second device "select wire" to select a second disk drive device.
Only one of these device "select wires" can be selected activated at any one time by the disk controller to place one of the disk drives in a standby mode.
That common control bus also includes a "write fault" wire which can be activated by either of the disk systems whenever a selected disk system cannot accept data being sent to it. Activation of the "write fault" wire informs the controller that the data was not written as requested.
A "write gate" wire is also provided in the common control bus which provides a "write gate" enable signal whenever data is to be recorded on a selected disk. These are all common features which normally exist in personal computers.
However, as described in U. A switch associated with the "write protect" device can be activated to prevent any "write gate" enable signal from being applied to a selected disk drive device when that device is to be protected, i.
However, the "write protect" device will allow a "write gate" enable signal to be applied to a selected disk drive device when that device is unprotected with the switch being in the other "unprotected" position.
When the "write protect" device prevents a "write gate" enable signal from reaching a selected disk drive, it also applies a signal to the "write fault" wire to inform the controller that no data has been recorded as requested by the controller. This type of "write protect" device only allows for a limited number of protective functions.
It is a further object of the present invention to provide a write protection circuit for computer data storage devices which can operate in a number of different modes providing a plurality of selectable protective features. A write protect device for a computer, according to a further embodiment of the invention, wherein the latch circuit has a latch control pin connected to an output of a second inverter in the circuit assembly, the second inverter's input being connected to one terminal of a first three terminal connector with an electrical jumper being located between that one terminal and one other terminal of the three terminal connector, one of the other terminals being connected to ground and a second of the other terminals being connected to an output of a third inverter whose input is connected to a RESET line of the computer, the electrical jumper being connected to the terminal connected to ground allowing any changes to the latch circuit caused by a change in the switch position to take place immediately while the electrical connector being connected to the other terminal prevents any changes to the latch circuit output from taking place until after a reset of the computer.
In this particular prior art device, a write protect device 32 is inserted in a common control bus 30 consisting of 2 device select wires 36 and 35, a write fault wire 37 and a write gate wire A signal on device select wire 35 will select disk drive device 92 whereas one on device select wire 36 will select disk drive device 94 for activation and place the selected disk on standby.
Only one of the disk select wires 35 or 36 is activated at any given time by disk controller 90 so that only one of the disk drive devices can be enabled at any one particular time.
The "write fault" wire 37 is one that is activated by either of the disk drive devices when, for any reason, a selected disk drive device cannot accept data being sent to it over a data bus.
An appearance of a fault signal on the "write fault" wire 37 informs the disk controller 90 that the data was not written as requested.Artifact abebcccf8bf90a0fd3bb78ba3f File rutadeltambor.comp/src/core/sqlite3.c — part of check-in [d77de0d] at on branch vs An attempt was made to open a CA database session, but there are already too many active sessions.
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0: ERROR_INVALID_FUNCTION: 0x1: Incorrect. Fish disks 1 - - Amiga-Stuff main index Back. The commands attr, deleteattr, displayattr, delete, get, list, set, setreading, setstate, trigger can take a more complex device specification as argument, which will be expanded to a list of devices. A device specification (short devspec) can be: a single device name.
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