Hardware circuit for securing a computer against undesired write

Details Hardware circuit for securing a computer against undesired write Hardware circuit for securing a computer against undesired write

1993-11-17

1996-09-24

Chan, Eddie P.

Boots, shoes, and leggings

395439, 364DIG1, 3642481, 3642468, 3642469, 380 4, G06F 1312

Patent

active

055599931

ABSTRACT:
A write protect device for a computer comprising a hardware circuit with a switch connected to an internally installed circuit card which has cable connections between data storage device drives and a drive controller cable, the circuit card intercepting control lines used for drive selection and control. The switch is connected to inputs of a latch circuit which, in one position of the switch, generates *READONLY and READONLY signals at outputs of the latch circuit and, in a second position, *DISABLE and DISABLE signals at other outputs. To enter a read only mode, the circuit card includes an inverter and a NAND gate in a *WRITE GATE line to the data storage device drives with one input of the NAND gate being connected to the *READONLY line from the latch circuit which will prevent any *WRITE GATE signal from reaching the data storage device drives when the *READONLY line is activated. A further inverter and a NAND gate intercepts a *DRIVE SEL line to the data storage device drives with the NAND gate having one input connected to the *DISABLE line from the latch circuit. When the *DISABLE line is activated to enter a disable mode, that NAND gate will prevent any *DRIVE SEL signal from reaching an associated data storage device drive. A number of internal optional links and NAND gates on the circuit card can create further selectable operational features.

REFERENCES:
patent: 4734851 (1988-03-01), Director
patent: 4811293 (1989-03-01), Knothe et al.
patent: 5144660 (1992-09-01), Rose

Affiliated with

Also associated with

Rating

Hardware circuit for securing a computer against undesired write does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Hardware circuit for securing a computer against undesired write, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hardware circuit for securing a computer against undesired write will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1947766