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Security Model
Is a statement that outlined the requirements necessary to properly support a certain security policy.
Computer Architecture
CPU - Central Processing Unit:
Is a microprocessor
Contains a control unit, an ALU / Arithmetic Logic Unit and primary storage.
Instructions and data are held in the primary storage unit needed by the CPU.
The primary storage is a temporary memory area to hold instructions that are to be interpreted by the CPU and used for data processing.
Buffer overflow - Data being processed is entered into the CPU in blocks at a time. If the software instructions do not properly set the boundaries for how much data can come in as a block, extra data can slip in and be executed.
Real storage - As instructions and data are processed, they are moved back to the system's memory space / real storage.
Memory:
RAM / Random Access Memory - Is a volatile memory, because when power is lost -> information is lost.
Types of ram:
- Static RAM - When it stores data, it stays there without the need of being continually refreshed.
- Dynamic RAM - Requires that that data held within it be periodically refreshed because the data dissipates and decays.
ROM / Read-only memory - Is a nonvolatile memory. Software that is stored within ROM is called firmware.
EPROM / Erasable and programmable read-only memory - Holds data that can be electrically erased or written to.
Cache memory:
Is a part of RAM that is used for high-speed writing and reading activities.
PLD - Programmable Logic Device:
An integrated circuit with connections or internal logic gates that can be changed through programming process.
Memory Mapping:
Real or primary memory - Memory directly addressable by the CPU and used for the storage of instructions and data associated with the program that is being executed.
Secondary memory - Is a slower memory (such as magnetic disks) that provides non-volatile storage.
Sequential memory - Memory from which information must be obtained by sequential searching from the beginning rather than directly accessing the location (magnetic tape, ...)
Virtual memory - Uses secondary memory in conjunction with primary memory to present a CPU with a larger, apparent address space of the real memory locations.
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