MATSEC SEC Information Technology cheat sheet
MATSEC SEC Information Technology · Keep the key ideas within reach.
Information Technology - Core Concepts, Hardware, Software and Data
Data vs information: data are raw unprocessed facts (e.g. marks 45, 67, 89); information is data processed into a meaningful form (e.g. class average = 67%). Processing converts data into information; storage, retrieval and communication preserve it.
Hardware categories: input devices (keyboard, scanner, sensor), output devices (monitor, printer, actuator), processing (CPU), storage (HDD, SSD, optical, flash) and communication devices (NIC, router, modem).
CPU fetch–decode–execute cycle: fetch the instruction from memory using the program counter, decode it in the control unit, execute it in the ALU, then store the result. Clock speed (GHz) and core count affect throughput.
Memory hierarchy by speed and cost: CPU registers > cache > RAM > SSD/HDD > optical/tape. RAM is volatile (contents lost on power-off); ROM is non-volatile and holds firmware such as the BIOS/UEFI boot program.
Storage units: 1 byte = 8 bits; 1 KB = 1024 bytes; 1 MB = 1024 KB; 1 GB = 1024 MB; 1 TB = 1024 GB. File size = number of samples × size per sample (e.g. 3-minute stereo 44.1 kHz 16-bit audio ≈ 30 MB uncompressed).
Software types: system software (operating system, utilities, device drivers) manages hardware and provides a platform; application software (word processor, spreadsheet, browser) performs user tasks. The OS handles memory management, scheduling, file management and user interface.
File formats and compression: lossless compression (ZIP, PNG, FLAC) restores the original exactly; lossy compression (JPEG, MP3) discards data permanently for smaller files. Choose lossy for photos/audio distribution, lossless for text, code and archives.
Data validation vs verification: validation checks data is acceptable (range check, type check, presence check, format check, check digit); verification checks data was copied/entered correctly (double entry, visual check, parity). Validation cannot detect a plausible but wrong value.
Networks: LAN covers a small area (one building) and is usually owned; WAN spans large distances and uses third-party links. Topologies: star (central switch, single point of failure), bus (shared backbone), mesh (redundant paths). Bandwidth is capacity; latency is delay.