Technology: Data Representation, Systems, and Networks
Domain scope
The Technology domain of the PhilNITS Fundamental Engineer (FE) examination tests whether you can trace how data is represented, processed, stored, and transmitted, and whether you can apply standard algorithms, database rules, and network rules to small concrete cases. Items are usually short calculations or single-statement judgments rather than essay prompts, so precision on definitions and formulas matters more than breadth.
Core rules to know
- Data representation: 8-bit signed integers use two's complement; the range is -128 to +127. Negation is invert-all-bits then add 1. Overflow occurs when the sign of the result contradicts the operands.
- CPU and memory: cache reduces average access time; hit ratio and miss penalty determine performance. Pipelining improves throughput, not the latency of a single instruction.
- OS: scheduling policies (FCFS, SJF, round robin), virtual memory paging, and process states.
- Databases: normalization to 3NF removes partial and transitive dependencies; ACID properties protect transactions.
- Networks: OSI and TCP/IP layering, IPv4 subnetting, and common port numbers.
- Security: confidentiality, integrity, availability; symmetric versus public-key cryptography.
Worked example
Represent -5 in 8-bit two's complement. Write +5 as 0000 0101. Invert the bits: 1111 1010. Add 1: 1111 1011. So -5 is 1111 1011 (FB in hexadecimal). Check: the leading bit is 1, so the value is negative; applying the same invert-and-add-one gives 0000 0100 + 1 = 0000 0101 = 5, confirming magnitude 5.
Traps
- Stopping after inversion and forgetting the +1.
- Reading 1111 1011 as 251 when the question specifies a signed integer.
- Confusing cache hit ratio with hit time.
- Counting all addresses in a subnet as usable hosts without subtracting the network and broadcast addresses.