Notes, summaries, assignments, exams, and exercises for Computer science for University

CISC: Complex Instruction Set Computer

The Complex Instruction Set Computer (CISC) architecture packs more complex instructions into the processor. Some instructions might perform several tasks in one go. This design reduces the number of instructions a programmer needs to write but makes the CPU's internal logic more complicated and potentially slower for some tasks.

• Think: “Do more, but it might take longer.”

CISC is commonly found in x86 architectures (e.g., typical laptops or desktops), where compatibility and code density often matter more than raw efficiency.

RISC vs. CISC: Architectural Approaches

Both RISC (Reduced Instruction Set Computer) and CISC architectures aim to solve the same problem—efficient program execution—but they...

Von Neumann Architecture Fundamentals

The Von Neumann Architecture is a foundational computer architecture model where the Central Processing Unit (CPU), memory, and input/output devices share a single communication pathway—the system bus.

This design is characterized by using the same memory space for both instructions (programs) and data, often referred to as the stored-program concept.

We can examine how instructions flow through this architecture and how it compares to other models, such as the Harvard Architecture.

Essential Components for Instruction Execution

Here is a breakdown of three key registers—the Program Counter (PC), Instruction Register (IR), and Memory Address Register (MAR)—all essential for executing instructions in a...

Lecture 2: Dynamic Dispatch and Interfaces

• Dynamic Dispatch: The process of selecting which implementation of a polymorphic operation to call at runtime.
• Interface: Calling a method that is not in the interface will cause a compilation error.

Lecture 3: N/A

Lecture 4: Method Contracts, Exceptions, and Unit Testing

• Method Contract: Should define pre/post conditions and exceptional behavior. The client is to blame if the precondition is not met, and the service is to blame if the postcondition is not met. Exceptional behavior specifies what the code will do if a precondition is violated.
• Exception: Runtime exception (unchecked) and IO exception (checked). The IO exception must be caught; otherwise, the code won't compile.
• Unit Test: Test boundary

AI Meets AI: Leveraging Query Executions to Improve Index Recommendations

How artificial intelligence (AI) can benefit automated indexing (AI)?: Comparing the execution cost of two plans (different index configurations of same query) is key for index tuning. Instead of using optimizer’s estimates for such comparison, formulating it as a classification task in machine learning results in significantly higher accuracy.

MOTIVATION:

• Being able to fully automate index recommendation and implementation is a significant value-add for improving query execution cost.
• Requirement: creating or dropping indexes should not cause significant query performance regressions - users enforce a no query regression constraint.
• Using the optimizer’s estimates to

Runtime Memory Organization

The organization of memory at runtime depends on the type of language (declarative, imperative), the compiler, and the operating system.

General Structure of Programming Languages

When you run a program, the OS loader allocates the required amount of memory and loads the code to be executed (stored in a file) into the code area.

The OS should detect collisions between the stack and the heap. In these cases, the program may abort, or the amount of allocated memory may be increased.

In memory paging systems, the above scheme can be fragmented and scattered between real memory and the virtual memory system.

Any reference to a storage location within the code should be relative to the position assigned to the process by the...

Functions in C

Void functions provide a way to emulate what are called procedures in other languages (e.g., PASCAL). They are used when it is not required to return a value. Here is an example that prints the squares of certain numbers:

void square ()
{
int count;

for (counter = 1; count < 10; counter++)
printf ("%d\n", counter * counter);
}

main ()
{
square ();
}

Input and Output Parameters

To use parameters in/out, the formal parameter must be preceded by the ampersand symbol (&), and the current parameter must be a variable (not an expression). Input/output parameters are used when you want a procedure to change the contents of the current variable. The fact that these parameters are explicitly defined as variables makes the programmer aware of...

Digital Awareness

When you want to receive digital information from the outside: The business card input channels are available, usually in groups of 8 bits, to which binary information is assigned by a program. These can be assigned to an internal variable state of a byte by a reading instruction that may have a port. There can be one or more bytes of input, assigning each an address.

Analog Outputs

To send analog control signals to the outside, the tallies have one or more channels of output through their respective A/D converters. A 1V analog converter generates a constant proportional to the numerical value of the digital data that it has on its input lines. Internally, they have a 5V memory. Different voltage ranges can be obtained using...

funcition min-max(pos,out-eval,out-best_move,in-whomoves,in-max_level){max=-?;min=?;best_move=0;if(level==0){evaluation=eval_(pos);best_move=0; return;}else{foi(i=0;i<num_succ(i);++i){succi=succesor(i);if(whomoves=='max'){min-max(succi,evaluation,best_move,'min', max_level-1);if(evaluation>max){max=evaluation; best_move=i;}}else{min-max(succi,evaluation,best_move,'max', max_level-1);}if(evaluation<min){min=evaluation;best_move=i;}}}}

funcition ??(pos,level,quien_juega,*eval,mejor_move,?,?){if(terminal(pos)||(level==0){*eval=eval(pos);return;}n_succ= num_succ(pos);for(i=0;i<n_succ;++i{if(quien_juega=='max'){succi=succesor(pos,i);??(succi,level-1,'min',evali, mejor_movi,?,?);if(evali>?){?=evali;*eval=?; *mejor_move=i;}if(?>?)...

Features of an OPAC

OPAC (Online Public Access Catalogue):

Core Features of an OPAC

1. Advanced Search Capabilities

• Multi-Field Searching: Allows retrieval using specific metadata like Author, Title, ISBN, Subject, and Call Number.
• Boolean & Query Refinement: Supports Boolean operators (AND, OR, NOT), wildcard truncation, and phrase searching to narrow down results.

2. Real-Time Status & Location Tracking

• Circulation Status: Displays live item availability (e.g., Available, Checked Out, On Hold, Lost).
• Dynamic Location: Pinpoints the exact physical location, including the specific collection (e.g., Reference, Stack) and the Call Number/Shelf Mark.

3. Patron Self-Service (My Account)

• Circulation Control: Enables users to log in to renew issued