In computer hardware specifications, the printing speed of a laser printer is usually measured in:

Introduction / Context:
This computer awareness question examines your understanding of how laser printer performance is specified. When buying or comparing printers, you will often see speed and quality mentioned using standard units. Knowing what PPM, CPM, LPM, and DPI stand for helps you interpret these specifications correctly and answer related exam questions in general knowledge or computer sections.

Given Data / Assumptions:

• The question focuses on printer speed, not print quality or resolution.
• Options include PPM, CPM, LPM, and DPI, each used in different contexts.
• Basic familiarity with printing technology and computer hardware terms is assumed.

Concept / Approach:
Modern laser printers typically have their speed rated in pages per minute (PPM). This value indicates how many standard pages the printer can output each minute under specified conditions, such as black and white text printing. Characters per minute (CPM) was more common for older impact printers like dot matrix printers, where each character was printed separately. Lines per minute (LPM) is used mainly for line printers that print whole lines at once in large computing environments. Dots per inch (DPI) is not a speed measure; it describes resolution, or how many dots the printer can place in a one inch line, affecting print sharpness and detail, not how fast pages are printed. Therefore, the correct unit for laser printer speed is PPM.

Step-by-Step Solution:

Verification / Alternative check:
Looking at typical laser printer specifications, you will see entries like 20 PPM, 30 PPM, or 40 PPM for black and white printing, and sometimes separate speeds for colour pages. DPI values such as 600 DPI or 1200 DPI appear in a different part of the specification under resolution. Manuals for dot matrix printers, on the other hand, often mention speeds such as 300 characters per second or characters per minute, and some enterprise line printers specify lines per minute. These consistent patterns confirm that for laser printers, pages per minute is the standard speed unit, supporting option A as the correct answer.

Why Other Options Are Wrong:

CPM, meaning characters per minute used for older impact printers, is wrong here because laser printers are rated primarily by page output, not characters.

LPM, meaning lines per minute mainly for line printers, is incorrect because it is used in specific high volume printing environments, not typically for office laser printers.

DPI, meaning dots per inch describing print resolution, is wrong as a speed measure; DPI tells you about how detailed the print can be, not how fast the printer operates.

Common Pitfalls:
Students often confuse DPI with speed because both appear in printer specifications and they may choose DPI simply because it looks more technical. Another pitfall is not remembering which older units applied to impact printers. To avoid these errors, connect speed with how many pages are printed per minute. Remember that laser printer speed is usually measured in PPM (pages per minute), while DPI refers to print quality, and CPM or LPM apply to older or specialised printing technologies.