Hardware

Motherboard Form Factors

Form Factor	Size (WxL)	Size (WxL) cm	Description
ATX	12" x 9.6"	30.5cm x 24.4cm	Standard size, widely used in mid to full-sized desktops. Supports multiple expansion slots.
Micro-ATX (mATX)	9.6" x 9.6"	24.4cm x 24.4cm	A smaller version of ATX. Fewer expansion slots but maintains compatibility with ATX cases.
Mini-ITX	6.7" x 6.7"	17cm x 17cm	Compact form factor, popular for small form factor (SFF) builds. Typically has one expansion slot.
Extended ATX	12" x 13"	30.5cm x 33cm	Larger than standard ATX. Used for high-end systems with multiple GPUs or extensive I/O.
Nano-ITX	4.7" x 4.7"	11.9cm x 11.9cm	Even smaller than Mini-ITX. Less common and used for specialized applications.
Pico-ITX	3.9" x 2.8"	9.9cm x 7.1cm	One of the smallest form factors. Limited expansion and I/O capabilities.
BTX	Varies	Varies	Designed as a successor to ATX but didn't gain widespread adoption. Focuses on improved cooling and layout.
FlexATX	9.0" x 7.5"	22.9cm x 19.1cm	A variation of ATX with a smaller size. Less common.
Mini-DTX	8.0" x 6.7"	20.3cm x 17cm	Slightly larger than Mini-ITX, allowing for an extra expansion slot.

Network

Standard	Speed	Description
Ethernet (10BASE-T)	10 Mbps	Early standard for wired LANs.
Ethernet (100BASE-TX/Fast Ethernet)	100 Mbps	Increased speed over original Ethernet.
Gigabit Ethernet (1000BASE-T)	1 Gbps	High-speed wired LANs, backbone for many networks.
10 Gigabit Ethernet	10 Gbps	Very high-speed wired LANs, used for data centers.
Wi-Fi 802.11a	Up to 54 Mbps	Operates in 5 GHz band, less interference than 2.4 GHz.
Wi-Fi 802.11b	Up to 11 Mbps	Early Wi-Fi standard, operates in 2.4 GHz band.
Wi-Fi 802.11g	Up to 54 Mbps	Improved speed over 802.11b, operates in 2.4 GHz band.
Wi-Fi 802.11n	Up to 600 Mbps	MIMO technology, operates in both 2.4 GHz and 5 GHz bands.
Wi-Fi 802.11ac (Wi-Fi 5)	Up to 3.5 Gbps	Faster speeds, operates mainly in 5 GHz band.
Wi-Fi 802.11ax (Wi-Fi 6)	Up to 9.6 Gbps	Improved efficiency, better in crowded areas.
LoRa	< 50 kbps	Long-range, low power consumption for IoT devices.
Bluetooth 4.2	Up to 1 Mbps	Low energy, suitable for many battery-powered devices.
Bluetooth 5	Up to 2 Mbps	Improved range and speed over Bluetooth 4.2.
5G NR	Up to 20 Gbps	High-speed mobile network, low latency, supports IoT.
4G LTE	Up to 1 Gbps	High-speed mobile network, widespread adoption.
3G UMTS	Up to 384 kbps	Early mobile broadband.
Zigbee	250 kbps (2.4 GHz)	Low power, mesh networking for home automation.
Z-Wave	40-100 kbps	Low latency, mesh networking primarily for home automation.
NFC	424 kbps	Short-range, often used for contactless payments.
Thread	250 kbps	Low-power, mesh networking for home IoT.

Storage

Floppy Disks

8-inch: 80 KB to 1.2 MB
5.25-inch: 110 KB to 1.2 MB
3.5-inch: 720 KB (DD) to 2.88 MB (ED)

Hard Disk Drives (HDDs)

1990s: 40 MB to 10 GB
2000s: 20 GB to 500 GB
2010s: 500 GB to 4 TB became common for consumer devices
2020s: 2 TB to 16 TB (and even larger capacities for enterprise solutions)

Solid-State Drives (SSDs)

Late 2000s: 32 GB to 256 GB
Early 2010s: 128 GB to 1 TB
Late 2010s: 256 GB to 4 TB became more standard for consumer devices
2020s: 512 GB to 8 TB (with enterprise solutions offering even larger capacities)

Optical Discs

CD-ROM: ~700 MB
DVD: 4.7 GB (single layer) to 8.5 GB (dual layer)
Blu-ray: 25 GB (single layer) to 50 GB (dual layer), with higher capacities like 100 GB for triple-layer discs

Flash Drives (USB Sticks)

Early 2000s: 32 MB to 512 MB
Late 2000s: 1 GB to 16 GB
2010s: 8 GB to 128 GB became common
2020s: 16 GB to 1 TB (though larger capacities like 2 TB exist, they're less common)

SD Cards

SD: 1 MB to 2 GB
SDHC: 4 GB to 32 GB
SDXC: 64 GB to 2 TB
SDUC: 2 TB to 128 TB (theoretical maximum)

Screen standards

Resolution

Standard Definitions (SD):

720 x 480 (DVD quality)
640 x 480 (VGA)

High Definitions (HD):

1280 x 720 (720p)
1920 x 1080 (1080p or Full HD)

Ultra High Definitions (UHD):

2560 x 1440 (2K or QHD/Quad HD)
3840 x 2160 (4K or UHD)
7680 x 4320 (8K or Super Hi-Vision)

Others:

1600 x 900 (HD+)
2048 x 1080 (DCI 2K)
4096 x 2160 (DCI 4K)

Mobile and Tablet Resolutions:

800 x 480 (WVGA)
1136 x 640 (iPhone 5/5S/5C)
1334 x 750 (iPhone 6/6S/7/8)
1920 x 1200 (WUXGA)
2048 x 1536 (iPad Retina)
2560 x 1600 (Nexus 10, QHD+)

Computer Monitors:

1024 x 768 (XGA)
1280 x 1024 (SXGA)
1440 x 900 (WXGA+)
1680 x 1050 (WSXGA+)
1920 x 1200 (WUXGA)

Pixels per Inch

To calculate Pixels per Inch:

screen PPI formula

For example, for a 5-inch screen with a resolution of 1920 x 1080:

screen PPI formula

So, the PPI would be approximately 440.58 for this screen.

Some other examples:

13.3" @ 1080p = 165.63 PPI
22" @ 1080p = 100.13 PPI
25" @ 1080p = 88.12 PPI
22" @ 1440p = 133.51 PPI
24" @ 1440p = 122.38 PPI
25" @ 1440p = 117.49 PPI
27" @ 1440p = 108.79 PPI
32" @ 1440p = 91.79 PPI
27" @ 4k = 163.18 PPI
36" @ 4k = 122.38 PPI
50" @ 4k = 88.12 PPI

Response Times

Display Monitors

TN (Twisted Nematic) panels: 1ms - 5ms
IPS (In-Plane Switching) panels: 4ms - 10ms
OLED panels: Typically under 1ms

Web Servers

Fast response: Under 200ms
Average response: 200ms - 500ms
Slow response: Over 500ms

Databases

In-memory databases (like Redis): Sub-millisecond to a few milliseconds
Traditional relational databases (like MySQL, PostgreSQL): Single-digit milliseconds for simple queries, but complex operations can take much longer

APIs (Application Programming Interfaces)

Fast response: Under 100ms
Average response: 100ms - 300ms
Slow response: Over 300ms

Immediate/Urgent: Within 1 hour or less
High priority: Within 4 hours
Medium priority: Within 24 hours
Low priority: Within 72 hours or more

Disk Access

NVMe SSDs: Typically under 0.1ms
SATA SSDs: Around 0.2ms - 0.5ms
HDDs: 5ms - 10ms (for 7200 RPM drives), 15ms - 20ms (for 5400 RPM drives)

Network Latency

Local Area Network (LAN): Under 1ms
Wide Area Network (WAN) or Internet: Varies widely based on distance, routing, and other factors. Can range from a few milliseconds to several hundred milliseconds.

Cloud Services

Content Delivery Networks (CDNs): Tens of milliseconds, depending on the user's proximity to the nearest edge location
Cloud storage (like AWS S3, Google Cloud Storage): Typically tens to hundreds of milliseconds, depending on the operation and network conditions