Types of Memory Cards: Technical Comparison, Performance Classes, and Usage Across Devices – Bison Knowledgebase

Types of Memory Cards: Technical Comparison, Performance Classes, and Usage Across Devices

📅 04 Jan 2026 📂 General 👁 12 views

Memory cards are removable flash storage devices used across a wide range of digital equipment such as smartphones, cameras, drones, dashcams, industrial devices, and embedded systems. Selecting the correct memory card is not only about capacity, but also about form factor compatibility, bus interface, speed class, endurance, and workload type.

This knowledge base article provides a technical and practical explanation of memory card types, their performance metrics, and recommended usage across different segments like mobiles, consumer devices, professional cameras, and enterprise/industrial use.

2. What Is a Memory Card (Technical Overview)

A memory card is a NAND flash-based non-volatile storage device that consists of:

NAND flash memory cells (SLC / MLC / TLC / QLC)
A controller (wear leveling, error correction, bad block management)
Interface bus (UHS, PCIe, etc.)
Firmware (defines speed, reliability, and compatibility)

Key Characteristics

Non-volatile (data retained without power)
Limited write cycles (depends on NAND type)
Performance depends on controller + interface
Susceptible to corruption if removed improperly

3. Physical Types of Memory Cards (Form Factor)

3.1 microSD (Most Common – Mobile & IoT)

Physical Size: 15 × 11 × 1 mm

Used In:

Smartphones
Tablets
Action cameras
Dashcams
Drones
IoT devices
SBCs (Raspberry Pi)

Variants by Capacity:

microSD: up to 2 GB
microSDHC: 4–32 GB
microSDXC: 64 GB–2 TB
microSDUC: up to 128 TB (theoretical)

3.2 SD Card (Standard Size)

Physical Size: 32 × 24 × 2.1 mm

Used In:

Digital cameras
Mirrorless cameras
Camcorders
Audio recorders
Laptops (card readers)

Variants:

SD
SDHC
SDXC
SDUC

3.3 CompactFlash (CF) – Legacy Professional

Used In:

Older professional DSLRs
Industrial imaging systems

Characteristics:

Parallel ATA interface
Very durable
Largely replaced by faster standards

3.4 CFexpress (Modern Professional Standard)

Used In:

High-end mirrorless cameras
Professional video cameras
8K RAW recording systems

Types:

Type A (small, PCIe x1)
Type B (common, PCIe x2)
Type C (large, PCIe x4)

Technology:

PCIe + NVMe protocol (similar to SSDs)

3.5 XQD Cards

Used In:

Certain professional cameras (transition standard)

Note: Mostly replaced by CFexpress Type B

4. Speed Classes Explained (Critical Section)

4.1 Speed Rating Hierarchy

Device Requirement → Minimum Sustained Write Speed

A. Speed Class (Legacy)

Class	Min Write Speed
Class 2	2 MB/s
Class 4	4 MB/s
Class 6	6 MB/s
Class 10	10 MB/s

B. UHS Speed Class

UHS Class	Min Write Speed	Typical Use
U1	10 MB/s	Full HD video
U3	30 MB/s	4K video

C. Video Speed Class (Most Important for Cameras)

Class	Sustained Write	Usage
V10	10 MB/s	HD
V30	30 MB/s	4K
V60	60 MB/s	6K
V90	90 MB/s	8K RAW

D. Application Performance Class (Mobile Devices)

Class	Read IOPS	Write IOPS	Usage
A1	1500	500	Apps on Android
A2	4000	2000	Heavy apps & games

5. Interface Bus and Performance Limits

SD / microSD Bus Types

Bus	Max Speed
UHS-I	104 MB/s
UHS-II	312 MB/s
UHS-III	624 MB/s
SD Express	985+ MB/s

CFexpress

PCIe Gen 3 / Gen 4
1,000–4,000 MB/s (model dependent)

6. Usage by Segment (Practical Mapping)

6.1 Mobile Phones & Tablets

Recommended:

microSDXC
A2 + UHS-I
128–512 GB

Reason:

App loading performance
Smooth 4K recording
Faster random I/O

6.2 CCTV, Dashcams & Continuous Recording

Recommended:

High Endurance microSD
V30
SLC or pseudo-SLC NAND

Reason:

Designed for continuous overwrite
Higher TBW (Total Bytes Written)

6.3 Consumer Photography (DSLR / Mirrorless)

Recommended:

SDXC UHS-II
V60 or V90 (depending on burst & video)

Reason:

Faster buffer clearing
Reliable RAW shooting

6.4 Professional Video & Cinematography

Recommended:

CFexpress Type B
Sustained write ≥ 800 MB/s

Reason:

6K / 8K RAW
High bitrate codecs

6.5 Industrial & Embedded Systems

Recommended:

Industrial-grade SD / microSD
Wide temperature tolerance
Power-loss protection

7. Step-by-Step: Choosing the Right Memory Card

Step 1: Check Device Compatibility

Form factor (SD / microSD / CFexpress)
Maximum supported capacity
Supported bus (UHS-I vs UHS-II)

Step 2: Identify Workload

App storage
Burst photography
Continuous recording
High-bitrate video

Step 3: Select Speed Class

Apps → A2
4K video → V30 minimum
Professional video → V60 / V90

Step 4: Choose Endurance Level

Surveillance → High Endurance
Normal usage → Standard TLC

8. Common Issues and Fixes

Issue: Card Is Slow

Causes:

Card reader bottleneck
Fake card
Wrong speed class

Fix:

Test using:


h2testw (Windows)
f3write / f3read (Linux)

Issue: Card Corruption

Causes:

Unsafe removal
Power loss
Low-quality NAND

Fix:

Always eject properly
Use branded cards
Replace if reoccurring

Issue: Card Not Detected

Causes:

Unsupported capacity
File system mismatch (exFAT/FAT32)

Fix:

Format using device
Use official SD formatter

9. Security Considerations

Memory cards do not encrypt data by default
Easily removable → data leakage risk
Malware can spread via infected cards

Recommendations:

Use device-level encryption
Avoid using unknown cards
Physically destroy sensitive cards when retired

10. Best Practices

Match card speed to device capability
Avoid mixing cheap cards in professional workflows
Replace cards after heavy usage cycles
Keep backups (cards are not archives)
Label cards by usage and age

11. Conclusion

Memory cards vary significantly in form factor, interface, speed, endurance, and reliability. Selecting the wrong card can result in data loss, dropped frames, slow performance, or device malfunction. By understanding speed classes, bus standards, and workload requirements, users can make informed decisions for mobiles, cameras, and professional systems.

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Types of Memory Cards: Technical Comparison, Performance Classes, and Usage Across Devices

2. What Is a Memory Card (Technical Overview)

Key Characteristics

3. Physical Types of Memory Cards (Form Factor)

3.1 microSD (Most Common – Mobile & IoT)

3.2 SD Card (Standard Size)

3.3 CompactFlash (CF) – Legacy Professional

3.4 CFexpress (Modern Professional Standard)

3.5 XQD Cards

4. Speed Classes Explained (Critical Section)

4.1 Speed Rating Hierarchy

A. Speed Class (Legacy)

B. UHS Speed Class

C. Video Speed Class (Most Important for Cameras)

D. Application Performance Class (Mobile Devices)

5. Interface Bus and Performance Limits

SD / microSD Bus Types

CFexpress

6. Usage by Segment (Practical Mapping)

6.1 Mobile Phones & Tablets

6.2 CCTV, Dashcams & Continuous Recording

6.3 Consumer Photography (DSLR / Mirrorless)

6.4 Professional Video & Cinematography

6.5 Industrial & Embedded Systems

7. Step-by-Step: Choosing the Right Memory Card

Step 1: Check Device Compatibility

Step 2: Identify Workload

Step 3: Select Speed Class

Step 4: Choose Endurance Level

8. Common Issues and Fixes

Issue: Card Is Slow

Issue: Card Corruption

Issue: Card Not Detected

9. Security Considerations

10. Best Practices

11. Conclusion

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