CompactFlash vs. SD Bus Interfaces
Comparing 2 standards across 14 specifications. 14 key differences identified.
CompactFlash (CF) is the pioneering solid-state removable memory card standard introduced by SanDisk in 1994 and maintained by the CompactFlash Association (CFA). Based on a 50-pin Parallel ATA (PATA / IDE) interface, it dominated professional DSLR photography and industrial computing for two decades, scaling through CF+ specifications up to UDMA 7 (167 MB/s).
SD Bus Interfaces define the physical and electrical signaling architectures through which SD and microSD cards transfer data with host controllers. Spanning legacy Default/High Speed, Ultra High Speed tiers (UHS-I up to 104 MB/s, UHS-II up to 312 MB/s, UHS-III up to 624 MB/s), and PCIe/NVMe-based SD Express (up to 3,940 MB/s).
Specification Comparison Table
14 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Body
|
CompactFlash Association (CFA) | — |
|
Introduction Year
|
1994 (SanDisk) | — |
|
Physical Dimensions
|
36.4 mm × 42.8 mm × 3.3 mm (Type I) / 5.0 mm (Type II) | — |
|
Physical Connector Form Factor
|
50-pin female socket receptacle (2 rows of 25 pins on 1.27 mm pitch) | — |
|
Interface Protocol
|
Parallel ATA (PATA) / True IDE Mode / PCMCIA Memory Mode | — |
|
Max Bus Speed Tier
|
UDMA 7 (167 MB/s @ 133 MHz PATA clock in CF 6.0) | — |
|
Operating Voltages
|
Dual voltage: 3.3V (low power) or 5.0V (legacy standard) | — |
|
Video Performance Guarantee
|
VPG-20 (20 MB/s) / VPG-65 (65 MB/s sustained write for Full HD / 4K) | — |
|
Default Speed (DS) / High Speed (HS)
|
— | 12.5 MB/s (25 MHz @ 3.3V) / 25 MB/s (50 MHz @ 3.3V) |
|
UHS-I (SD 3.01)
|
— | SDR12 (12.5 MB/s), SDR25 (25 MB/s), SDR50 (50 MB/s), DDR50 (50 MB/s), SDR104 (104 MB/s @ 208 MHz 1.8V) |
|
UHS-II (SD 4.0)
|
— | 156 MB/s (Full Duplex) / 312 MB/s (Half Duplex) via 2nd pin row LVDS (0.26V) |
|
UHS-III (SD 6.0)
|
— | 312 MB/s (Full Duplex) / 624 MB/s (Full Duplex dual-lane LVDS) |
|
SD Express (SD 7.0 / 8.0)
|
— | 985 MB/s (PCIe 3.0 x1), 1970 MB/s (PCIe 4.0 x1 / 3.0 x2), up to 3940 MB/s (PCIe 4.0 x2) |
|
SD Express Protocol Stack
|
— | PCI Express (PCIe) + NVM Express (NVMe v1.3/1.4) over SD pins |