The Master Boot Record (MBR) partitioning scheme has been with us since the invention of the PC. While it has many great qualities, it also imposes limitations on current hardware. For example, it limits the size of block addresses to 32 bits and four partitions, each with a maximum capacity of 2 TBytes. This can get even messier thanks to the limitation of Windows which, by default, creates two partitions when formatting a system.
Later updates have removed those limitations, sort of. For example, in the mid-1990s, Intel developed the Extensible Firmware Interface which was later integrated into the Unified EFI specification owned by UEFI Forum. UEFI provided the ability to use GUID partition table (GPT) which increases the block address size to 64 bits, and also raises the default partition limit to 128. This takes the maximum disk size to 8 Zbytes.
Such 鈥渁dvances鈥 are common to the embedded systems market where technology waves typically follow new technology (aka microprocessor) developments. In many cases, new generations of embedded computers aren鈥檛 much more than swapping out a newer, faster microprocessor.
And because these embedded systems often don鈥檛 require the larger storage space of PCs or servers, or even some consumer electronics, it鈥檚 fairly common to find applications still built around an MBR formatted system. This is especially true in applications where any changes are frowned upon and require thousands of dollars in testing and re-certifications. Medical diagnostics and even some large-scale manufacturing equipment represent perfect examples.
In practice, if you鈥檙e designing custom splash screens for embedded devices that happen to be running Windows 10, you still have the ability to boot in legacy mode. However, that splash screen will only be available while the BIOS is loading. It then goes to the standard Windows loading screen. With UEFI and a GPT drive, the API can provide a smooth transition from the UEFI to Windows, while maintaining the custom screen for the user.
On top of the re-certification issue, some of these applications simply don鈥檛 have the budget for a redesign, and frankly, the 鈥渙ld way鈥 works just fine. So there鈥檚 no need to redefine the root file system and the platforms to advance from one generation to the next. Hence, it鈥檚 not that unusual for 91大神 to run across a client still using legacy MBR-formatted boot media.
To that end, it behooves us at 91大神 to support whatever configuration our clients might require, from legacy BIOS with MBR, to UEFI with legacy boot, to UEFI with GPT boot. For example, one platform we make available that can be configured specifically for the client鈥檚 needs is the PPM-C407 single-board computer (SBC) that fits the PC104-Plus form factor.
The is designed with Intel鈥檚 E3800 family of Atom processors, which lets the system developer choose between a low-power single-core processor and higher-performing dual- or quad-core solutions. Features include two independent displays, a Gbit Ethernet controller, four serial ports, and four USB 2.0 ports. Designed for harsh environments and reliability, it includes 4 Gbytes of soldered DDR3 DRAM for added shock and vibration resistance with a fanless operating temperature range from -40掳C to +85掳C.