Hello, I am working with an unsupported bootloader and OS. With the on-board video, the bootloader works great (the OS is another story). I can use the serial port connection on UART1 as documented at https://www.udoo.org/docs-x86/Hardware_Reference/Pinout_Braswell.html with a USB-TTL connector to OS X with screen (115200 8 N 1). The Insyde splash screen and subsequent screen come up fast, with no delays (they display ahead of the video monitor). However, once the bootloader starts sending characters to the BIOS in teletype mode (int 0x10, ah = 0x0E, bx = 0x0001), the serial output slows to a crawl. The bootloader is configured for 9600 8 N 1 (ax = 0x00E3). I have not seen this discussed in the forums for x86. 1) Is there an incompatibility with teletype mode? 2) Is there a better way to write characters to the video screen than teletype mode? 3) Can the udoo x86 support higher serial port modes? If so, what is the configuration code for ax? Thanks!