Thanks to the Super PC/Turbo XT BIOS 3.1 Retro Theory now has 736 Kb of RAM under msdos, super fast booting compared to the stock BIOS/ROS. Mem check is skipped, parity checking had to be altered, and CGA 80Col is hardcoded for now.
He had to modify the source code for testing the Nec V30 processor which is on the PPC 512. This stock new BIOS works well on an Amstrad PC 1640.
The additionnal RAM comes of course from an ISA board.