The fx-7400GII is a fx-9860GII
without backlight, without USB-port, with a smaller LCD (visible diagonal
65mm) and a smaller flash-capacity (2MB).
It has 512k RAM, CPU 7355, a compatible LCD-chip. In fact the board-layout is nearly identical to that of the fx-9860GII. The fx-7400GII OS supports OS update procedures via the serial interface.
The OS is dramatically degraded. Though the hardware would support a 60 kB user memory, it is reduced to 20 kB by the OS.