The AT68166H MCM incorporates four 4Mbit AT60142H SRAM dice. It can be organized as either one bank of 512Kx8, two banks of 512Kx16 or four banks of 512Kx8. It combines rad-hard capabilities, a latch-up threshold of 80MeV.cm/mg, a Multiple Bit Upset immunity and a total dose tolerance of 300Krads, with a fast access time. The MCM packaging technology allows a reduction of the PCB area by 50% with a weight savings of 75% compared to four 4Mbit packages. Thanks to the small size of the 4Mbit SRAM die, Atmel has been able to accommodate the assembly of the four dice on one side of the package which facilitates the power dissipation.