BISER-6 is apparently the newest digital computer subsystem which is used for Russian spacecraft (Proton-M, Angara, TSYKLON-3). It is based on subsystem developed for Zenit rockets and Fregat boosterÅ¡during 1980s. 32-bit architecture compatible with Ã¥Ã³ Ã¼Ã·Ã (clone of IBM mainframes), 8 Mhz clock. This isn't so bad, currently the most popular western CPU for space applications is RAD6000 CPU, which runs up to 20 Mhz. Where BISER-6 really lacks is the amount of RAM: 224 Kb compared to 128 MB on RAD6000SC.