Gecko's CPU Library

DEC Alpha 21064A (EV45) and 21066A (LCA45) processors

Introduction: November 1994

21064A (EV45) was announced at a Microprocessor Forum in October of 1993. It was a modified EV4 manufactured with a proprietary 4-layer 0.5µ CMOS5 process. 21066A (LCA45) was presented at a COMDEX in November of 1994. It was modified almost exactly the same way as EV4 was towards EV45 in means of technological process and core internals. To mention, DEC's marketing people developed a habit to add a letter to a processor's model name after a redesign towards a more advanced process. Both cores of EV45 and LCA45 were changed not so much: I-cache and D-cache of EV45 were doubled in size (16KB I-cache + 16KB D-cache) and their data and tag fields gained a parity bit each, branch history fields of I-cache were expanded to 16 bits, D-cache became 2-way set associative and 1-bit byte parity mode was added to those existing integrity modes of the system data bus. In addition, both EV45 and LCA45 were awarded with a modified F-box (division optimisation: EV4 could execute a floating-point division instruction in 34 cycles for single-precision operands and in 63 cycles for double-precision operands with no dependence upon operands' values; EV45 could do the same thing in 19 to 34 cycles for single-precision operands and in 29 to 63 cycles for double-precision operands with dependence upon operands' values). LCA45 was also manufactured by Mitsubishi. Both dies decreased in size to 164mm² for EV45 and to 161mm² for LCA45. Transistors' count increased to 2.85 mln. for EV45 and remained 1.75 mln. for LCA45. Finally, power consumption per cycle decreased for both processors, though power supply voltage didn't change from 3.3V. Core frequencies of 21064A ranged from 200MHz to 300MHz (TDP from 24W to 36W), of 21066A from 166MHz to 233MHz.