Other makers of 80486-like CPUs Intel 80486

stmicroelectronics st st486dx2-40



umc green cpu u5sx

80486 compatible processors have been produced other companies such ibm, texas instruments, amd, cyrix, umc, , sgs thomson. clones (identical @ microarchitectural level), others clean room implementations of intel instruction-set. (ibm s multiple source requirement 1 of reasons behind x86-manufacturing since 80286.) 80486 was, however, covered many of intel s patents covering new r&d of prior 80386. intel , ibm have broad cross-licenses of these patents, , amd granted rights relevant patents in 1995 settlement of lawsuit between companies.

amd produced several clones of 80486 using 40 mhz bus (486dx-40, 486dx/2-80, , 486dx/4-120) had no equivalent available intel, part specified 90 mhz, using 30 mhz external clock, sold oems. fastest running 80486 cpu, am5x86, ran @ 133 mhz , released amd in 1995. 150 mhz , 160 mhz parts planned never officially released.

cyrix made variety of 80486-compatible processors, positioned @ cost-sensitive desktop , low-power (laptop) markets. unlike amd s 80486 clones, cyrix processors result of clean-room reverse-engineering. cyrix s offerings included 486dlc , 486slc, 2 hybrid chips plugged 386dx or sx sockets respectively, , offered 1 kb of cache (versus 8 kb then-current intel/amd parts). cyrix made real 80486 processors, plugged i486 s socket , offered 2 or 8 kb of cache. clock-for-clock, cyrix-made chips slower intel/amd equivalents, though later products 8 kb caches more competitive, if late market.

the motorola 68040 (e.g. used in macintosh quadra series), while not compatible 80486, positioned 80486 s equivalent in features , performance. clock-for-clock basis motorola 68040 outperform intel 80486 chip. however, 80486 had ability clocked faster without suffering overheating problems. motorola 68040 performance lagged behind later production 80486 systems.