intel 8086 and compatibles -------------------------- this info is here, to list and give some remarks on all 8086 compatible processors excellent info in Hamarsoft's 86BUGS list (also distributed in ralf browns interrupt list) 8086/8088 --------- 20 bit address bus, 16 bit data bus and registers many 8080 assembler sources should be compilable/reusable 8086 ---- 6 bytes prefetch queue 8088 ---- 8086 with 8 bit data bus, prefetch queue only 4 byte, and refilled when 1 byte empty early 8086/8088 revisions bug ----------------------------- (copyright 1978 on package) mov sreg, doesnot disable until next operation is executed 8086/8088 --------- "mov cs, " causes unconditional jump! 0xd6 is salc (sbb al,al) as all other intel x86-16 and -32 cpus 80C86/80C88 ----------- "mov cs, " ignored 80186/80188 ----------- integrated pic, timer and dmac entirely incompatible with 8259, 825[3,4] and 82[3,5]7 additional instructions #BR/bound/int 5, #UD/illegal instruction/int 6, #NM/coprocessor unavailable/int 7 support "mov cs, " ignored (likely causes int 6) shift count anded with 0x1f 80188 ----- 8bit data bus NEC series ---------- 80186 instruction set, additional nec instructions although it is based on 80186 instruction set, some behaviours follow 8086 8080 emulation mode "mov cs, " ignored shift count not anded (acts like 8086) 0xd6 is xlat alias NEC 70116 (V30) --------------- 8086 pin compatible NEC 70108 (V20) --------------- 8088 pinout NEC V30MX --------- on die ems hardware 24 bit address but for ems memory!? no 8080 emulation mode NEC V40 ------- pinout, integrated peripherals 8259,54,37 clones at nonpc compatible addresses NEC V50 ------- pinout, integrated peripherals as v40 NEC V33? -------- speed optimized V30? NEC V25/V35? ------------ NEC V25+/V35+? -------------- NEC V60/V70 ----------- risc (misc/delux) like instruction set v30? emulation mode (without 8080 emulation mode) 80286 ----- 80186 with additional instructions but no peripherals 24 bit address bus, protected mode selector/descriptor 80386 and later --------------- not covered here 8087/80287/80387/80387sx ------------------------ mathematical coprocessors weitek, iit variants in 80486 coprocessor integrated (except 80486sx and several clones) 80487: 80486 with other pinout