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back2root:ibm-pc-ms-dos:hardware:cpu
CPU Characteristics / Determination
| 8088,80188,V20 | six byte prefetch queue, allows use of self modifying code to determine length of prefetch |
| 8086,80186,V30 | four byte prefetch queue, allows use of self modifying code to determine length of prefetch |
| 8088,8086,80188,81086,v20,v30 | Flag register bits 12 through 15 cannot be cleared |
| 8088,8086 | will shift left or right using all 8 bits of CL, if CL = 33, register is guaranteed to be cleared |
| 80188,80186,80286,80386 | will shift left or right using only lower 5 bits of CL. If CL = 32, the shift will not occur |
| 80286,80386 | earlier CPU's decremented SP before a PUSH SP, but 286+ pushes the value first then, decrements SP |
| 8088,8086 | non-zero multiplication result clears zero flag |
| V20,V30 | non-zero multiplication result does not clear zero flag, set ZF before multiply, and test after, if it's still set, then it's a V20, V30 |
| 80286 | allows setting of bit 15 of the flags register |
| 80386 | allows setting of bits 12 through 14 of flags register |
back2root/ibm-pc-ms-dos/hardware/cpu.txt · Dernière modification : 2023/02/24 14:16 de frater
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