< Do I not recall correctly that the 8088 was in fact half of a two chip < set and that the 8086 was 'self contained', and that IBM elected to not < the other half. < - don Huh? The 8088 is for all intents and purposes the same part as the 8086. the prformance hit for the 8bit vs 16 bit data bus averages around 20%. The reason the is the prefetch que is 6 bytes on the 86 and 4bytes on the 88 as a measure to "tune" it. The instruction sets are identical and the supporting chips are exactly the same (86 will need more bus buffers). Oh, and the FPU the 8087 worked with either part and sized it's bus accordingly. I've done designs using both and they can almost be drop in for each other (same for the 80188/186). Allison