I believe that at one time if you bought an 8087 FPU from IBM as a PC upgrade you got an 8088 with it. Apparently some early 8088s (which ended up in IBM PCs) had problems working with the 8087 (I can't remember the details), so they gave you a 'good' 8088 to install with the 8087 just in case you had a defective one in your machine -tony