The CNC 88 is the original control version and had a processor of only 25 BPS where as the CNC 88HS controller started at 72 BPS and is now at 250 PBS processing speed.
The system in the machine you are looking at may have been updated. Look at the card 1400 in slot #5 in the card cage in the rear of the machine. If it is a 1400-0 0r 1400-1 the you have the 25 and if it is 1400-2 then you have the 72. anything 1400-4 and beyond will be 150.
Hope that helps.