| ??? 07/07/10 20:36 Read: times |
#177141 - Sometimes it is easy to justify, sometimes not Responding to: ???'s previous message |
Andy Neil said:
If the goal was set on the basis that the parts are "free", that may need to be reviewed in the light of the fact that other things must be paid for in order to be able to use them. Very true! Often devices will be obsoleted because it is less costly to implement newer ones for the same purpose. eg, if you offered to give me your car for free, that might initially seem like a great deal - until you consider the cost of getting it over here!
And, even then, I'd be left with a car with the steering wheel on the wrong side and, possibly, difficult to get spares... Again, very true. It's important to know precisely what is involved in implementing a plan before starting to do so. So, even though the car itself is free, it might not turn out to be such a good deal.
Unless I specifically wanted your particular car! It does depend greatly on how the decision was made, to implement a circuit with "retired" parts. The question is multi-faceted, in that one must first determine what's required, whether the on-hand parts are healthy, what the requirements such as power will be, and what materials not yet on hand are required. This is particularly true if one wishes to use programmable parts in that mode. The 8755, for example, is an albatross if one wants just to use it as an I/O device, since 8255 would work just as well, though differently. If, however, there were usable 8755's and a programmer on hand, and no 8255's on hand, well ... RE |
