These guys sell surplus and, thankfully, will sell parts in quantities that small users can buy.

I refer to long-past experience with Hamilton-Avnet, Arrow, Anthem (no longer with us), Future, whose salespeople happily take rejects from one mfg and sell them to another in order to keep their volumes up. They also grab the order for your 100 pieces per month and deliver them to megacorp down the street which consumes 10000 pieces per day so their need will be met, (we had that come up during the early '80's when DRAMs were in short supply and STC was shipping 288 pieces per board in 30 boards per hour) never mind that you'll go out of business because you can't fill your orders. Their salesmen aren't smart enough to know that 1K7 is not the same as 1K2. They certainly don't know that you can use 74AC573 in place of 74HC573 in a pinch. You've been to lunch with 'em, so you know they can't even order lunch.

This thread is about testing the 805x subsystem, though, and not about buying parts. If I see peculiar behavior in a "family-logic" component, I stick it in a tester before spending lots of time trying to figure out why it's odd. That takes, at most 5 minutes, and the tester is in the room next to most of the stock. I'd have to go there to get a replacement anyway.

However, what I'm seeing is that, just as in the case where the fellow wanted to use "old" parts to do something perfectly reasonable, at least in his mind, and quite achievable, he was immediately confronted with, "Why would you want to do that?" and, "You should use THIS part ..." rather than an answer to his question.

What I conclude is that nobody in this forum has ever bothered to generate a set of code that systematically checks for proper function of the MCU.

As for your remark about saving $0.17 on a $0.20 component, well, isn't that a worthwhile effort?

When I buy parts for use in my work, I often, very often, need fewer than a dozen. The cost of such purchases often exceeds the cost of the components, i.e. the labor involved in ordering, tracking, and paying for the parts is more than the price of the parts. I use two or three parts, then put the rest in stock. Well, I want to know, with confidence, that the parts I have in stock are all fully functional.

I remember that you once said that you didn't need to test LCD's beyond the functions that you use in your application. Well, that's probably true if all you care about is "getting them out the door" since that will suffice for a demonstration. If several functions fail, however, isn't the entire device broken? Would you ship a defective device in your product? If some of the bits don't fail until it's had a chance to warm up, aren't you concerned it will have some effect? Would you ship a product when the carry doesn't work just because you don't use it in the current code? What if the next field-fix requires it?

RE