Again, focusing on what he originally said he wanted to do ... namely to make his P8052 work, obviously with external memory, since internal memory is of no use ... I think you may be "barking up the wrong tree."

First of all, if he correctly attaches an oscillator, as this particular MCU doesn't have an RC oscillator, or a crystal and a couple of cap's in order to get it to "run." Now, with nEA tied high, the MCU will attempt to execute the code in its program store, though that's unknown to us. It will, however, allow the regular occurrence of ALE to be monitored, along with the operation of the oscillator.

If, OTOH, he attaches an R-pack or an 8-bit buffer, e.g. '74xx245, to P0, with nPSEN enabling it as input as well as buffering nPSEN and thereby driving all the P0 inputs down, and with nEA tied low, the MCU will attempt to execute what it reads from external memory, which is NOP's. That will enable him to verify that the address buses and data bus are functioning properly. I think that's quite a bit, considering that he's then not had to program anything.

I realize that this is a fine point, but he already knows how to program a PC, but has no experience with MCU's. This will give him experience with MCU's that a larger portion of the newbies we encounter on this forum haven't yet had.

Don't you think that's worth a look? After doing this, perhaps a couple of hours' work, he'll have had experience that many of the students we see here will NEVER have, because they don't have access to a meters, 'scope, etc.

RE