I normally advocate for letting the experimenter do what he wants, regardless of how inelegant it may be. In this case, however, I'd surely like to know why, exactly, you want to do this? Do you have a specific goal?

The 8048 had facilities for single-stepping through code, that was quite different from what has to be done with 805x-core processors, generally speaking. What's more, the 8243 was designed for use with the 8048 family, including the 8035 romless version, while the 805x-family has no features to support the 8243 at all. There's considerably more involved than just translating the object code. Making the 8243 work with the 805x core is not a simple undertaking and I'm not at all certain what purpose it might serve. If you want, simply, to use the 805x-core CPU, e.g. 8031, with external ROM, and RAM for external program store, and to display what's going on in the system using 7-segment LED's, that's all possible. Using the 8243 is less easy than any of those processes.



I believe you'll find driving the 7-segment LED displays much easier without the 8243 than with it. Since the 8243 presents a considerable burden to drive the displays, I'd suggest you consider using a character LCD module e.g. the ones interfaced via the HD44780 LCD controller or something similar as a display, and look at the possibilities offered via the LCD tutorials on this website. Please be a bit clearer about what the function of the 8243's is, and perhaps someone can provide a more convenient means of providing the function you desire.





As you know, P4-P7 are 4-bit ports specifically provided by the 8243 hardware and the specifics of the i/o expander interface instructions in the 8048 instruction set. There is no equivalent hardware for the 805x-core, hence, there are no equivalent instructions in the 805x instruction set. That is not to say it is impossible to do what you want, but you surely will be disappointed with the result, considering the amount of effort that is required.

RE