??? 07/23/09 14:35 Read: times |
#167748 - It could be quite straightforward Responding to: ???'s previous message |
using http://neil.franklin.ch/Info_Text...n_Set_8048 as a reference ...
If those ports were simply replaced by easily compatible hardware, all that would have to be done is the MOVD instructions ( I rememeber them as MOVP instructions, for some reason) which specifically "talk" to i8243's, and only that, could be replaced with an 805x macro. The result, then, could be complete transparency to the remainder of the firmware, I believe. The programmable logic, or whatever, could then be tailored to provide the appropriate port hardware needed by the system, and not necessarily synthesize, precisely, the function of the i8243. I doubt the cost of a small cpld in, say, TQFP64 would exceed the cost of a couple of 8243's, and one FPGA could provide all 240 of his desired I/Os, if that's what he really needs. RE |