The parallel programing hardware for the 875x's was published in the datasheet. ISTR that it involved using a preprogrammed EPROM and some counters, or some such, which wasn't expensive or difficult at all, but then, again, one couldn't erase/program the internal program store. It was not done serially, though there's no reason it couldn't have been done so.

The 8031/2, IIRC, actually was an 8051/2 with a ROM present, which you could observe in operation, at least momentarily, if you tied nEA to Vcc. I don't know whether these were defective or simply overruns. However, if the O/P wishes to use his p8052 as an 8032, he can probably do so, as I pointed out before.

In order to program his external memory serially, he must simply introduce a program into his external memory, provided it's capable of managing whatever requirements that memory has, e.g. the lower portion BBRAM, where the serial programming code would reside, would have to be overwritten with code to be used once the programming is finished. This might simply be a move from, say, 0x200 to 0x0000 once the code is in place. The same might be done with FLASH memory. I'm partial to FRAM, as it's as fast as nearly any common SRAM and requires no sectoring and associated write timing. That's what I'd use in this sort of situation. It can be written at will without any setup just like SRAM, but retains its content if power is lost. All the usual caveats regarding power-down and power-up apply, of course.

RE