The P8052 didn't have any EPROM. There was a P8652 that was OTP, but, being in the plastic package, it couldn't be erased in any sense.


Yes, I have to agree, since that's what I previously said.


Internal flash or otherwise reprogrammable program store is not a factor here. External flash is probably not a good choice either, as it requires intelligence to program it. EPROM is dumber, hence easier to program, particularly with small parts. FRAM is easier yet, the memories can be quite large. Though they're not as large, BBRAM's are pretty easy, too. The fact is, we don't know what hardware the O/P has at his disposal. He could have equipment available in a lab at school, or with a friend, or whatever.


I agree. That's why I mentioned the BBRAM or FRAM. Those require no programmer. If the nEA line were then tied low, the chip would attempt to use only external program store, enabled by nPSEN, and, with proper hardware design, (not rocket science, as it requires only that nRD, nWR, and nPS be negative NOR'd to produce a negative-going strobe at the occurrence of any one of the three, by which the external memory data buffer, if there is one, is enabled, and the external memory as well.) What this all amounts to is degrading the operating mode of his MCU to that of a P8032, which uses only external memory. If, then, he has the means to program an external EPROM or even just to write to an FRAM, which is all that's necessary and NOT rocket science, he could locate the bootloader there, serially load the code he wants to use in the FRAM, and then move it to the appropriate region in memory so that, next time he boots the MCU, the code he bootloaded will be located properly. FRAM's are available in large size, BTW. I've used 512 kB sized ones with wire-wrap adapters, to provide a big enough nonvolatile memory. By creative use of external logic, i.e. a few gates and jumpers, he could manipulate the high-order addresses to make the bootloader appear in the correct place for bootloading, yet move it out of the way to run his newly-loaded program. Clearly there are many options. No matter what he does, though, he'll not be able to erase or reprogram this particular part.


When you don't know how to do something, you always find it difficult. Once you know how, it's easy. That's especially true with digital hardware.

The cheapest way to handle this would be to beg RAMTRON for a sample of one of those FRAM's and an adapter for the TSOP-II to a more convenient footprint. Then, with a parallel port on his PC, he can build a device with which to write to it. Even easier, he could use an EPROM, the easiest of which is a 2716, of which there are still a few around. A programmer for one of those would consist of a few counters (3 4-bit counters, perhaps) and a one-shot to time the maximal 50 ms time requirement for it. Then the parallel port can, byte-by-byte, be used to program the EPROM from the parallel port, using one input bit to monitor the post-write timeout provided by the one-shot. The whole thing would cost less than $10, even at today's inflated prices.


You're right, it's not for the faint of heart, nor is it a task for a total newbie, as he indicates he is, but it's not a budget buster.


Well, that's probably true. If he's bent on using THIS PARTICULAR DEVICE, he's got a hard row to hoe. If, however, he has a the intelligence to manage the task in the first place, he'll quickly see that he needs, at least, to obtain a serially programmable MCU, costing less than $2 or so on eBay
http://www.ebay.com/itm/IC-AT...3cbbe50d2b
for example, and be done with it. It's not certain that he even requires an evaluation board, provided he has done the research to enable him to buile the programming circuit, usually consisting of little more than a MAX-3232A and a serial connector.


That's the situation that confronted those of us who wanted to use the 805x's back in the early '80's. There were tools, of course, but they were VERY costly and cumbersome, There were no IBM PC's yet ... at least not evolved enough to be of use, and the tools Intel provided cost more than a new Benz. We had to read the datasheets, write our own software, and build our own hardware. Fortunately, the datasheets included programmer schematics for the EPROM-based parts. We hadn't learned about microprocessors or microcontrollers in college because they didn't exist back in the '60's. We had to do exactly what this fellow, the original poster, has before him. I'm of the opinion that we must credit him with at least as much intelligence as I had back then. Perhaps not as much as you possess, as you always seem to know better, but a reasonable amount. As a result, I have to believe he's at least clever enough to do what I did back when it was totally necessary. Back then, there was no 8052.COM.



You're not the first to suggest that this is a fool's errand for one who's totally inexperienced. However, aside from my own belief that the O/P needs to consider his goal before deciding what to do, he should also consider that he can build the same circuit with a modern, serially reprogrammable, device, for which PC-based serial loaders are available from the chip manufacturer, that could be built with the old Intel part, he may actually prefer to suffer the consequences of starting from scratch. Until he tells us what he wants and why he wants it, we can only guess.

I believe he should be encouraged to do what he wants, and not be dissuaded because there's an easier way. People have walked up the half-dome in Yosemite national Park. Others have climbed the face. It's just a personal choice.

As for your car analogy, I routinely run across situations where someone has an old car worth less than $300, and wishes to spend two years and $30k on it to restore it to "original" condition. Sometimes that's because it is of the same vintage as they are, and in others it's because it was the first car they learned to drive. I've seen TV programs on which they spend $100k on a car worth $50 to restore it, even though the restored value is on the order of $10k. I've seen TV programs on which they take a new, $50k vehicle, modify it at an expense of $200k, to make it into a vehicle worth no more than $10k. I can't make any sense of it. Can you?

RE