Welcome.

1. You might've missed the point of modern microcontrollers - they have FLASH program memory, i.e. they are many (thousands) times reprogrammable, purely electrically. The vast majority of them does not require any special programmer and can be reprogrammed directly in the circuit, via some sort of serial protocol (either SPI-like, or UART-like, or some other).

The 8052.com SBC is originally intended to be used with an AT89S8253 type microcontroller, which is reprogrammable through a SPI-like protocol, for which there is a circuit on the board adopting signals from the parallel (LPT) port of the PC. Now, as these are quite rare on nowadays' PCs, I would not recommend this one. When I play with the SBC, most of the time I use a P89V51RD2, which has more FLASH and RAM, and can be programmed through the UART (serial port). Now these are rare on modern PCs, too, but there are cheap and working USB-to-serial cables available around.

You still can use any '51-compatible mcu capable of running out of external memory (most of those which come in DIP40 package do), exactly as you've described, but there is little reason to do so these days.

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I will now assume you have given up the idea of running the '51 from external code memory :-)

As far as BASIC52 is concerned, you have basically two options: either to burn the original BASIC51 into the MCU, plug in an external RAM into the respective socket on the SBC, make some knife-and-wire modifications on the board (as the RAM is there mapped to 8000h whereas BASIC52 expects it to be present at 0000h); or you go for the single-chip modification I concocted some time ago, which uses the internal memories to store the BASIC program and data. The published version is for AT89C51RD2/ED2 (which is unfortunately not available in DIL40 anymore), but I have a version for P89V51RD2, too.

2. Yes.

3. Probably yes, except that you might perhaps need to modify the software. SPI EEPROMs are quite rare, I don't quite understand Craig's motivation to use that. However, there are modern SPI serial FLASH chips, although not pin compatible, which might be worth trying to play with.

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All this said, Per might be right and you might be better off making the first experiments with some ready-build and simpler=cheaper board (although I admit I don't know the market of these). The concept of external memories is mostly dead nowadays at least in the world of 8-bit microcontrollers. It's getting increasingly harder to find a SRAM in DIP package. As I explained above, the circuitry for programming from parallel port is probably useless, too. An USB interface for programming might serve a better purpose.

However, should you decide to build the 8052.com SBC anyway, <advertisement>I do have SBC PCBs for sale, and a couple of P89V51RD2BN too, and I sit wihin the EU.</advertisement> (I hope the webmaster won't be too angry at me for this minor ad :-) )

Jan Waclawek