Ohhh, why has this gone unanswerd for so long when there are so many good \mu Cs available?
I don't know what knid of bus control fundamentials you are trying to learn (are you simply trying to learn how to R/W a bidirectional bus or trying to figure out how to connenct memory chips to a processor that uses a common bus for the address and data lines like the older MC68HC11's and 8051's) so I'll throw out a list of the microprocessors I use on a regular basis.
Though I'm probably a day late and a dollar short here's my list of choices:
Atmel AVR microcontrollers(
http://www.atmel.com/products/avr/ ): I prefer these to PICs. No real reason I've just had the opportunity to play with 90 series and tiny/mega series chips more.
Microchip PICs( http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=74 ): Very useful little devices though limited in their ability to do more complex functions (18 series has a beefier ALU so can handle more cplx functions).
The above two are basically 8-bit controllers and can be found in various packages and configurations. You can do a lot of things with the above two chips. If you just want to learn how to move data into and out of the processer or rather on or off a bus then I'd recommend either series of chip. They are CHEAP and VERY powerful.
8051's: These can be purchased from a few manufacturers such as Atmel or Maxim. If you want to learn how to bemux an address bus into an address/data bus then get(or just read the documentation) for one of these. It's harder to find muxed A/D busses these days but the chips are still available. Personally, IMO this is a good skill to have but not necessary because most microcontrollers sold today can be had with separate pins for the address and data buses.
Motorola MC68HC11's(8's,12's or 16's): these are great chips though they are EOL. My first microcontroller project was built around an old A series HC11. You can still buy them for around 5 bucks and are available with internal demux (HC11F1) or common AD bus (HC11E series if I recall). The HC11F1 series is very powerful and you can learn a lot about more advanced microcontroller design by playing with thess chips.
The above two are very powerful processors (8051 variant-8061 was used for years by Ford motor company to control engines in the EEC IV ECU, and the 68 series of processors were used by GM for the same purpose IIRC) and one is well served to spend the $25 USD needed to build a basic experimenters board based on either series of processor.
386/486(various manufacturers): These are now available in a plethora of packages with many built-in functions. If you have a gnu-c compiler then you can easily code for the above. Inexpensive (compared to full-blown Intel/AMD desktop processors) but still a little more costly than any of the processors mentioned thus far. I wouldn't start at this level though it is possible.
Renesas H8--formerly Hitachi/Mitsubishi( http://america.renesas.com/fmwk.jsp?cnt=mpumcu_category_landing.jsp&fp=/products/mpumcu/&site=i ): Another great series of controller. You could group the H8 series with the HC11 and the 8051 series because they are similar in design and usage. I havn't done a lot with this chip series--one design used an H8 to control the temps of 32 enclosures and forwared the temperature readings to a remote PC(the company I worked for was using H8's for a production design--for what I don't know--so I pulled a few off of a reel before they when used...Shhh don't tell anyone).
Anyway, I could go on for hours probably because there are sooooo many microcontrollers available today. TI makes them, many manufacturers have ARM based processors, Motorolla has a few different microC architectures and on and on. If you want to learn the basics of movin data Get and AVR(or PIC). If you want to learn to use a more powerful processor then go with a cheap HC11 or 8051 (H8's are a little more $$$ IIRC).
Hopefully this helped a little.
Good luck.
