W65C816SXB - WDC Xxcelr8r Engineering Development System-Board Featuring The W65C816S 8/16-bit Microprocessor, W65C21 PIA, W65C22 VIA and W65C51N ACIA

The W65C816SXB has a 65C02 compatible processor which can be switched into 16-bit mode. The board is fully featured with 4 parallel ports, 4 timer/counters and 1 serial port. One of the parallel ports on the system VIA is connected to a USB fifo which allows fast connection to a PC for uploading files. The board has 32KB of SRAM and 128KB of flash. The flash is visible as a 32KB sized page in the top half of the processor memory. The system VIA can also be used to select the page of flash that is currently visible. Two small pads could be wired to ground to select the flash page which is visible. A large XBUS expansion bus contains signals which can be used for adding more expansion e.g SRAM, FLASH, Video.The included flash contains a simple interface program which is designed for communicating with WDC's software. This software only runs on Windows. An alternative python scriptfor uploading (sxb.py) can be found at forum.6502.org, search for "W65C816SXB and the Single Linux".This board was previously priced at 200 US dollars. It is a much better bargain at the new price.

The W65C51N ACIA chip is buggy and you will be stuck doing a software workaround.The IDE is broken so don't ever bother trying to use it. Worse it does not appear that they will ever fix it.You will have to learn to use your own editor and build using batch and/or make files.Moving on, the debugger is fickle and the simulator mostly works. The worse bugs being that it hangs when you hit run and that it displays 8 bit registers when you are running 16 bit simulation!They should release a new board with a fully working W65C51N ACIA chip and at this point they should release the source code to the development environment and allow the community to fix the bugs and make improvements.

I purchased two of these. I'm not new to writing assembly and wanted to learn the 65816 instruction set. The tools are old, but they work. I was able to compile and upload. But I noticed a problem. The board would crash any time I tried to access anything in a data bank other than zero. Long story short: It looks like U15 (CM078B/CD4078B) is too slow for this board to run at 8Mhz when switching into or out of data bank zero. To help prove this, I removed the clock chip and put in my own. As long as I stayed in DB0, I was able to overclock to 10Mhz. BUT: Accessing any Data Bank other than zero required an under-clock to 5Mhz. Other than this, it's a good board.