Got this board about a week ago, but I have no clue what flash chip to buy or how to program it.

The software tools didn't recognize the board, and I couldn't figure out how to load a binary anyway. So I wrote a hexfile processor which loads programs through the built-in monitor, which works very well.

But I guess the flash rom needs to be programmed separately before being inserted into the socket? If so that seems like a pain to me. If not, then how is it done? I couldn't find anything about it in the documentation.

This is a pretty nice board though. I'm impressed with the large number of I/O ports and the large connector could be used to interface into existing circuits. With a program loaded into flash rom, the 32k sram should be more than enough for most 16-bit microcontroller purposes.

It was $99, but worth it to have some "real hardware" to test stuff on. If anyone knows how to get the flash rom working I'd love to know, thank you.

The flash ROM WDC have used is software programmable. According to the data sheet they are using two pins to control the top address bits A<17:16>.

On the 816SXB there are external pull ups resistors to make A<17:16> = %11 on start up you board is probably the same. Change the pins to low outputs to select the other banks. In my code I make the pin an input to return it to high.

The unlock sequence is documented in the flash ROM's data sheet. It consists of a sequence of writes of specific values at specific offsets from the base address of the ROM.

Make sure you get a copy of ROM before trying to write to it - just in case. The debugger has a memory export feature. I'd recommend test writing to a area where WDC don't have any code in their bank to start just in case it screws up.

Alternatively buy a spare flash ROM and a PLCC32 adaptor for use with an EEPROM programmer or build a circuit with another microcontroller to download code into it (e.g. PIC or AVR with USB Serial and a socket to hold the ROM). There were a couple of projects on here a year or so ago to build such circuits for DIP flash ROMS.

I have been working on a tool to download into my 816SXB but its not working yet - There's a bug in the XMODEM routine and I haven't had time to work on it. The code is here:

https://github.com/andrew-jacobs/w65c816sxb-hacker

_________________
Andrew Jacobs
6502 & PIC Stuff - http://www.obelisk.me.uk/
Cross-Platform 6502/65C02/65816 Macro Assembler - http://www.obelisk.me.uk/dev65/
Open Source Projects - https://github.com/andrew-jacobs

Thanks for all the info. There was no flash rom chip installed in the board, which is confusing because the datasheet has this in the feature list:

1 x 128Kbytes FLASH ROM (32PLCC Socket) mapped as upper 32KB of Memory Map with overlays off of 2 IO pins from the W65C265S (P43 = FA15; P44 = FAMS).

I can't find such a chip anywhere, they are all larger now. Will any 5V part work in this, even if the board can't access the entire thing?

The socket takes a SST39SF010A (the same as the other SXBs). The W65C816SXB uses a 70nS version but you can get faster ones. The W65C265SXB is half the speed so a 70nS will work. I had a 55nS sample to hand that works nicely.

It should be writeable using software (I haven't tried this yet) but don't place the string 'WDC' at $00:8000 until you are completely sure the ROM works otherwise the monitor will transfer control to it at startup and your system could lock up until the ROM is removed.

_________________
Andrew Jacobs
6502 & PIC Stuff - http://www.obelisk.me.uk/
Cross-Platform 6502/65C02/65816 Macro Assembler - http://www.obelisk.me.uk/dev65/
Open Source Projects - https://github.com/andrew-jacobs

Thank you VERY much.