"w65c265sxb hacker" is the tool that Bitwise created to make things simpler when tinkering with this development board from WDC, that have that model number.

While working with the clone I'm building, I realized that the rom selection instruction in the "hacker" is inverted (as I see it) against changing the register directly in the Mensch monitor.

The register is $DF024, and when cold booted, it has a value of $C0. That means to me: EEPROM BANK 0. Why #0? Because it's logic for me that after a reset the chip would set the first of the four available banks as the active one.

Changed to $C8, means to me: EEPROM BANK 1
Changed to $D0, is for me: EEPROM BANK 2
and changed to $D8, means EEPROM BANK 3.

But in the "hacker", it seems to me that it's:

$C0 = BANK 3
$C8 = BANK 2
$D0 = BANK 1
$D8 = BANK 0

I checked with the R instruction of the "hacker" and then read the $DF24 value, and got that information. I also put two LEDs attached to P43_FA15 and P44_FAMS and watched them light on and off when changing those values.

And finally, as I was able, thanks to Bitwise and it's utils, to burn its port of EhBasic in the EEPROM of the SXB clone.

And I realized that if I set R 0 with the hacker and then burn the EEPROM as he teaches, when I reset the board and read the $8000 memory, the EhBASIC code is not there.

But by changing $DF24 to $D8 with the M instruction of the Mensch monitor, then the bank selection makes the code to be shown and can be executed.

Is all of this me that is getting all of this the wrong way?

Thanks.

The flash memory is a 128K chip divided into 4 32K banks. The pins used to select the active bank of the flash memory (P43 & P44) are configured as input pins when the W65C265 is reset and two 3K pull-up resistors (R12 & R13) on the SXB board force the P43_FA15 and P44_AMS address lines high, so by default bank 3 is selected.

This bit of code changes the pin direction (PDD4 @ $DF24) and state (PD4 @DF20) to make the pins P43 and P44 low outputs when a 0 is need or an input when a 1 is needed on the address lines.

_________________
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