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--- nexys_board_switches [2016/11/20 22:20]
– created gurce
+++ nexys_board_switches [2018/02/17 23:33] (current)
– Switch 12 no longer used for hypervisor debug output (shift-key on usb keyboard is) gurce
@@ Line 3: / Line 3: @@
 I thought I'd better document the functionality of various switches on the Nexys board, for easy reference:
-===== Switch 12 =====
+===== Switch 0 - Turn off interrupts =====
+This switch is handy when in trace mode and you're constantly getting the pc moving away from your current code due to interrupts.
+===== Switch 8 - Dummy 8KB cartridge =====
+This was mentioned in one of Paul's blog posts:
+https://c65gs.blogspot.com.au/2018/01/fixing-various-niggly-problems.html
+> Fourth, the Nexys4DDR boards thought that they always had an 8KB cartridge plugged in if switch 8 was not set.  This was a debug thing I put in when getting the cartridge interface to work some time ago, and of course then promptly forgot about, resulting in a few hours of lost time trying to figure out why on earth I was seeing 30719 BYTES FREE, but no actual data in the mapped cartridge.
+===== Switch 11 - Trace mode on =====
+Turn Switch 11 on at any time to turn trace-mode on (i.e., freeze the PC, so that you can step-into/over instructions manually). You can turn this on at boot-up time, if you want to step from the initial startup of the machine.
+===== Switch 12 - Hypervisor debug output =====
+__NOTE__: (18/02/2018) Switch 12 is no longer used for the hypervisor debug output. It is now triggered via the Shift key on the USB keyboard attached to the hardware.
 This switch decides whether Hypervisor debug output will be shown (via the remote serial monitor output) or not.
@@ Line 28: / Line 47: @@
 Paul.
+===== Switch 15 - Pause after kickstart messages =====
+If Switch 15 is turned on prior to booting up the system, the system will pause after displaying all the kickstart messages (giving you time to read and review them). Simply turn off the switch to proceed with the boot-up process.
+===== Miscellaneous =====
+==== Selecting between multiple ROMs on reboot ====
+While not a nexys switch but a press of keys on the keyboard, this tip from Paul was worth noting:
+> Alternatively we could make patches for the C65 ROM to achieve this, and pick between which ROM we boot with (already implemented by holding down 0 through 9 on reset).