DiagROM (Amiga CD32)
A great way to diagnose issues with the Amiga CD32 is to replace the main Kickstart ROM with a DiagROM.
You can program the DiagROM on to a M27C800.
When you boot up you should see the flashing screen then tests running to let you know whats wrong if anything fails on boot.
After that you are presented with a screen where you would typically enter values on a keyboard (like the Amiga 1200) to perform further tests. As you cannot do this on the CD32, we can use a TTL to USB device (any that supports 5V TTL UART) such as this.
Make sure to set the voltage level to 5V if there is an option on the UART device, and then solder ground to any ground point, the RX going into the UART device (so the UART device to PC that is receiving data) to D644, and the TX (the UART from PC sending data to the Amiga) to D643.
Now download a serial monitor tool such as Putty or Serial Debug Assist (I use this). Set the COM port to that of your UART device, the speed to 9600, the mode to 8 bits, no parity and 1 stop bit and enable Terminal Mode.
If using Putty use these settings:
If using DiagROM v2 (released March 2025 onwards) then the serial port speed is 19600, but the developer has mentioned they may change it back down to 9600 so check the official page for that.
With this when you turn on the system it should instantly start outputting serial data to the terminal.
Listen out for the text when it asks you to press any key to enable serial. At this time send anything to the terminal (by typing say hi and pressing the Send button on the bottom right, not the enter key).
Once you do this the serial will output a menu system.
If using DiagROM v1.x In Serial Debug Assist this is messed up a bit as it doesn't wipe the text from underneath but you can still make it out. This is fixed in DiagROM v2.x.
However, it is basically showing you this menu.
So you can use Putty for a cleaner display, but I like the added support in Serial Debug Assist like telling you what COM ports have what names and quicker to setup than Putty. Simply make sure to use DiagROM v2 and there is no issue.
Now you can use the number keys next to each menu item, or the up and down then enter keys to navigate the menus and run tests.
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