* Most parallel ROMs of at least 4KiB should be usable, just short the excess uppermost address pins to GND and ensure pin compatibility, e.g. through an adapter PCB.
* In case there are too many memory errors and they are already overwritten on screen before you can analyze them, you can trigger a hardware NMI, which will stop the memtest routine. Though afterwards you'll have to start over by triggering a reset.
After starting up, most of the screen will be empty.
* In the top left you can see a `#` character. This is the cursor. If more defects are found than fit on the screen, the output will start over at the top, overwriting previous entries. The cursor indicates the position after the last printed output.
* Each faulty memory access looks like this: `DEAD>BEEF`.
* The part left of the `>` sign is the memory address at which the fault occured.
* The part right of the `>` sign is two bytes: First the byte that was written to this address, then the byte that was returned when reading from the same address.
* If the written byte reads `XX` instead of a hex byte, the byte that was actually written is the XOR of the high and low bytes of the address, i.e. `(DE xor AD)`. If you only see `XX` faults, there may be a fault in the address lines, rather than individual memory cells or output lines.
* In the bottom right you can see 3 quickly alternating characters. The first two chars are the textual (PETSCII characters, not hexdumped) representation of the memory address currently being tested. The third char is the character written to said memory address in the current pass.
* When all memtest passes have completed, there will be an additional `=` character left of these chars.
* When the memtest routine was interrupted by an NMI, there will be a `!` instead.
* When the screen is not cleared (filled with random characters), and the first line starts with `ZF***ZF` (`*` being other seemingly random characters), a fault in the first few bytes of the zero page were detected. Since the memtest uses this area to store its state, the test is terminated prematurely.
