Run editor/BREAK/run editor should result in no data loss (provided startup mode doesn't interfere with the region).
The level data has an identifier, so it can be detected.
Does the data need moving down 256 bytes when used by the editor? To ensure that the BASIC stack doesn't interfere? I think USR in GLOADER might use the BASIC stack. Might just be a question of setting HIMEM often enough though.
Run editor/BREAK/run editor should result in no data loss (provided startup mode doesn't interfere with the region).
The level data has an identifier, so it can be detected.
Does the data need moving down 256 bytes when used by the editor? To ensure that the BASIC stack doesn't interfere? I think
USR
inGLOADER
might use the BASIC stack. Might just be a question of setting HIMEM often enough though.