Master MOS: reset clears 1 byte of persistent FS zero page
When clearing zero page on reset, all versions of the Master MOS start clearing from $cf: https://github.com/tom-seddon/acorn_mos ... t.s65#L288
This feels like a bug, in that either the OS should be responsible for clearing all of this region, or none of it. But I imagine every FS clears the value itself, if it cares about it, so it's not a big problem. I thought it interesting to note though.
(The corresponding code in OS 1.20 starts at $e2: https://github.com/bitshifters/bbc-docu ... .txt#L5246 - which makes a bit more sense, as $e2 is the start of non-VDU workspace. (See https://tobylobster.github.io/mos/mos/S-s2.html#SP11.) Presumably the VDU driver was considered responsible for taking care of itself.)
--Tom
When clearing zero page on reset, all versions of the Master MOS start clearing from $cf: https://github.com/tom-seddon/acorn_mos ... t.s65#L288
This feels like a bug, in that either the OS should be responsible for clearing all of this region, or none of it. But I imagine every FS clears the value itself, if it cares about it, so it's not a big problem. I thought it interesting to note though.
(The corresponding code in OS 1.20 starts at $e2: https://github.com/bitshifters/bbc-docu ... .txt#L5246 - which makes a bit more sense, as $e2 is the start of non-VDU workspace. (See https://tobylobster.github.io/mos/mos/S-s2.html#SP11.) Presumably the VDU driver was considered responsible for taking care of itself.)
--Tom
Statistics: Posted by tom_seddon — Sun Jan 26, 2025 1:56 am