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on the C64, if not using floats, disable basic ROM in startup to gain another 8Kb of RAM

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MEMTOP is adjusted to $d000. This gives us 50 Kb of contiguous program RAM space. ($0801-$CFFF)
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Irmen de Jong
2024-11-04 21:24:53 +01:00
parent e514eeba17
commit fddd390d31
13 changed files with 259 additions and 228 deletions
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docs/source/technical.rst
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@@ -75,6 +75,15 @@ The bank number is not translated into assembly (only as a comment)::
Calls with automatic bank switching like this are not safe to use from IRQ handlers. Don't use them there.
Instead change banks in a controlled manual way (or not at all).
.. note::
On the C64, the Basic ROM is *banked out* by default when running a Prog8 program, because
it is not needed. This means we get access to another 8Kb of RAM at that
memory area, which actually gives us a 50 Kb contiguous RAM block from $0801 to $d000 (exclusive).
This means you can create programs of up to **50 Kb** size with prog8 on the C64.
However, if your program uses floats, Prog8 *does* need the Basic ROM for the floating point routines,
and it won't be banked out. Such programs are limited to the regular size of about 38 Kb.
Be aware that the bank setting is only done if you are not using ``%option no_sysinit``!
.. _symbol-prefixing: