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Realtime · 12th Feb 2023, 11:16 pm

The variables need to stay at FF8 because they are accessed using negative addressing relative to P2, which conveniently is zero after a reset. As relative addressing can only point +/- 128 bytes it’s not possible to point all the way down to the F00 area. If P2 had to be initialised to point to F00 then the fast loader code would exceed the available space.

12th Feb 2023, 11:16 pm	#184
Realtime Hexode Join Date: Jan 2021 Location: Ashford, Kent, UK Posts: 318	Re: Yet another MK14 tape interface (ESP32). The variables need to stay at FF8 because they are accessed using negative addressing relative to P2, which conveniently is zero after a reset. As relative addressing can only point +/- 128 bytes it’s not possible to point all the way down to the F00 area. If P2 had to be initialised to point to F00 then the fast loader code would exceed the available space.