# Prompt64 0.2 memory map

| Range | Use |
| --- | --- |
| `$0801-$85FF` | PRG header, text, constants, initialized data, BSS budget |
| `$8600-$87FF` | enforced low-memory growth reserve |
| `$8800-$89FF` | top border sprite buffer |
| `$8A00-$8BFF` | bottom sprite buffer A |
| `$8C00-$8DFF` | bottom sprite buffer B |
| `$8E00-$8FFF` | guard/free area |
| `$9000-$A3FF` | NOLOAD 64×40 transcript characters and colors |
| `$A400-$A7FF` | 40×25 VIC-II screen |
| `$A800-$BFFF` | NOLOAD dashboard row store and remaining high RAM |
| `$C000-$CFFF` | NOLOAD compiler scratch; software stack grows below `$D000` |
| `$D000-$DFFF` | I/O window |

The project-owned `client/link.ld` shadows Rust-MOS's C64 script but retains
its `unmap-basic.o` startup and `$D000` stack policy. Prompt64 does not add
duplicate `$01` banking.

The screen moved from `$8400` to `$A400` so low code and BSS can grow toward
the fixed sprite buffers without reducing the transcript. VIC-II memory
control selects the `$A400` screen and the character ROM visible at `$9000`;
the screen's sprite-pointer table is at `$A7F8`.

The transcript and dashboard are explicitly initialized at runtime because
their sections are NOLOAD. The build emits `build/PROMPT64.map`, limits the PRG
to 32,257 bytes, asserts that low sections end before `$8600`, and checks every
fixed NOLOAD region. The physical sprite boundary is `$8800`, so both the PRG
size gate and linker assertion preserve a 512-byte reserve.