Add MEGA65 (native C65) and Commander X16 targets - #1
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- target=65: native MEGA65/C65 mode - screen $0800, BASIC $2001, C128-derived
KERNAL, self-contained print helpers, ROM-independent SYS-stub launcher.
New files mega65.def / mega65.asm.
- target=216: Commander X16 - VERA video (all drawing via CHROUT/PLOT, no direct
screen RAM, fast-scroll off), ISO charset so mixed-case SD/HostFS filenames
render as letters, SYS-stub launcher. New files x16.def / x16.asm.
- Both added to the shared CBM-FileBrowser.asm behind "!if target" guards, with
Makefile rules and prebuilt binaries in programs/ (fb65, fbx16).
- Fix a latent parseext infinite loop: its outer loop steps X by the 4-byte
slot size and stopped only on X == extensions_max, but the table is not a
whole multiple of 4 ("tcrt" is 5 bytes), so X could step past it. Terminate
on X >= extensions_max (bcs) instead of == (beq). Only bites when a filename
has a non-matching extension (e.g. the X16's HostFS "NAME.PRG"); safe for all
targets.
- Docs: MEGA65.md, X16.md.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The SYS-stub launcher runs machine-language programs (the bulk of the software) but cannot RUN a pure BASIC program: no SYS token means it resets, and a stray $9E byte can make the parse jump to a bad address. Document this shared limitation in X16.md and MEGA65.md; a proper LOAD-then-RUN hand-off into BASIC is future work. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Adds two new build targets to CBM-FileBrowser, plus one shared bug fix. Both new ports boot, browse directories, scroll, and launch programs, verified in their emulators (Xemu / x16emu). Existing targets are untouched and still build clean.
MEGA65 — native C65 mode (
target = 65)Runs in the MEGA65's native mode (not GO64): loads at
$2001with a BASIC-10SYSstub, screen$0800, colour RAM$D800. The C65 KERNAL is C128-derived, so the portable$FFxxjump table is reused; the C128 VDC/MMU code is replaced with C65-appropriate init, andPRNSTR/PRNINT/CLEARSCREENare provided locally (no C64 BASIC ROM). Two MEGA65-specific details were needed: zero the KERNAL's 32-bitLOADdestination bank bytes ($AF/$B0) so directory/program loads land in bank 0, and use an 80-column screen stride. Launch parses theSYSaddress out of the loaded program's$2001stub and jumps to it (ROM-independent).New:
sources/mega65.def,sources/mega65.asm,programs/fb65,MEGA65.md.Commander X16 (
target = 216)The X16 has a C64-derived KERNAL (standard
$FFxx, BASIC$0801, 65C02) but VERA video — the text screen is not in CPU address space. So all drawing goes through the KERNAL screen editor (CHROUT/PLOT), fast-scroll is off, andclearlistis reimplemented withPLOT+CHROUT. The browser sets 40x30 text mode and ISO mode (so mixed-case SD-card/HostFS filenames render as letters). Launch uses the same ROM-independentSYS-stub parser (from$0805).New:
sources/x16.def,sources/x16.asm,programs/fbx16,X16.md.Shared fix:
parseextinfinite loopparseext's outer loop steps X by the 4-byte slot size and terminated only onX == extensions_max, but the extensions table isn't a whole multiple of 4 ("tcrt"is 5 bytes), so X could step pastextensions_maxand loop forever. It only triggers when a selected filename has an extension that matches nothing — which never happens with CBM disk names (no extension) but does on the X16's HostFS names likeNAME.PRG. Fixed by terminating onX >= extensions_max(bcsinstead ofbeq) — a safe hardening for every target.Build
cd sources && makebuilds all targets includingfb65.prgandfbx16.prg. Both new targets sit behind!if target = 65/!if target = 216guards.🤖 Generated with Claude Code