Port 8bitworkshop monobitmap.c sample: UxROM mapper with CHR RAM

[Copilot]

Adds the monobitmap sample demonstrating UxROM mapper (mapper 2) with CHR RAM — no transpiler changes needed, the infrastructure already supports arbitrary mapper numbers and NESChrBanks=0.

Sample

Simplified port of 8bitworkshop's monobitmap.c. Uploads custom tile patterns to CHR RAM at runtime via vram_write(), arranges them in the nametable to draw a bordered rectangle with diagonal fill, and uses poke() for direct PPU register manipulation.

<!-- monobitmap.csproj -->
<NESMapper>2</NESMapper>
<NESChrBanks>0</NESChrBanks>

The original's inline assembly delay loops, vram_read() with pointers, and abs() are not portable to dotnes — this port focuses on the core UxROM + CHR RAM + poke() demonstration.

Changes

• samples/monobitmap/ — Program.cs, .csproj (mapper 2, chrBanks=0), chr_generic.s placeholder
• src/dotnes.tests/ — Debug/release test DLLs, InlineData entries in TranspilerTests.Write, verified ROM snapshot
• docs/8bitworkshop-samples.md — monobitmap moved from 🔴 Complex → ✅ Implemented

ROM verification

iNES header: 4E45531A 0200 2000 — mapper 2 (UxROM), 0 CHR banks (CHR RAM), 2 PRG banks. 32,784 bytes total (16 header + 32K PRG, no CHR ROM). All 389 tests pass.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Port 8bitworkshop sample: monobitmap.c</issue_title>
<issue_description>Port the monobitmap.c sample from 8bitworkshop. This demonstrates UxROM mapper with CHR RAM for a 256x240 monochrome bitmap.

Features needed

• UxROM mapper support
• CHR RAM (vs current CHR ROM from .s files)
• Direct PPU register manipulation via poke() (Implement poke(ushort, byte) for direct memory-mapped I/O #94)

Complexity: High

Requires mapper + CHR RAM infrastructure.

8bitworkshop reference

https://8bitworkshop.com/ (monobitmap.c)
</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Port 8bitworkshop sample: monobitmap.c #101

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[Copilot]

Pull request overview

Adds a new monobitmap sample to the dotnes repository to demonstrate UxROM (mapper 2) with CHR RAM (NESChrBanks=0), including ROM snapshot coverage and documentation updates for the 8bitworkshop port status.

Changes:

• Add samples/monobitmap/ (Program + project settings for mapper 2 / CHR RAM).
• Add transpiler snapshot coverage for monobitmap (InlineData + verified ROM + test DLLs).
• Update 8bitworkshop sample status documentation to mark monobitmap.c as implemented (simplified).

Reviewed changes

Copilot reviewed 5 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/dotnes.tests/TranspilerTests.cs	Adds snapshot test cases for the new monobitmap sample with mapper=2 and chrBanks=0.
src/dotnes.tests/TranspilerTests.Write.monobitmap.verified.bin	Adds the verified ROM output snapshot for monobitmap.
src/dotnes.tests/Data/monobitmap.release.dll	Adds prebuilt release test input DLL for the snapshot tests.
src/dotnes.tests/Data/monobitmap.debug.dll	Adds prebuilt debug test input DLL for the snapshot tests.
samples/monobitmap/monobitmap.csproj	New sample project configured for UxROM + CHR RAM.
samples/monobitmap/chr_generic.s	Placeholder CHR segment file consistent with CHR RAM builds.
samples/monobitmap/Program.cs	New sample program that uploads tiles to CHR RAM and draws a simple monochrome scene using VRAM ops and poke().
docs/8bitworkshop-samples.md	Marks monobitmap.c as implemented (simplified) and updates summary counts.