Target
From MSX Game Library
Target type description.
Contents
Basic program
| Target | Description |
|---|---|
| BIN | BASIC binary program (starting at 8000h) |
| BIN_USR | BASIC USR binary driver (starting at C000h) |
| BAS | Alias for BIN |
MSX-DOS program
| Target | Description |
|---|---|
| DOS1 | MSX-DOS 1 program (starting at 0100h) |
| DOS2 | MSX-DOS 2 program (starting at 0100h) |
| DOS | Alias for DOS1 |
Plain ROM program
| Target | Description |
|---|---|
| ROM_8K | 8KB ROM in page 1 (4000h ~ 5FFFh) |
| ROM_8K_P2 | 8KB ROM in page 2 (8000h ~ 9FFFh) |
| ROM_16K | 16KB ROM in page 1 (4000h ~ 7FFFh) |
| ROM_16K_P2 | 16KB ROM in page 2 (8000h ~ BFFFh) |
| ROM_32K | 32KB ROM in page 1&2 (4000h ~ BFFFh) |
| ROM_48K | 48KB ROM in page 0-2 (0000h ~ BFFFh) |
| ROM_48K_ISR | 48KB ROM in page 0-2 (0000h ~ BFFFh) with ISR replacement |
| ROM_64K | 64KB ROM in page 0-3 (0000h ~ FFFFh) |
| ROM_64K_ISR | 64KB ROM in page 0-3 (0000h ~ FFFFh) with ISR replacement |
| ROM | Alias for ROM_32K |
Mapped ROM program
Note: "MegaROM" refers to a ROM of 128KB or more. Even though they are not widely supported, there is nothing to prevent you from creating a 64KB ROM using a mapper. We therefore prefer to use the term Mapped ROM here rather than MegaROM.
Setup
You can create program using one of the ROM mappers supported by MSXgl:
| Target | Description |
|---|---|
| ROM_ASCII8 | ASCII-8: 8KB segments for a total of 64KB to 2MB |
| ROM_ASCII16 | ASCII-16: 16KB segments for a total of 64KB to 4MB |
| ROM_KONAMI | Konami MegaROM (aka Konami4) 8KB segments for a total of 64KB to 2MB |
| ROM_KONAMI_SCC | Konami MegaROM SCC (aka Konami5): 8KB segments for a total of 64KB to 2MB |
In your build.bat, chose as target one of the above target type. You can specify the ROM size (in KB) in the ROMSize variable. Default value is 128 (KB). Any multiple value of the mapper's segment size is valid, but I recommend using powers of 2 values (64, 128, 256, etc.) to help emulators to autodetect the right mapper.
Some Build Tool configuration examples:
//-- 128KB ASCII-8 mapped-ROM target = ROM_ASCII8; //-- 4MB ASCII-16 mapped-ROM target = ROM_ASCII16; ROMSize = 4096; //-- 512KB Konami SCC mapped-ROM target = ROM_KONAMI_SCC; ROMSize = 512;
See projects/samples/s_vgm sample for a concrete use case.
Build
Mapped-ROM use a system of sub-page (called "bank" here) the user can redirect to any segment of the ROM. Those banks are mapped to page #1 and #2 (4000h~BFFFh) of the memory space. The number of banks depends on the size of the mapper:
- 8KB mappers have 4 banks:
- bank 0: 4000h~5FFFh
- bank 1: 6000h~7FFFh
- bank 2: 8000h~9FFFh
- bank 3: A000h~BFFFh
- 16KB mappers have 2 banks:
- bank 0: 4000h~7FFFh
- bank 1: 8000h~BFFFh
The Build Tool build the first 32KB of the mapped-ROM like a 32KB plain ROM. This represents the first 4 segments for a 8KB mapper and the first 2 for a 16KB mapper.
The following segments are added to the ROM by the Build Tool by searching for files with a particular nomenclature: <project_name>_s<segment_number>_b<target_bank>.c.
For example with a ASCII-8 ROM of 128KB:
program.c | Main program including segment #0~#3 (4*8KB)
program_s4_b2.c | Segment #4 to be used in bank #2 (8000h~9FFFh)
program_s5_b3.c | Segment #5 to be used in bank #3 (A000h~BFFFh)
| No files found for segment #6 to #14: padding data added to the ROM
program_s15_b2.c | Segment #15, the last one, to be used in bank #2 (8000h~9FFFh)
Segment selection
In your program, you can then select what segment is visible from what bank using the SET_BANK_SEGMENT(bank, seg) macro. For example, to put segment 15 of the above example in bank 2, just use SET_BANK_SEGMENT(2, 15);
For information, at startup, the following segments are selected:
- 8KB mappers:
- bank 0: segment 0
- bank 1: segment 1
- bank 2: segment 2
- bank 3: segment 3
- 16KB mappers:
- bank 0: segment 0
- bank 1: segment 1
Targets overview
| Target | Selected at boot | Description | |||
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | ||
| ROM_8K | BIOS | Cart | RAM | RAM | 8KB ROM in page 1 (4000h ~ 5FFFh) |
| ROM_8K_P2 | BIOS | RAM | Cart | RAM | 8KB ROM in page 2 (8000h ~ 9FFFh) |
| ROM_16K | BIOS | Cart | RAM | RAM | 16KB ROM in page 1 (4000h ~ 7FFFh) |
| ROM_16K_P2 | BIOS | RAM | Cart | RAM | 16KB ROM in page 2 (8000h ~ BFFFh) |
| ROM_32K | BIOS | Cart | Cart | RAM | 32KB ROM in page 1&2 (4000h ~ BFFFh) |
| ROM_48K | BIOS | Cart | Cart | RAM | 48KB ROM in page 0-2 (0000h ~ BFFFh) |
| ROM_48K_ISR | Cart | Cart | Cart | RAM | 48KB ROM in page 0-2 (0000h ~ BFFFh) with ISR replacement |
| ROM_64K | BIOS | Cart | Cart | RAM | 64KB ROM in page 0-3 (0000h ~ FFFFh) |
| ROM_64K_ISR | Cart | Cart | Cart | RAM | 64KB ROM in page 0-3 (0000h ~ FFFFh) with ISR replacement |
| ROM_ASCII8 | BIOS | Cart | Cart | RAM | ASCII-8: 8KB segments for a total of 64KB to 2MB |
| ROM_ASCII16 | BIOS | Cart | Cart | RAM | ASCII-16: 16KB segments for a total of 64KB to 4MB |
| ROM_KONAMI | BIOS | Cart | Cart | RAM | Konami MegaROM (aka Konami4) 8KB segments for a total of 64KB to 2MB |
| ROM_KONAMI_SCC | BIOS | Cart | Cart | RAM | Konami MegaROM SCC (aka Konami5): 8KB segments for a total of 64KB to 2MB |
| DOS1 | RAM | RAM | RAM | RAM | MSX-DOS 1 program (starting at 0100h) |
| DOS2 | RAM | RAM | RAM | RAM | MSX-DOS 2 program (starting at 0100h) |
| DOS2_ARG | RAM | RAM | RAM | RAM | MSX-DOS 2 program with command line arguments (starting at 0100h) WIP |
| BIN | BIOS | BASIC | RAM | RAM | BASIC binary program (starting at 8000h) |
| BIN_USR | BIOS | BASIC | RAM | RAM | BASIC USR binary driver (starting at C000h) |