Create a mapped ROM - Revision history

Aoineko: /* Change segment visbile through bank */

2026-05-23T08:07:22Z

‎Change segment visbile through bank

Aoineko at 08:06, 23 May 2026

2026-05-23T08:06:16Z

Aoineko at 07:58, 23 May 2026

2026-05-23T07:58:16Z

Aoineko: /* NEO mapper */

2026-01-05T18:21:07Z

‎NEO mapper

Aoineko: /* Symbols */

2025-03-07T21:29:41Z

‎Symbols

Aoineko: /* NEO mapper */

2025-01-23T14:53:41Z

‎NEO mapper

Aoineko: /* Principles */

2025-01-04T23:41:03Z

‎Principles

Aoineko: /* Yamanooto & ASCII16-X */

2025-01-04T23:38:41Z

‎Yamanooto & ASCII16-X

Aoineko: /* NEO mapper */

2025-01-04T23:36:52Z

‎NEO mapper

Aoineko: /* Raw binary data */

2025-01-04T23:30:52Z

‎Raw binary data

@@ Line 31: / Line 31: @@
 Using MSXgl, you don't need to know the addresses or write because you only need to use the <tt>SET_BANK_SEGMENT(bank, seg)</tt> macro which takes care of associating a segment to a bank.
-For example:
+Example:
 <syntaxhighlight lang="c">
 SET_BANK_SEGMENT(1, 8); // Set segment #8 visible through bank #1.

@@ Line 1: / Line 1: @@
-To create cartridges larger than 64 KB, {{MSXGL}} allows to use several types of mapped-ROM (often called MegaROM).
+To create cartridges larger than 64 KB, {{MSXGL}} allows to use several types of mapped ROM (often called MegaROM).
 This documentation primarily explains how standard mappers work: ASCII-8, ASCII-16, Konami and Konami with SCC.
@@ Line 6: / Line 6: @@
 == Principles ==
-A mapped ROM is visible in pages 1 and 2 of the Z80 memory space (address 4000h-7FFFh and 8000h-BFFFh).<br/>
+A mapped ROM cartridge is visible to the Z80 through pages 1 and 2 of the memory space (address 4000h-7FFFh and 8000h-BFFFh).
-This 32 KB space is divided into either 4 '''banks''' (or sub-pages) of 8 KB or 2 banks of 16 KB.
+This 32 KB space is divided into either 4 '''banks''' (or sub-pages) of 8 KB, or 2 banks of 16 KB.
 This is why mappers are often categorized as 8 KB mapper and 16 KB mapper.
-ROMs using these mappers can be for example 128 KB, 256 KB, 512 KB, 1 MB, 2 MB or 4 MB in size (4 MB, only for 16 KB mapper).<br/>
+ROMs using these mappers can be for example 128 KB, 256 KB, 512 KB, 1 MB, 2 MB or 4 MB in size (4 MB, only for 16 KB mapper).
 The total content of the ROM is divided into blocks of the mapper size (8 or 16 KB). These blocks are called '''segments'''.
-The concept of using mappers is to associate a given segment with a bank to make it visible to the Z80.<br/>
+The concept of using mappers is to associate a given segment with a bank to make it visible to the Z80.
 By changing the segments visible in each bank during the course of the program, we can thus access the entire contents of the ROM.
@@ Line 24: / Line 24: @@
 === Change segment visbile through bank ===
-To change the visible segment in a bank, you just have to write the segment number to a given address (different depending on the mappers).<br/>
+To change the visible segment in a bank, you just have to write the segment number to a given address (different depending on the mappers).
 Write in a ROM, yes, you read it right!
-In fact, mapped ROMs have special mechanisms (mappers) that intercept write signals at certain addresses and use the written value to select the segment.<br/>
+In fact, mapped ROMs have special mechanisms (mappers) that intercept write signals at certain addresses and use the written value to select the segment.
 Using MSXgl, you don't need to know the addresses or write because you only need to use the <tt>SET_BANK_SEGMENT(bank, seg)</tt> macro which takes care of associating a segment to a bank.
 === Types of mappers ===

@@ Line 1: / Line 1: @@
-To create cartridges larger than 64 KB, {{MSXGL}} allows to use 6 types of ROM mappers. This documentation explain how to use the 4 classic ones: ASCII-8, ASCII-16, Konami, and Konami with SCC.
+To create cartridges larger than 64 KB, {{MSXGL}} allows to use several types of mapped-ROM (often called MegaROM).
-Most of the information also apply to [[NEO mapper]] (NEO-8 and NEO-16) but for further detail, see the dedicated section.
+This documentation primarily explains how standard mappers work: ASCII-8, ASCII-16, Konami and Konami with SCC.
 == Principles ==
@@ Line 20: / Line 21: @@
 ''128 KB ROM using an 8 KB mapper (ASCII-8) in slot 1. The ROM is composed of 16 segments, visible to the Z80 through 4 banks. In the example above, segment #0 is visible in bank #0, segment #1 in bank #1, segment #4 in bank #2 and segment #12 in bank #3.''
 </div>
 To change the visible segment in a bank, you just have to write the segment number to a given address (different depending on the mappers).<br/>
-Write in a ROM, yes, you read it right!<br/>
+Write in a ROM, yes, you read it right!
 In fact, mapped ROMs have special mechanisms (mappers) that intercept write signals at certain addresses and use the written value to select the segment.<br/>
 Using MSXgl, you don't need to know the addresses or write because you only need to use the <tt>SET_BANK_SEGMENT(bank, seg)</tt> macro which takes care of associating a segment to a bank.
 The supported mappers are:

@@ Line 177: / Line 177: @@
 === NEO mapper ===
-[[NEO mapper]] works on the same principle as the old mappers, but has more bank switching registers (covering page 0) and registers are 16-bit instead of 8-bit.
+[[NEO mapper]] works on the same principle as the legacy mappers, but has more bank switching registers (covering page 0) and registers are 16-bit instead of 8-bit.
 When your <tt>main()</tt> function start, the mapped-ROM cartridge slot is selected in pages #0, #1 and #2 of the memory space.

@@ Line 86: / Line 86: @@
 // Segment #5 (bank #3)
-u8 MyData[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
+const u8 MyData[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
 </syntaxhighlight>
@@ Line 93: / Line 93: @@
 // Main program
-extern u8 MyData[]; // Tell the compiler this data exists somewhere else.
+extern const u8 MyData[]; // Tell the compiler this data exists somewhere else.
 SET_BANK_SEGMENT(3, 5); // Switch segment visible through bank #3.

@@ Line 184: / Line 184: @@
 <img style="width:400px; margin:0.5em;" src="https://raw.githubusercontent.com/aoineko-fr/MSXgl/main/engine/doc/mapper_neo16.png" />
-NEO-8:
+Segment #4 of the NEO-8 and segment #2 of the NEO-16 have a special use: they are designed to be selected in bank #0, and the Build tool will automatically add an interrupt handling code (ISR) to them. This segment can be used to store code or data, but note that it will be accumulated from address 0x0100 (after the ISR).
 * Bank #0 (0000h-1FFFh): Segment #4 (contain the ISR)
 * Bank #1 (2000h-3FFFh): Segment #5
 * Bank #2 (4000h-5FFFh): Segment #0 (contain the ROM header)
@@ Line 192: / Line 196: @@
 * Bank #5 (A000h-BFFFh): Segment #3
-For 16 KB mappers:
+NEO-16
-* Bank #0 (0000h-3FFFh): Segment #2 (contain the ISR)
+* Bank #0 (0000h-3FFFh): Segment #2 (contain the ISR + user code/data after 0x0100)
 * Bank #1 (4000h-7FFFh): Segment #0 (contain the ROM header)
 * Bank #2 (8000h-BFFFh): Segment #1
+See the [[NEO mapper|NEO mapper specifications]] for more details about the mapper.
 === Yamanooto & ASCII16-X ===

@@ Line 27: / Line 27: @@
 The supported mappers are:
-{| class="wikitable"
+{{:Target/Mappers}}
 More details on the different mappers:

@@ Line 211: / Line 211: @@
 === Yamanooto & ASCII16-X ===
-Yamanooto and ASCII16-X are mapper that works like legacy mappers but allows more the 256 segments so they overcome their maximal size.
+Yamanooto and ASCII16-X are mappers that works like legacy mappers but allows more the 256 segments so they overcome their maximal size.
 Yamanoto:

← Older revision		Revision as of 23:36, 4 January 2025
Line 209:		Line 209:

	See the [[NEO mapper\|NEO mapper specifications]] for more details.		See the [[NEO mapper\|NEO mapper specifications]] for more details.
		+
		+	=== Yamanooto & ASCII16-X ===
		+	Yamanooto and ASCII16-X are mapper that works like legacy mappers but allows more the 256 segments so they overcome their maximal size.
		+
		+	Yamanoto:
		+	* Banks: 4 banks of 8 KB (visible on memory pages 1 and 2)
		+	* Size: up to 8 MB
		+	* Support: Yamanooto and openMSX
		+
		+	ASCII16-X:
		+	* Banks: 2 banks of 16 KB (visible on memory pages 1 and 2)
		+	* Size: up to 64 MB
		+	* Support: Incomming hardware and openMSX (8 MB)

	== Advice ==		== Advice ==

@@ Line 149: / Line 149: @@
 //-- List of raw data files to be added to final binary (array). Each entry must be in the following format: { offset:0x0000, file:"myfile.bin" }
 RawFiles = [
-     { segment: 2, file:"content/music1.vgm"},
+     { segment: 2, file: "content/music1.vgm"},
-     { segment: 3, file:"content/music2.vgm" },
+     { segment: 3, file: "content/music2.vgm" },
-     { offset: 0x18000, file:"content/image.bin" },
+     { offset: 0x18000, file: "content/image.bin" },
-     { page: 4, file:"content/video.bin" }
+     { page: 4, file: "content/video.bin" }
 ];
 </syntaxhighlight>