Difference between revisions of "NEO mapper/Extension"

Revision as of 19:27, 6 April 2026

⚠️ This page is still in the proposal stage and should not yet be considered an official specification.

Proposal for an extension to the NEO mapper format.

Any write operation to the NEO mapper with data bit 7 set to 1 and address bit 0 set to 1 is considered an access to extended features.

All other write operations should be considered normal access to the mapper's bank register.

The data contains:

The address contains an 8-bit parameter to be passed to the function.

ADDRESS
15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Page		Bank			0	0	Parameter								1

DATA
7	6	5	4	3	2	1	0
1	A	0	Function

When activated, any read access to the given bank will return the cartridge information (8 KB, mirrored on NEO-16).

PARAMETER
8	7	6	5	4	3	2	1
0	0	0	0	0	Bank

When activated, any read/write access to the specified bank (defined in the parameter) is redirected to the selected segment of the SRAM/FRAM.

SRAM/FRAM is accessed through 8 KB segments (on the NEO-16, the segment is mirrored).

Up to 16 segments can be accessed, for a total capacity of 128 KB.

PARAMETER
8	7	6	5	4	3	2	1
Segment				0	Bank

Activate or disactivate a device.

PARAMETER
8	7	6	5	4	3	2	1
0	0	0	0	Device

Devices:

@@ Line 93: / Line 93: @@
 Devices:
-* 0: MSX-Music
+* <tt>00</tt>: MSX-Music
-* 1: MSX-Audio
+* <tt>01</tt>: MSX-Audio
-* 2: SCC
+* <tt>02</tt>: SCC
-* 3: SCC+
+* <tt>03</tt>: SCC+
-* 4: OPL4
+* <tt>04</tt>: OPL4
-* 8: 2nd PSG (port 10h)
+* <tt>08</tt>: 2nd PSG (port 10h)
-* 9: Darky (2 x ePSG)
+* <tt>09</tt>: Darky (2 x ePSG)
-* 10: Darky Jr. (2 x PSG)
+* <tt>10</tt>: Darky Jr. (2 x PSG)
-* 12: SAM2695
+* <tt>12</tt>: SAM2695