This is the detailed technical description and documentation for the multi-functional Carnivore2 cartridge that was created by RBSC.

NOTE: The hexadecimal numbers are shown as #90, 90h or 0x90

The main components and features:

• External storage: CF card (CompactFlash)
  • Nextor is used as DOS (built-in support for FAT12/16, maximum partition size: 4 GB)
  • High read and write speeds
  • Supports SD and MicroSD card adapters
  • Nextor supports floppy disk emulation with DSK files
  • Utilities compatible with MSX-DOS versions 1 and 2
  • The cartridge can be configured as a RAM extension, IDE disk, FMPAC and SCC/SCC+ sound cards, or a combination of these devices
• RAM: 2048 KB (2 MB)
  • Includes:
    • 1024 KB main RAM with mapper
    • 256 KB for ROM shadowing
    • 720 KB additional RAM with a mapper, similar to MegaRAM
    • 4 KB FMPAC SRAM (a backup battery is needed to save data after turning off the power)
• Flash memory (FlashROM): 8 MB capacity, 64 Mbit/s
  • The first 256 KB are used for service information and ROM BIOSes
  • Mapper emulation:
    • Linear 64 KB mode
    • ASCII8
    • ASCII16
    • Konami4
    • Konami5 (SCC/SCC+)
    • Custom mapper
• Sound
  • PPI and PSG emulation
  • Konami SCC and SCC+ emulation
  • OPLL emulation (YM2413, MSX – Music), BIOS UI translated to English
  • Volume setting for all emulated audio devices
  • PSG and PPI can be enabled and disabled in the user interface
• Additional 128 byte configuration EEPROM (M93C46MN1), works in 8–bit mode
• User–adjustable volume for SCC and FMPAC (8 steps), saved in 93C46 EEPROM
• User–adjustable volume for PSG and Clicker (8 steps), saved in 93C46 EEPROM
• User–controlled PSG and Clicker device on/off switch
• User–adjustable VDP frequency (50/60Hz), saved in the 93C46 EEPROM

On–board BIOSes and modules:

The location of the Boot Menu, directory and BIOSes in the FlashROM chip is described below. There are logical and physical blocks and they have different numbering.

The FlashROM chip that is used in Carnivore2 has 8 logical blocks in the first physical 64 KB block and then go the rest of 64 KB physical blocks. In the logical blocks there are Boot Menu and directory. The next few blocks are allocated for the BIOSes of the embedded devices.

The first 8 logical 8 KB blocks are grouped into the first physical block that is addressed by the AddrFr register. Logical blocks 0, 1, 6 and 7 contain the Boot Menu's code and data. Blocks 2 and 3 contain directory entries. Then go 2 blocks that are reserved for future use.

After the first 8 logical 8 KB blocks that form the first physical block, there go the physical 64 KB blocks of the FlashROM.

Model: Numonix M29W640GB TSOP48
Datasheet

Block layout:

Command addresses: #4555 and #5AAA

Commands:

FlashROM ID: #7E

• Block 0 is reserved for the directory and the boot menu: BOOTCMFC.BIN
• Blocks 1–2 are reserved for the IDE BIOS: BIDECMFC.BIN
• Block 3 is reserved for the FMPAC BIOS: FMPCCMFC.BIN

The OPLL emulation (FMPAC) that is supported by the cartridge is mapped to ports #7C–7D.

The FMPAC SRAM is emulated by using the 8 KB of the upper area of the 1st megabyte of RAM (shadow RAM) that is not shared with the memory mapper. The physical address of the 8 KB area for SRAM in the shadow RAM is 0FE000h–0FFFFFh.

NOTE: The settings of SRAM will be lost after powering down unless the cartridge has the backup battery installed.

FMPAC's own control registers:

• 7FF4h: write YM-2413 register port (write only)
• 7FF5h: write YM-2413 data port (write only)
• 7FF6h: activate OPLL I/O ports (read/write)
• 7FF7h: ROM page (read/write)

To enable 8 KB of SRAM at address 4000h–5FFFh, set 4Dh to 5FFEh and 69h to 5FFFh.

Model: M93C46MN1 (128 bytes/1 Kbit)
Datasheet

IMPORTANT! The chip is operated only in 8–bit mode!

This EEPROM is used to store additional configuration settings. Using the EEPROM prevents the important configuration settings from being lost after power goes down. The location of the settings in the EEPROM and their description can be found i the table blow.

Writing to EEPROM is done via the configuration register CardMDR+#23. The commands for EEPROM are saved into this register in a sequence that is described in the chip's datasheet. Only write–enable, read and write commands are used.

The configuration registers are located at addresses #0F80 or #4F80 or #8F80 or #CF80h. Their visibility and location is controlled by the main control register's first byte — at address #4F80. The main control register is called CardMDR. After power on, the registers are located at address #4F80. All registers are write–only except the pseudo–register for sending/receiving the data when accessing the FlashROM and the register for the configuration EEPROM, as well as 3 bytes of the firmware version - FPGA_ver.

Below you can find the description of configuration registers.

There are six bank configuration registers:

1. RnMask
2. RnAddr
3. RnReg
4. RnMult
5. BnMaskR
6. BnAdrD

n — this is the bank number.

Bitmask for bank's register address. This value is normally mirrored into several addresses, for example for Konami 5 cartridges those addresses for the first bank are 5000h–57FFh. Here we use only the high byte's address — F8h (11111000b).

The default value of this register is F8h

High byte of the bank's address register (example: 50h for address 5000h)

The default value of this register is 50h.

Initial value for bank's number (usually 00h)

The default value of this register is 00h.

RnMult — bank's mode and size register

The default value is 00h (bank is disabled)

Bitmask for bank's addressing mode into the FlashROM. This is the ROM's emulated size and the number of pages. For example for a 128 KB ROM we will need 16 pages of 8 KB, so we set the 0Fh (00001111b) mask.

The default value of this register is 03h

High byte of the bank's address (example: 40h for address 4000h).

The default value of this register is 40h

00 CardMDR — main cartridge's configuration register

1E Mconf — expanded slot configuration register

There are 253 user–controlled directory entries available in the cartridge. The first directory entry can't be edited or deleted because it sets the default cartridge's configuration — all enabled. The directory is 8 KB in size and is located in the 2 and 3 logical blocks of the FlashROM chip at addresses 004000h–005FFFh (block 2) and 006000h–007FFFh (block 3). The physical block number (controlled by the AddrFr register) is zero.

Each directory entry occupies 40h (64 bytes) and has the following format:

PosSiz — size and position in 64 KB block for mini ROMs

RstRun — reset and start options

The cartridge supports a few common mappers and the linear mode that allows first 64 KB of the MiniROM to be visible in the address space. The physical addresses allocated for the mappers' operation lie in the range of 100000h–1FFFFFh. This means that only the second megabyte of RAM is used.

Mappers type values:

The cartridge supports the ASCII8 mapper.

Default configuration values:

The cartridge supports the ASCII16 mapper.

Default configuration values:

The cartridge supports the Konami4 mapper.

Default configuration values:

The cartridge supports the Konami5 (SCC) mapper.

Default configuration values:

The cartridge supports MiniROM (ROM images up to 49 KB) without mapper.

Default configuration values:

The cartridge supports the linear 64 KB mode, when the first 64 KB of the ROM are visible in the address space.

The default configuration values for MiniROMs are:

Bank addresses in linear mode:

Below you can find the default values for several configuration registers.

RCP file format description.

Carnivore2 can be detected and controlled via its own configurable port #F0-F2. The following I/O operations are possible:

1. Detection of the cartridge
   • Write “C” to port, then read the value. Carnivore2 will respond with its version - “2” (ASCII format)
2. Identify the slot used by Carnivore2
   • Write “S” to port, then read the value. Carnivore2 will respond with its slot, for example “1” (ASCII format)
3. Hide control registers
   • Write “H” to port, the control registers will be hidden
4. Show control registers
   • Write “R” to port, control the registers will appear at their defined location (see below)
5. Set location for control registers
   • Write “0” to port, the control registers will appear at #0F80
   • Write “1” to port, the control registers will appear at #4F80
   • Write “2” to port, the control registers will appear at #8F80
   • Write “3” to port, the control registers will appear at #CF80
6. Set cartridge's device configuration (software reset is required!)
   • Write “A” to port, the cartridge will enable only the main slot (one device only)
   • Write “M” to port, the cartridge will set the default configuration (all devices enabled)

Carnivore2 User Guide