1# segacd-core
2
3Sega CD / Mega CD emulation core.
4
5The Sega CD is a lot more than just a CD-ROM drive add-on. It's practically a second console that plugs into the Genesis through an expansion slot. It contains the following components:
6* 1x CD-ROM drive
7* Sanyo LC8951, a CD-ROM decoder & error correction chip
8* An additional 68000 CPU clocked at 12.5 MHz, about 63% faster than the Genesis 68000
9* Graphics ASIC that can perform hardware-accelerated image scaling and rotation
10* Ricoh RF5C164, an 8-channel PCM sound chip with 64KB of attached waveform RAM
11  * This is in addition to CD audio playback
12* 512KB of working/program RAM for the Sega CD 68000
13* 256KB of "word RAM" that can be exchanged between the two 68000s; meant primarily for data transfer from the Sega CD components to the Genesis components
14* 8KB of battery-backed RAM for storing save data, as well as support for an optional 128KB battery-backed RAM cartridge
15* 128KB BIOS mapped into the Genesis 68000's address space; contains a boot ROM and routines for controlling the CD-ROM drive
16* Lots of new registers, mostly for controlling the new components and for coordination between the two 68000s
17
18All of the Genesis components run in parallel with the new components, and all rendering is still performed using the Genesis VDP.
19 
20This crate contains code for the following:
21* CD-ROM file parsing and I/O
22* Sega CD's CD drive
23* LC8951 CD decoder chip
24* Sega CD's graphics ASIC
25* PCM sound chip
26* Sega CD memory map
27* Sega CD main loop