LC89515

Sanyo LC89515 chip found on a CDM3-2 board.

Sanyo CD-ROM host and error correction chip, also known as RCHIP. Used to load files in CD systems. It uses a 64KiB RAM buffer (2 32KiB RAM chips), which is able to store up to 27 CD-ROM sectors.

DMA copy speed from buffer to DRAMs can go up to 2.3MiB/s (16.9344MHz / 7 ?)

The NeoGeo CD does not use the C2 pointer error correction.

The NeoGeo CDZ uses the LC89513.

Datasheet

Complete datasheet: [[1]]

Pinout

Registers

Registers access is done through $FF0101 and $FF0103.

Read and writes auto-increments the register address except from register #0. After register #15, the address loops back to #0.

	Read		Write
#	Name	Definition	Name	Definition
0	COMIN	Command FIFO input (unused in NeoGeo CD ?)	SBOUT	Status byte output (unused in NeoGeo CD ?)
1	IFSTAT	Bit 7 6 5 4 3 2 1 0 Def /CMDI /DTEI /DECI 1 /DTBSY /STBSY /DTEN /STEN	IFCTRL	Bit 7 6 5 4 3 2 1 0 Def CMDIEN DTEIEN DECIEN /CMDBK /DTWAI /STWAI /DOUTEN /SOUTEN
2	DBCL	Data byte counter 8 LSBs
3	DBCH	Bit 7 6 5 4 3 2 1 0 Def DTEI Data byte counter 4 MSBs	DBCH	Bit 7 6 5 4 3 2 1 0 Def - Data byte counter 4 MSBs
4	HEAD0	SHDREN=0 SHDREN=1 Header minutes Subheader file #	DACL	Data start address 8 LSBs
5	HEAD1	SHDREN=0 SHDREN=1 Header seconds Subheader channel #	DACH	Data start address 8 MSBs
6	HEAD2	SHDREN=0 SHDREN=1 Header frames Subheader submode #	DTTRG	Any write triggers a transfer start
7	HEAD3	SHDREN=0 SHDREN=1 Header mode (01) Subheader coding info	DTACK	Any write acknowledges the transfer interrupt
8	PTL	Last decoded sector address 8 LSBs	WAL	Pointer to start of data to be loaded 8 LSBs
9	PTH	Last decoded sector address 8 MSBs	WAH	Pointer to start of data to be loaded 8 MSBs
10	WAL	Pointer to start of data to be loaded 8 LSBs	CTRL0	Bit 7 6 5 4 3 2 1 0 Def DCEN EDCRQ E01RQ AUTORQ ERAMRQ WRRQ QRQ PRQ
11	WAH	Pointer to start of data to be loaded 8 MSBs	CTRL1	Bit 7 6 5 4 3 2 1 0 Def SYIEN SYDEN DSCREN COWREN MODRQ FORMRQ - SHDREN
12	STAT0	Bit 7 6 5 4 3 2 1 0 Def CRCOK ILSYNC NOSYNC LBLK WSHORT SBLK ERABLK UCEBLK	PTL	Pointer to start of data to be decoded 8 MSBs
13	STAT1	Bit 7 6 5 4 3 2 1 0 Def MINERA SECERA BLKERA MODERA SH0ERA SH1ERA SH2ERA SH3ERA Error flags for HEAD0~HEAD3	PTH	Pointer to start of data to be decoded 8 LSBs
14	STAT2	Bit 7 6 5 4 3 2 1 0 Def - MODE FORM -	Unused
15	STAT3	Bit 7 6 5 4 3 2 1 0 Def /VALST WLONG -	RESET

Notes

If CD command FIFO is not empty, status FIFO[1] = 15 (busy ?).

• Command 0: Nop ?
• Command 1:

CDEmuStop();
NeoCDAssyStatus = 0x0E;

• Command 2:

status FIFO[1]=command FIFO[3]

• • 0: Read Q subcode first 6 digits

Data in FIFO[2~7] & FIFO[8]

• • 1: Read Q subcode next 6 digits

Data in FIFO[2~7] & FIFO[8]

• • 2: Read Q subcode last 2 digits

Data in FIFO[2~3] & FIFO[8]

• • 3: Read subcode TOC -2?

Data in FIFO[2~7]

• • 4: Read subcode TOC -1?

Data in FIFO[2~5]

• • 5: Read TOC from track in FIFO[4~5]

Data in FIFO[2~7] & FIFO[8]

// bit 3 of the 1st minutes digit indicates a data track
if (TOCEntry[3] & 4) {
	NeoCDCommsStatusFIFO[6] |= 8;
}

• • 6: Read Q subcode status ?

Data in FIFO[8] only

• • 7: Clear FIFO ?

FIFO[3] = 5

• 3: Switch mode according to reg. #10 bit 2

MSF set in FIFO[2~3]. Starts reading disc.

• 4: Pasue
• 5:

NeoCDAssyStatus = 4;
bNeoCDLoadSector = false;

• 7:

NeoCDAssyStatus = 1;
bNeoCDLoadSector = true;