LC89515

From NeoGeo Development Wiki
Jump to: navigation, search
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 Chipicon.png LC89513.

Datasheet

Complete datasheet: [[1]]

Pinout

Lc89515.png

Registers

Registers access is done through Reg.png $FF0101 and Reg.png $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/DECI1/DTBSY/STBSY/DTEN/STEN
IFCTRL
Bit 7 6 5 4 3 2 1 0
Def CMDIEN DTEIENDECIEN/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 EDCRQE01RQAUTORQERAMRQWRRQQRQPRQ
11 WAH Pointer to start of data to be loaded 8 MSBs CTRL1
Bit 7 6 5 4 3 2 1 0
Def SYIEN SYDENDSCRENCOWRENMODRQFORMRQ-SHDREN
12 STAT0
Bit 7 6 5 4 3 2 1 0
Def CRCOK ILSYNCNOSYNCLBLKWSHORTSBLKERABLKUCEBLK
PTL Pointer to start of data to be decoded 8 MSBs
13 STAT1
Bit 7 6 5 4 3 2 1 0
Def MINERA SECERABLKERAMODERASH0ERASH1ERASH2ERASH3ERA

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 - MODEFORM-
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;