Technical information

SEGA Confidential
6
3.0 Setting the Jumper Pins
The VCD I/F Board has four jumper pins:
• ISA-IRQ setting (J3) • ISA-DMA setting (J4)
• I/O address setting (J5) • Diag setting (J6)
If the IRQ, DMA, and I/O address settings above conflict with those already set on
your PC, the Virtual CD may not start or the PC may hang up.
Be sure to fully understand each PC setting before changing the VDP I/F board
settings, and then change the board settings only if the default settings would cause
problems—for example, if the settings conflicted with those of the SCSI board DMA
channel. In such a case, the system configuration parameters would also need to be
modified. However, if the board is installed with default settings set at the factory,
the system configuration parameters do not need to be changed. For more informa-
tion on system startup procedures, see section 5.1, Preparing to Start.
1) ISA-IRQ Setting (J3)
Interrupt request numbers for the PC are selected via jumper pin settings. The de-
fault is set to IRQ10.
Pin 1-2 IRQ4(00)
Pin 3-4 IRQ3(01)
Pin 5-6 IRQ10(02)
Pin 7-8 IRQ11(03)
Pin 9-10 IRQ12(04)
Pin 11-12 IRQ15(05)
2) ISA-DMA Setting (J4)
The DREQ and DACK signal numbers for transfers between the PC and DMA are
also selected via jumper pin settings.
The default is set to DREQ5/DACK5.
Pin 1-2 & 3-4 DREQ5/DACK5(00)
Pin 5-6 & 7-8 DREQ6/DACK6(01)
Pin 9-10 & 11-12 DREQ7/DACK7(02)
3) I/O Address Setting (J5)
The I/O address of the VCD I/F Board is selected in a simular manner. The default
is set to 340H.
Pin 1-2 & Pin 3-4 & Pin 5-6 340H(00)
Pin 3-4 & Pin 5-6 350H(01)
Pin 1-2 & Pin 5-6 3E0H(02)
Pin 5-6 300H(03)
Pin 1-2 & Pin 3-4 310H(04)
Pin 3-4 320H(05)
Pin 1-2 330H(06)
Open 370H(07)
(J6) Diag setting function of (J6) is used at the factory during manufacturing. This
is left open.