PC-9801-55U (NEC)

C bus SCSI I / F. SCSI connector is Amphenol half 50 pin.
When connecting an HDD for NEC check of ROM, the first vendor name
If the three letters do not begin with NEC (NEC, NECTSU, NECTOR, etc.),
Beeps continuously and does not start the body by entering an infinite loop.
When connecting a cassette magnetic tape unit, I / O with other SCSI devices
To separate F (two boards required).
There are 2 8 dip switches and 2 3 jumper switches on the board.

· 8 stations dip switch SW1: SCSI ID number of the board, interrupt level,
　DMA channel setting
1-2-3: Set board SCSI ID number
　ON-ON-ON ID 7 (Factory setting)
4-5-6: Setting interrupt level
　OFF-OFF-OFF ■ INT 0
　ON-OFF-OFF INT 1
　OFF-ON-OFF INT 2
　ON-ON-OFF INT 3 (default setting)
　OFF-OFF-ON INT 5
　ON-OFF-ON INT 6
7-8: DMA channel setting
　OFF-OFF DMA # 0 (factory setting)
　ON-OFF ■ Setting prohibited
　OFF-ON DMA # 2
　ON-ON DMA # 3

・ 8 stations dip switch SW2: ROM memory address, body model, Power on
　ROM accessibility setting at the time of
1-2-3-4-5-6-7: Setting ROM memory address + main unit model
　　　　　　　　　　　　(Factory setting: OFF-ON-ON-OFF-ON-ON-OFF)
(1) PC-98XA (high res dedicated machine)
　xxx-OFF-ON-OFF-OFF ■ Memory address \ EC 000 h ~ \ EDFFF h
(2) 8086 loading machine
　OFF-ON-OFF-xx-ON-OFF ■ Memory address D4000h to D5FFFh
(3) V30 loading machine
　OFF-ON-ON-xx-ON-OFF ■ Memory address DC000h to DDFFFh
(4) Normal / high res combined use machine
　OFF-ON-ON-OFF-ON-OFF-ON
(5) The machine with an 80286/386/486 (only for normal mode)
　OFF-ON-ON-xx-ON-ON ■ Memory address \ DC 000 h ~ \ DDFFF h
※ x can be set to ON or OFF, and \ means 0h or Fh.
※ When used with B4670 II (PC-9864L / PC-9864U) in high resolution mode,
　OFF-ON-ON-ON-ON-OFF-OFF (PC-98XA) or OFF-ON-ON-ON-ON-ON-OFF-ON
(Normal / high res combined use machine)
※ The combination with GP-IB interface board is not possible with the 8086 installed machine.
8: Setting of ROM accessibility at Pow on
　ON ■ ROM accessible (factory setting)
　OFF ■ ROM can not be accessed

・ Three jumper switches SW3 and SW4: I / O port address setting
Below, short pin at SW3 ■ Short pin at SW4 ■ I / O port address
Order of:
　01-02 ■ 01 02 ■ CC0h, CC2h, CC4h (factory setting)
　02-03 ■ 01 02 ■ CD0h, CD2h, CD4h
　01-02 ■ 02 03 ■ CE0h, CE2h, CE4h
　02-03 ■ 02 03 ■ CF 0 h, CF 2 h, CF 4 h
※ Except when the cassette magnetic tape unit is connected, use with the factory setting.
　Also, when changing to settings other than the factory settings, turn off SW2-8.

When used on an 8086 / V30 machine, the switch beside the card edge connector
Make the pin lever point up.