LHA-201, LHA-20B (Logitec)

Multi-vendor non-compliant C bus bus master SCSI-2 board.Even the main body of memory more than 16MB
Bus master transfer is possible.By using e10chk.exe which is a free software created by Mr. Marimo
I / O data IDE-to-SCSI conversion board HDX-SC-3 IOD1A067 (built in external HDD with 40GB
BIOS ROM 1.33 connected to the one) + Seagate ST3642A (6.4GB, without division by FAT32)
When the upper limit of recognition capacity of LHA-20B was examined, 63 BIOS sectors, 15 heads, and cylinders
Calculated as the number 13329 sector length 512 bytes, the result of no wall wall product of number of cylinders × number of heads
was gotten.
There are 4 8 dip switches and 2 3 jumper switches on the board (jumper switch
One of them is unused).

・ 8 series jumper switch SW1: SCSI_ID, interrupt level, DMA channel setting
1-2-3: SCSI_ID setting
　OFF-OFF-OFF: ID = 0
　ON-OFF-OFF: ID = 1
　OFF-ON-OFF: ID = 2
　ON-ON-OFF: ID = 3
　OFF-OFF-ON: ID = 4
　ON-OFF-ON: ID = 5
　OFF-ON-ON: ID = 6
　ON-ON-ON: ID = 7 (factory setting)
4-5-6: Interrupt channel setting
　OFF-OFF-OFF: INT0 (factory setting)
　ON-OFF-OFF: INT1
　OFF-ON-OFF: INT2
　ON-ON-OFF: INT3
　OFF-OFF-ON: INT5
　ON-OFF-ON: INT6
7-8: DMA channel setting
　OFF-OFF: DMA0
　ON-ON: DMA3 (factory setting)

・ 8-station dip switch SW2: Local memory address, setting of main unit model, presence of SCSI_BIOS access
1-2-3: Setting of local memory address in normal mode
　OFF-OFF-OFF: xD0000-xD0FFFh
　ON-OFF-OFF: xD2000-xD2FFFh
　OFF-ON-OFF: xD4000-xD4FFFh
　ON-ON-OFF: xD6000-xD6FFFh
　OFF-OFF-ON: xD8000-xD8FFFh
　ON-OFF-ON: xDA000-xDAFFFh
　OFF-ON-ON: xDC000-xDCFFFh (Factory default setting: Change prohibited)
　ON-ON-ON: xDE000-xDEFFFh
　※ "x" is "none", "0h", "0Fh"
4-5: Local memory address setting in high resolution mode
　OFF-OFF: xE8000-E8FFFh
　ON-OFF: xEA000-EAFFFh
　OFF-ON: xEC000-ECFFFh (Factory setting: Change prohibited)
　ON-ON: xEE000-EEFFFh
　※ "x" is "none", "0h", "0Fh"
6-7: Setting of machine model
　ON-ON: CPU is a V30 model
　OFF-ON: High-resolution mode compatible models (including those with high-resolution board mounted)
　ON-ON: Model in normal mode only
8: Access to SCSI_BIOS
　ON: accessible (factory setting)
　OFF: Not accessible (BIOS disconnected)

・ 8-station dip switch SW3: I / O base address, transfer mode setting
1-2: I / O base address setting
　ON-ON: 00C0 (Factory setting: Change prohibited)
　OFF-ON: 0CD0h
　ON-OFF: 0CE0h
　OFF-OFF: 0CF0h
3: Transfer mode setting
　ON: Mode automatic selection (bus master transfer) (Factory setting)
　OFF: I / O transfer fixed
　※ When used with PC-9821An, PC-9801RX, PC-H98 series, PC-H98S, PC-286 model 0
　　Only set it to OFF.
4-5-6-7-8: System use (Do not change.Factory setting: ON-ON-OFF-ON-OFF)

・ Three jumper switch SW5: Transfer mode setting
　1-2 short: DMA transfer fixed
　2-3 short: Mode automatic selection (Bus master transfer) (Factory setting: Change prohibited)

・ 8 stations dip switch SW6: Setting of main unit model
　ON-OFF-OFF-OFF-ON-OFF-ON-OFF: PC-9821Ae
　ON-OFF-ON-OFF-OFF-OFF-ON-OFF: PC-9821Bf, PC-9821Xa / Xn
　ON-OFF-OFF-ON-OFF-OFF-ON-OFF: PC-9801BX2, PC-9821Ce2
　ON-OFF-OFF-OFF-OFF-OFF-ON-OFF: Models other than the above (default settings)
* This switch is only for the pattern of LHA-20B owned by the author.