2-14
2.1.4 BIOS
ROM
A flash memory of 512K
×
8 bits is used for the BIOS.
ROM’s address decoding is undertaken by the chip set. The BIOS setting area is 000E0000h
~
000FFFFFh or FFFE0000h
~
FFFFFFFFh that is the most significant area for the CPU. (Either address can be accessed.)
When used as a 512K type, continuous access becomes possible in the virtual memory area.
The flash memory is a write-enabled memory that requires command control by software when writing.
The BIOS ROM data bus is connected to the X bus since ROM’s fan-out is small. It is then connected to the system data bus
(SD bus) via the buffer (HCT245).
Since this system uses the shadow memory method, the contents of ROM are written in the main memory when the BIOS is
started. After the system has been started, the CPU disconnects the ROM and works with the RAM.
The shadow memory method is effective to raise the processing speed by performing system’s operation with the RAM the
access speed of which is higher than that of the ROM. It is possible to separate the programs that are not required in other cases
than system start. As a result, the work area can be expanded.
Summary of Contents for JS-170FR Series
Page 2: ......
Page 10: ......
Page 30: ...1 20 ...
Page 80: ...2 50 ...
Page 101: ...3 17 LCD DISPLAY TEST 6 Video Test ENTER 1 OK or 2 NG ...
Page 134: ...4 JS 170FR PCB s 4 1 Main PCB 4 1 1 Main PCB Schematic Diagram 1 10 4 1 ...
Page 135: ...4 1 1 Main PCB Schematic Diagram 2 10 4 2 ...
Page 136: ...4 1 1 Main PCB Schematic Diagram 3 10 4 3 ...
Page 137: ...4 1 1 Main PCB Schematic Diagram 4 10 4 4 ...
Page 138: ...4 1 1 Main PCB Schematic Diagram 5 10 4 5 ...
Page 139: ...4 1 1 Main PCB Schematic Diagram 6 10 4 6 ...
Page 140: ...4 1 1 Main PCB Schematic Diagram 7 10 4 7 ...
Page 141: ...4 1 1 Main PCB Schematic Diagram 8 10 4 8 ...
Page 142: ...4 1 1 Main PCB Schematic Diagram 9 10 4 9 ...
Page 143: ...4 1 1 Main PCB Schematic Diagram 10 10 4 10 ...
Page 144: ...4 1 2 Main PCB Parts Location 4 11 ...
Page 145: ...4 2 MB PCB 4 2 1 MB PCB Schematic Diagram 4 17 ...
Page 146: ...4 18 4 2 2 MB PCB Parts Location ...
Page 148: ...4 3 Peripheral PCB 4 3 1 Peripheral PCB Schematic Diagram 4 20 ...
Page 149: ...4 21 4 3 2 Peripheral PCB Parts Location ...
Page 152: ...5 2 Main PCB 75 Peripherals ...
Page 153: ...5 3 Power Supply Peripherals ...
Page 154: ...5 4 Customer Display Peripherals ...
Page 155: ...5 5 LCD Peripherals ...
Page 156: ...5 6 Inverter PCB Peripherals ...
Page 161: ...Printed in Japan ...