Electronics > Repair
What more i can do?
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amyk:
This appears to be a PC-98 compatible system, based on the boot sector code at the beginning of the ROM image. There's very little detailed technical information in English about them online, as it's a Japanese-native platform. Here's a useful reference I came across trying to figure out why the boot sector was using INT 1B seemingly to read the rest of the ROM disk (use translator): http://radioc.web.fc2.com/column/pc98bas/bios/disk.htm
222Lab_Test222:

--- Quote from: fzabkar on December 16, 2024, 07:16:11 am ---
The FDC37C661 device is a 2.88MB Super I/O Floppy Disk Controller with a parallel port, 2 x serial ports and an IDE interface.

https://theretroweb.com/chip/documentation/fdc37c661-6419cedba3e3f070037826.pdf (datasheet)

--- End quote ---
The Disk here, what is it trying to represent.
I mean is there anything similiar to 100 Pin IC in motherboard. I think nope.
fzabkar:
BIOS structure


--- Code: ---0x0000 - 0x1FFF  -- mostly empty, file header
0x2000 - 0x2FFF  -- 3mode FD-BIOS KDX4.1.34 for FDC37C661  by WACOM 1997.04  Rev.Sun&Moon
0x3000 - 0x3FFF  -- ROM disk XBIOS KDX4.1.30 1995.12 SUN
0x4000 - 0x4FFF  -- PCD BIOS Ver2.03 Copyright 1997 WACOM Engineering Co., Ltd.
0x5000 - 0x5FFF  --
0x6000 - 0x98FF  --
0x9900 - 0xD1FF  --
0xD200 - 0xD4FF  --
0xD500 - 0xEFFF  -- XBIOS 1.00 1995    PCMCIA Socket Service 2.10, Driver Rev 1.01, Copyright WACOM Engineering 1996.01
0xF000 - 0xF7FF  --
0xF800 - 0xFFFF  -- KDX.1.34A Copyright 1993,¥¥,97 WACOM
--- End code ---

On power-up, the BIOS jumps to 0xF000 in KDX.SYS and begins POST-ing.

I have used DEBUGX to disassemble the code. Offset 0x100 in the listing equates to offset 0xF800 in KDX.SYS.

If a particular test fails, it results in a CPU halt (HLT). There does not appear to be a diagnostic port.

This is the first test:


--- Code: ---0C1E:0119 66C1E210          SHL     EDX,10
0C1E:011D B044              MOV     AL,44
0C1E:011F E611              OUT     11,AL
0C1E:0121 B092              MOV     AL,92
0C1E:0123 E637              OUT     37,AL
0C1E:0125 B00F              MOV     AL,0F
0C1E:0127 E637              OUT     37,AL
0C1E:0129 B00B              MOV     AL,0B
0C1E:012B E637              OUT     37,AL
0C1E:012D B000              MOV     AL,00
0C1E:012F E65F              OUT     5F,AL
0C1E:0131 E652              OUT     52,AL
0C1E:0133 BA7100            MOV     DX,0071
0C1E:0136 BB1000            MOV     BX,0010
0C1E:0139 B90300            MOV     CX,0003
0C1E:013C B4FF              MOV     AH,FF
0C1E:013E 8AC3              MOV     AL,BL
0C1E:0140 E677              OUT     77,AL
0C1E:0142 EB00              JMP     0144
0C1E:0144 8AC4              MOV     AL,AH
0C1E:0146 EE                OUT     DX,AL
0C1E:0147 EB00              JMP     0149
0C1E:0149 8AC7              MOV     AL,BH
0C1E:014B E677              OUT     77,AL
0C1E:014D EB00              JMP     014F
0C1E:014F EC                IN      AL,DX
0C1E:0150 EB00              JMP     0152
0C1E:0152 3AC4              CMP     AL,AH
0C1E:0154 7501              JNZ     0157
0C1E:0156 F4                HLT
--- End code ---
222Lab_Test222:

--- Quote from: fzabkar on December 16, 2024, 08:37:03 am ---BIOS structure


--- Code: ---0x0000 - 0x1FFF  -- mostly empty, file header
0x2000 - 0x2FFF  -- 3mode FD-BIOS KDX4.1.34 for FDC37C661  by WACOM 1997.04  Rev.Sun&Moon
0x3000 - 0x3FFF  -- ROM disk XBIOS KDX4.1.30 1995.12 SUN
0x4000 - 0x4FFF  -- PCD BIOS Ver2.03 Copyright 1997 WACOM Engineering Co., Ltd.
0x5000 - 0x5FFF  --
0x6000 - 0x98FF  --
0x9900 - 0xD1FF  --
0xD200 - 0xD4FF  --
0xD500 - 0xEFFF  -- XBIOS 1.00 1995    PCMCIA Socket Service 2.10, Driver Rev 1.01, Copyright WACOM Engineering 1996.01
0xF000 - 0xF7FF  --
0xF800 - 0xFFFF  -- KDX.1.34A Copyright 1993,¥¥,97 WACOM
--- End code ---

On power-up, the BIOS jumps to 0xF000 in KDX.SYS and begins POST-ing.

I have used DEBUGX to disassemble the code. Offset 0x100 in the listing equates to offset 0xF000 in KDX.SYS.

If a particular test fails, it results in a CPU halt (HLT). There does not appear to be a diagnostic port.

This is the first test:


--- Code: ---0C1E:0119 66C1E210          SHL     EDX,10
0C1E:011D B044              MOV     AL,44
0C1E:011F E611              OUT     11,AL
0C1E:0121 B092              MOV     AL,92
0C1E:0123 E637              OUT     37,AL
0C1E:0125 B00F              MOV     AL,0F
0C1E:0127 E637              OUT     37,AL
0C1E:0129 B00B              MOV     AL,0B
0C1E:012B E637              OUT     37,AL
0C1E:012D B000              MOV     AL,00
0C1E:012F E65F              OUT     5F,AL
0C1E:0131 E652              OUT     52,AL
0C1E:0133 BA7100            MOV     DX,0071
0C1E:0136 BB1000            MOV     BX,0010
0C1E:0139 B90300            MOV     CX,0003
0C1E:013C B4FF              MOV     AH,FF
0C1E:013E 8AC3              MOV     AL,BL
0C1E:0140 E677              OUT     77,AL
0C1E:0142 EB00              JMP     0144
0C1E:0144 8AC4              MOV     AL,AH
0C1E:0146 EE                OUT     DX,AL
0C1E:0147 EB00              JMP     0149
0C1E:0149 8AC7              MOV     AL,BH
0C1E:014B E677              OUT     77,AL
0C1E:014D EB00              JMP     014F
0C1E:014F EC                IN      AL,DX
0C1E:0150 EB00              JMP     0152
0C1E:0152 3AC4              CMP     AL,AH
0C1E:0154 7501              JNZ     0157
0C1E:0156 F4                HLT
--- End code ---

--- End quote ---

Put in non working EPROMS? High or Low?
Can you make .BIN file?
squadchannel:
worked ROM and the didn't work ROM are exactly the same binary.
the problem is not in the ROM but still elsewhere. therefore, replacing the ROM will not change anything.

Is it an RTC, is there more to it, or can it be cured with a magic finger like in curiousMarc's PS/2 repair video? 8) I don't know. :-//

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