Author Topic: What more i can do?  (Read 36925 times)

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Offline m k

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Re: What more i can do?
« Reply #450 on: December 13, 2024, 09:02:28 am »
Yes.
Afterwards Harry can do his trick and then we'll see how data has changed.

Harry, if second data is E9 check also to where it is actually jumping.
Previous data indicates that address will be F8E9.

68k CPU has a special 8 bit write cycle, it doubles one side of 16 bit data.
Controller chip can have a mode something like that.

But it also means that OE is not activated.
Or something is forcing that other side of data bus.
Or there is a latch.
Or something else.
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
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Offline asis

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Re: What more i can do?
« Reply #451 on: December 14, 2024, 04:29:43 am »
Hello,

@222Lab_Test222

I analyzed the content of this thread and out of more than 450 replies, as it turned out, 25% directly or indirectly boiled down to an attempt to understand the behavior of IC23 (NEC uPD4990A) CMOS.

All those participating in the discussion sometimes came very close to understanding the truth.

All the possibilities were determined only by the presence of a two-channel scope.
But, believe me, it is very difficult to perceive the processes occurring in the product from the pictures on the scope screen, with so many components and, let's say, turning the scope into a signature analyzer or Curve Tracer.
-
I would like to offer you an idea.
-
As you can see, there are six quartz generators on the PCB, servicing various nodes.
All together they must interact - as a single organism.
Figuratively speaking, - all hearts must beat in a single rhythm.
-
Now to the point.
I want to draw your attention to the Clock 32768kHz (X1 - IC7 74ACT08).
Or, more precisely, to C10.
I doubt that it is installed for time correction (in the sense of GLOBAL/UTC).
As a rule, the accuracy is sufficient wherever the 32768kHz quartz is used.
I suspect that the C10 adjustment determines some kind of "global synchronization" that optimizes timings in conjunction with other nodes, including  IC23 (NEC uPD4990A) CMOS.
The presence of checkpoints TP1, TP2 convinces me of this even more.
-
I offer you - such a scenario:

On a non-working board, you find a pin on IC7 (74ACT08), measure and write down the original frequency so that you can return to the original state ( check TP1, TP2).
And start adjusting C10, carry out the delta F deviation to a larger, and then (!), to a smaller value, fixing it all together.
That is, I suggest you find a range of acceptable values, in which IC23 (NEC uPD4990A) will work stably.
Perhaps, this will be facilitated by the LED indication and the buzzer reaction.
If everything works out, set C10 to the average frequency value in a certain interval.
You will probably have to turn the device on/off several times.
But, if we go back in time, all old PCs had a priority of devices, starting with KBD and ending with CD / HDD, etc.
If you have KBD, then the easiest way to create NMI is Ctrl - Alt - Del.
You may have a different combination.
But it should be.

Good luck.
 
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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #452 on: December 16, 2024, 02:14:57 am »
@Harry_22
@fzabkar

Here are the EPROS Datas
4 Datas are there.
Working High, Working Low, Non Working High and Non Working Low
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #453 on: December 16, 2024, 04:25:38 am »
On a non-working board, you find a pin on IC7 (74ACT08), measure and write down the original frequency so that you can return to the original state ( check TP1, TP2)
TP1 is shorted with PIN 11 of IC23 uD49.
TP2 is shorted with GND.

I still couldn't find the PIN on IC7 for frequency. Those IC7 Pins are either connected to IC6 or IC3 or Flash Memory.
Did i miss something?
 

Offline squadchannel

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Re: What more i can do?
« Reply #454 on: December 16, 2024, 04:49:43 am »
interleaved at single byte. (attached)
no difference in comparison. probably a hardware failure.  :-BROKE
 
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Offline squadchannel

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Re: What more i can do?
« Reply #455 on: December 16, 2024, 05:02:16 am »
can mount it with imdisk. :box:

« Last Edit: December 16, 2024, 05:10:16 am by squadchannel »
 
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Offline squadchannel

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Re: What more i can do?
« Reply #456 on: December 16, 2024, 05:30:37 am »
two EPROMs are just system drives; the CGROM is a character ROM.
so assuming there are no other ROMs, I would consider TORNADO a chipset designed to run only the boot sector of the EPROMs.

yep, no BIOS or anything.


found BIOS in $70000...?

 ;D
« Last Edit: December 16, 2024, 05:45:26 am by squadchannel »
 

Offline fzabkar

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Re: What more i can do?
« Reply #457 on: December 16, 2024, 06:55:29 am »
KDX.SYS is the 64KiB BIOS (0x70000 - 0x7FFFF). Its 8-bit checksum is 0x00.

Code: [Select]
end of EPROM = end of KDX.SYS, so KDX.SYS is the BIOS.

Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

0007FE70  FC 2E AD AB 0C 80 AB E2 F8 C3 16 42 49 4F 53 20  ü..«.€«âøÃ.BIOS
0007FE80  CA DE B0 BC DE AE DD 20 4B 44 58 2E 31 2E 33 34  ÊÞ°¼Þ®Ý KDX.1.34  <-- WACOM KDX.1.34 BIOS
0007FE90  41 1C 43 6F 70 79 72 69 67 68 74 20 31 39 39 33  A.Copyright 1993
0007FEA0  2C A5 A5 2C 39 37 20 57 41 43 4F 4D 20 20 17 2B  ,¥¥,97 WACOM  .+
0007FEB0  20 4D 45 4D 4F 52 59 20 28 30 30 30 30 30 2D 31   MEMORY (00000-1
0007FEC0  46 46 46 46 29 20 0E 2B 20 56 52 41 4D 20 4D 45  FFFF) .+ VRAM ME
0007FED0  4D 4F 52 59 20 1A 2B 20 45 58 54 45 4E 44 45 44  MORY .+ EXTENDED
0007FEE0  20 4D 45 4D 4F 52 59 20 30 30 30 30 30 4B 42 20   MEMORY 00000KB
0007FEF0  10 2B 20 49 4E 49 54 49 41 4C 49 5A 45 20 4F 4B  .+ INITIALIZE OK
0007FF00  21 79 04 0F 00 05 37 05 39 05 46 05 60 05 47 05  !y....7.9.F.`.G.
0007FF10  23 05 39 05 2F 04 2C 04 22 04 6A 04 5E 04 3B 04  #.9./.,.".j.^.;.
0007FF20  73 01 23 79 04 10 00 05 61 05 62 05 6A 05 39 05  s.#y....a.b.j.9.
0007FF30  24 05 43 05 41 04 4E 26 62 2D 46 04 2C 29 54 20  $.C.A.N&b-F.,)T
0007FF40  35 04 47 04 39 01 23 20 5B 42 38 45 4E 44 5D 00  5.G.9.# [B8END].
0007FF50  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FF60  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FF70  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FF80  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FF90  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FFA0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FFB0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FFC0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FFD0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FFE0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0007FFF0  E9 0D F8 00 00 00 00 00 00 00 00 00 00 00 DC C8  é.ø...........ÜÈ  <-- Intel 80486 boots from here

The file system has an unusual sector size of 1024 bytes with 1 sector per cluster.

FAT boot sector

Code: [Select]
 LBA:0                  block: 0

 OEM identifier   "(.9SFIHC       "
 Bytes per Sector  1024
 Sectors per Clust 1
 Reserved Sectors  1
 Number of FATs    2
 Root Dir Entries  192
 Total Sectors     512
 Media Descriptor  hE
 Sectors per FAT   2
 Sectors per Track 8
 Number of Heads   2
 Hidden Sectors    0
 Total Sectors     0
 (0x00800080)      00000000h
 Tot. NTFS Sectors 562997198454784
 MFT Cluster       10376293541461622784
 MFT Mirr Cluster  2314937383425933312
 Clusters per FILE 538976288           (0 bytes)
 Clusters per INDX 1297307987          (0 bytes)
 Serial Num (hex)  534F4453-53202020h
 Checksum          6F4E5359h
 Boot Sign (0xAA55)0000h

Root directory

Code: [Select]
 LBA:10                 block: 10

    name  ext       size   cluster attrs    modified            created                accessed
-------------------------------------------------------------------------------------------------
 IO       SYS      32576         2 RHS--A-- 1997-04-07 01:31:00 0000-00-00 00:00:00.00 0000-00-00
 MSDOS    SYS      29248        34 RHS--A-- 1988-03-14 03:21:00 0000-00-00 00:00:00.00 0000-00-00
 COMMAND  COM      24931        63 -----A-- 1991-09-11 02:00:00 0000-00-00 00:00:00.00 0000-00-00
 KDX      SYS      65536       439 RHS--A-- 1997-04-07 01:34:00 0000-00-00 00:00:00.00 0000-00-00
 KDX4SysR OM           0         0 ---V---- 1997-04-07 01:34:00 0000-00-00 00:00:00.00 0000-00-00
 AUTOEXEC BAT        189        88 -----A-- 1997-04-07 01:34:00 1996-11-20 12:15:44.47 1996-11-20
 CONFIG   SYS         80        89 -----A-- 1997-04-07 01:34:00 0000-00-00 00:00:00.00 1996-11-20
 CHKTP    COM         58        90 -----A-- 1995-12-19 01:00:00 0000-00-00 00:00:00.00 0000-00-00
 CHMSW    EXE       9536        91 -----A-- 1995-12-11 01:45:00 0000-00-00 00:00:00.00 0000-00-00
 DATETIME EXE      12282       101 -----A-- 1992-12-08 01:20:00 0000-00-00 00:00:00.00 0000-00-00
 FDFMT    EXE      14125       113 -----A-- 1994-10-24 01:02:50 0000-00-00 00:00:00.00 0000-00-00
 FMCOPYA  EXE      36102       127 -----A-- 1996-08-08 04:30:00 0000-00-00 00:00:00.00 0000-00-00
 FORMAT   EXE      16318       162 -----A-- 1993-09-07 02:10:50 0000-00-00 00:00:00.00 0000-00-00
 HFORMAT  EXE      25506       178 -----A-- 1994-06-21 02:15:50 0000-00-00 00:00:00.00 0000-00-00
 KBEMU2   EXE      16371       203 -----A-- 1995-12-08 03:00:00 0000-00-00 00:00:00.00 0000-00-00
 KMENU    EXE      40952       219 -----A-- 1993-02-17 01:59:58 0000-00-00 00:00:00.00 0000-00-00

 LBA:11                 block: 11

 KMENU    KMN       1119       259 -----A-- 1995-12-14 01:00:00 0000-00-00 00:00:00.00 0000-00-00
 KXCOPY   EXE      20230       261 -----A-- 1995-04-03 01:30:24 0000-00-00 00:00:00.00 0000-00-00
 PCFMT    EXE      14299       281 -----A-- 1995-12-22 01:00:00 0000-00-00 00:00:00.00 0000-00-00
 PCFORMAT BAT        377       295 -----A-- 1995-12-21 01:00:00 0000-00-00 00:00:00.00 0000-00-00
 RSLINK   EXE      24774       296 -----A-- 1996-08-08 02:31:00 0000-00-00 00:00:00.00 0000-00-00
 SIO2DRV  COM       3451       321 -----A-- 1995-08-31 02:00:00 0000-00-00 00:00:00.00 0000-00-00
 SPEED    EXE       7976       325 -----A-- 1993-02-23 01:40:00 0000-00-00 00:00:00.00 0000-00-00
 SYMDEB   EXE      26533       333 -----A-- 1985-10-16 04:00:00 0000-00-00 00:00:00.00 0000-00-00
 TPCAL    EXE      37510       359 -----A-- 1995-12-13 01:11:00 0000-00-00 00:00:00.00 0000-00-00
 TPMOUSE  EXE      10901       396 -----A-- 1995-12-01 03:00:00 0000-00-00 00:00:00.00 0000-00-00
 TPSYS    EXE      10300       407 -----A-- 1995-12-18 02:01:00 0000-00-00 00:00:00.00 0000-00-00
 ASING    EXE       5040       418 RH---A-- 1993-03-08 01:01:00 0000-00-00 00:00:00.00 0000-00-00
 ÕSING    EXE       5040       401 -------- 1993-03-08 01:01:00 0000-00-00 00:00:00.00 0000-00-00
 ÕP       300>         0         0 ----D--- 1995-07-31 19:10:18 0000-00-00 00:00:00.00 0000-00-00
                       0         0 -------- 0000-00-00 00:00:00 0000-00-00 00:00:00.00 0000-00-00
                       0         0 -------- 0000-00-00 00:00:00 0000-00-00 00:00:00.00 0000-00-00
« Last Edit: December 16, 2024, 07:31:18 am by fzabkar »
 
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Offline fzabkar

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Re: What more i can do?
« Reply #458 on: December 16, 2024, 07:16:11 am »
Arrggh! A Moonie!

Code: [Select]
Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00002820  05 74 05 7C 05 00 0D 0A 33 6D 6F 64 65 20 46 44  .t.|....3mode FD
00002830  2D 42 49 4F 53 20 4B 44 58 34 2E 31 2E 33 34 20  -BIOS KDX4.1.34
00002840  66 6F 72 20 46 44 43 33 37 43 36 36 31 20 28 D3  for FDC37C661 (Ó
00002850  B0 C0 4F 46 46 29 20 62 79 20 57 41 43 4F 4D 20  °ÀOFF) by WACOM
00002860  31 39 39 37 2E 30 34 20 20 52 65 76 2E 53 75 6E  1997.04  Rev.Sun
00002870  26 4D 6F 6F 6E 0D 0A 00 00 00 00 00 00 00 00 00  &Moon...........

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)
« Last Edit: December 16, 2024, 07:46:06 am by fzabkar »
 
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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #459 on: December 16, 2024, 07:54:45 am »
Did it (EPROMS DATAs) says or shows anything regarding where the issues are?  :scared:
 

Offline amyk

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Re: What more i can do?
« Reply #460 on: December 16, 2024, 07:57:48 am »
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
 
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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #461 on: December 16, 2024, 08:00:42 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)
The Disk here, what is it trying to represent.
I mean is there anything similiar to 100 Pin IC in motherboard. I think nope.
 

Offline fzabkar

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Re: What more i can do?
« Reply #462 on: December 16, 2024, 08:37:03 am »
BIOS structure

Code: [Select]
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

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: [Select]
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
« Last Edit: December 16, 2024, 10:17:33 am by fzabkar »
 
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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #463 on: December 16, 2024, 09:57:49 am »
BIOS structure

Code: [Select]
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

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: [Select]
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

Put in non working EPROMS? High or Low?
Can you make .BIN file?
 

Offline squadchannel

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Re: What more i can do?
« Reply #464 on: December 16, 2024, 10:12:03 am »
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. :-//

 

Offline m k

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Re: What more i can do?
« Reply #465 on: December 16, 2024, 10:30:56 am »
Did it (EPROMS DATAs) says or shows anything regarding where the issues are?  :scared:

No.

Do the swap and new scoping and do them exactly like before.
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 

Offline Harry_22

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Re: What more i can do?
« Reply #466 on: December 16, 2024, 12:14:28 pm »
Great job getting real information out of those ill-fated EPROMs!
Cool!

@222Lab_Test222, and as always you will have to work with your hands.
Would you going about to perform a little of the old in-out, in-out (please see the picture).

We are looking for contacts with poor clamping.
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #467 on: December 16, 2024, 12:18:24 pm »
Great job getting real information out of those ill-fated EPROMs!
Cool!

@222Lab_Test222, and as always you will have to work with your hands.
Would you going about to perform a little of the old in-out, in-out (please see the picture).

We are looking for contacts with poor clamping.
I can try that.
Check all the poor solders and clamps?
just check with hands? Whats a little in out things, i do not understand, i saw the picture BUT still unclear.
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #468 on: December 16, 2024, 12:20:02 pm »
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. :-//

I just watch his video, well there was same CPU as we used in this motherboard, the way he program that Beep Code was insane.
 

Offline Harry_22

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Re: What more i can do?
« Reply #469 on: December 16, 2024, 01:09:54 pm »

just check with hands? Whats a little in out things, i do not understand, i saw the picture BUT still unclear.

I suppose that the reason may be in the weakened contacts of the DIP-circuit bushings under IC16.

I would advise you to take any DIP chip, bend one leg and try the clamping force of the contacts one by one.
If all the contacts are tight, spray them with contact cleaner and go around in a circle with this chip making an in-out.

It would be better to change the entire IC panel, but only do this if my guess is confirmed.
 

Offline asis

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Re: What more i can do?
« Reply #470 on: December 17, 2024, 01:49:54 am »
Hi,

@222Lab_Test222

Sorry.

I can't see the wires well on the Back PCB picture, so I thought that IC7 74ACT08 is somehow connected to the X1 crystal.
But now I realized that the schematic is as in the .pdf.
So look at pins 14 or 15 Xtal through a 1:10 divider and use a 2-Ch scope to observe DOUT / TP.
However, have you tried adjusting C10?
Have you tried manipulating the button on the PCB.
Is it Reset?
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #471 on: December 17, 2024, 03:32:20 am »
Hi,

@222Lab_Test222

Sorry.

I can't see the wires well on the Back PCB picture, so I thought that IC7 74ACT08 is somehow connected to the X1 crystal.
But now I realized that the schematic is as in the .pdf.
So look at pins 14 or 15 Xtal through a 1:10 divider and use a 2-Ch scope to observe DOUT / TP.
However, have you tried adjusting C10?
Have you tried manipulating the button on the PCB.
Is it Reset?
Yeah thats reset.
 

Offline m k

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Re: What more i can do?
« Reply #472 on: December 17, 2024, 07:07:06 am »
You've been told to be methodological, for now you're not.
Earlier data and address scopes was the only exact thing lately, use it.

If scoping swapped ROMs is too difficult you can get one of those cheap Sigrok compatible 8 bit logic analyzers.
Don't forget mini grabbers for pins if they are missing.

Using the analyzer you measure CS, OE and two of D7-5, no matter which ones, of both ROMs simultaneously, you can do this to all faulty boards.
When CS and OE goes down the data bus contains ROM data, your earlier measurement says that the data is not correct, so all other parts are irrelevant until you get that data right.

First you measure directly from ROM pins, correct data is so that one pair is up and up when other is down and down.
If that data is present you change the measurement so that you measure one nibble(4 bits) at the time.
Correct data for first nibble quartet is E 9 0 D, order can be different but content not.

Next you can obviously do many things, but be methodological.
The methodological thing is to move the next measurement to the other side of the socket contact.
If socket is a through hole the underside is an easy target, sort of.

Keep in mind that measuring from the underside of a socket doesn't mean that the chip is getting the signal.
Note also that measuring from the chip's leg and pressing the probe can lead to connection of a bad contact, this can be your earlier measurement discrepancies, but in opposite way, the measurement was faulty.
Pushing and pulling can also be pressing, direction of contact defines.
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 
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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #473 on: December 18, 2024, 02:29:36 am »
 Sorry guys,
I will be quite busy these weeks, i will be back next week.
 

Offline asis

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Re: What more i can do?
« Reply #474 on: December 18, 2024, 03:33:32 am »
Hi,

@222Lab_Test222


Could you please read the inscriptions (if any) on the uPD4990 on the working PCB(s) indicating the batch number and year of manufacture and compare them with the inscriptions on the IC23 chips on all the non-working PCBs.

I suspect that this is a "2000Year" problem.

If you are confident in yourself, you can move the chip from the working board to the non-working one (or vice versa).
 


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