I've been chasing a junk board for a long time, but I'm stuck, so I left it.
After that, I was looking for a "able power on, but immovable junk PC110", but I finally found it, so I bought it at a reasonable price, including moving parts and peripheral devices.
This immovable junk is named Unit No.8 "Ume / Plum", and I'll check the condition, and if possible, I want to make it a "working item" at the end. (Equivalent to \ 3,000)
With "PC110", the reason that the power is turned on but the operation does not proceed is that there is a slight misjudgment in the early part of BIOS, or I'm wondering if it's being stalled because of some small hardware failure.
． ． ． What happens if I skip it?
I'm wondering if I could get out of the immobile state by replacing it with a "proper BIOS".
But I'm still not sure. So I would like to investigate more various cases.
This time, Unit 8 "Ume / Plum" seems to proceed to a considerable stage from power-on. (Fig_1)
When I are lucky, I can also see the display of "memory size" or the blinking LCD screen. (Movie 1: <click> or "YouTube"）
I think this is a proof that the "timer" is working properly, but I still don't know the reason why it stops from here.
By the way, while looking down the open area of the connections of "LCD cable" or "Inverter lead wire", "repair of blown fuse" may go well I think, and I done it.
I'll summarize about it in the next article.
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+++ Memory size display +++
(The cause is not clear,) In some cases, "Memory size" appears on the external display.
(If the liquid crystal is healthy, it will also appear on the LCD screen.)
After that, the "cursor blinks" only and the process stops, but this memory size corresponds to the actual amount of "extended memory" installed, which is interesting ! (Fig_3)
Initially, I was skeptical, but when I replace "Extended memory" (Fig_4 <click>), the value corresponding to it is displayed, so I found that the BIOS is working to that point...
But He don't know about "clock display" !?
As for this machine, I removed the "Gourd Battery" at the same time as I got it and cleaned the area with a toothbrush. Also, the yellow jumper wire was firmly attached, and the "expansion connector part" still seems healthy ! (Fig_4 <click>)
+++ Dream of modifying the BIOS part +++
Mr.Moonlight has been trying the creation of "VPATCH" for making the TFTized screen.
This is related to the rewriting of the display-related parts, and I think that it will require considerable changes.
So I think it's a very heavy task, including debugging, but I have high expectations for him.
Little by little, I'm working through the early routines of the BIOS to find out what and in what order. (Fig_5)
However, unfortunately, it has not progressed slowly. (Fig_6 <click>)
... The main purpose is to repair by myself, and there are some aggressive measures such as "remove the normal BIOS chip and replace it with it" as the last resort of BIOS repair.
However, this is the same as "living organ transplantation" that seems to be actually performed in the some place, and it is horrible and meaningless, so I do not want to do such work.
It's the best way, if I could make a "normal copy chip" without removing the chip from the main body, but it is almost impossible now.
With very slowly way, but I would like to continue searching for "appropriate donors" or proceed with "iPS cell method".
