This is the initial design for the prototype bezel to hold the ZJ050NA-08C
There are some challenges with 3D printing due to how thin some areas are. I expect to receive an SLA print of this on this coming monday, and from there I will look at additional revisions and print another one until it is just right.
With some surface finishing I hope we can get it close to looking factory, but certainly it will be functional from a mechanical perspective.
I decided to take some comparison shots of a working display. I also contemplate how to preserve this screen long term. Although my focus is on TFT displays for practical use, I do have interest in preseving the original screen as long as possible just for sentimental reasons.
I continue to work on various aspects of the PC110, but updating information online in of itself is a task!
Bios Patcher I continue to work towards understanding the method xpatch.exe uses for updating the flash memory, with the goal of creating a “vpatch” which will make the required modifications to the CT65535 bios for use with the TFT display. I will not get too adventurous until my ZIF sockets arrived so I can easily repair the flash program in the event an early version of vpatch “bricks” the unit.
I am using a combination of Turbo Debugger and Ida to understand and follow the actions. I was unable to find documentation for the VLSI VL82C420FC5, however I did find one for the VL82C480, and it appears that many of the configuration registers must have been shared between them.
I have put the AT050TN22 V.1 on the shelf for now, it seems to be very sensitive and not electrically compatible with the PC110 without some further electronics, perhaps some kind of impedance matching, this is something I do not know enough about right now to deal with properly.
The ZJ050NA-08C however works almost perfectly without any special conditioning of the signal lines. I had a slight issue with blue, it may have been a solder bridge or an error in my PCB, I will address this in the next revision of the board. There are some mechanical changes now needed as the ribbon cable location is changed, and the analog power and backlight requirements are different.
This was the concept V2 PCB but it will be totally different for the new display. Of course I had mixed up the footprint of the 30pin connector which is why it does not go in the correct direction.
Bezel I spent some time in Fusion 360 drawing the bezel, however I just do not have the time to do this properly so I am going to go back to my original plan and find somebody local to draw it for me.
I got quotes for injection molding tooling, and it would be around $3000. If 3D printing cannot produce a good enough result, this may be the only way to get a professional result. I would need to sell additional pieces over time to recover that cost. Maybe $50 dollars each or something.
Keyboard/Mouse Dongle I managed to find the propritary keyboard/mouse dongle online so I will be able to look closer at the possibility of 3d printing a custom 1mm pitch housing and using other JST or other style pins to fit into it.
Despite making a template to ensure fitment I made a mistake with orientation/footprint of the 30pin connector, and it is already in production so it is too late to change. It should be fine for testing, I will have to mount the connector backwards.
I have done this previously, but this another run with the AT050TN22v1 and its matching VGA driver connected to the external VGA of the PC110 docking connector. Display is slightly cut off because the screen is just in there temporarily. This just to remind myself and demonstrate again that the screen is in fact okay and has good contrast and can properly display all the colours.
These are just captures from the external VGA port of the modetest outputs, it is useful as quick reference when looking at the outputs when generated on the LCD without switching back and forth while changing XR values.
I had attempted previously to try and identify the values for each pin manually with a logic analyzer and colour bands same as Mr.Taka has attempted previously, but as we both suspect this leaves room for error. Additionally the assignments can change based on XR values for colour width and other settings so this makes documenting even harder when it is not certain which mode is active sometimes.
I tried another approach which maybe was already tried. I attempted to work backwards from the OEM display Citizen pin-out comparing the recommended connections with C&T for similar screens and take those as the assumed pins and then move forward to the TFT15 values.
On PCB V1 only line line for sure was bad. I noticed that usually RED was showing as Yellow, and Red+Green=Yellow, so I realized that one of the RED pins on PC110 has to be connecting to Green pin on VGA. Identified it as PC110#21 to VGA#25 (G2). I cut the trace on the PCB and I now had no cross mixing of colours, but they were still very wrong, likely because if misorder MSB to LSB as well as missing lines.
My approach purely from documentation and not practical testing leads me to believe that PC110#21 is RED2, which is consistent with the issue I was having.
The only immediate issue was that I forgot to connect VCOM pin 46, so I had to put a jumper on. Pin6 VCOM was okay. Based on previous issues I believe each one supports alternating lines.
As expected there are some issues with the colour, it seems that it may be specific to red but requires some more investigation. I consider the test successful though in that I did not see any “noise”, the picture was perfectly stable with no flicker.
The physical fitment was also good, however I wrecked my last 30pin connector so I had to use one salvaged from the old CSTN which is why I have the screen positioned strangley.
I got the correct adapter in and I have successfully dumped the contents of the flash. As expected the video bios is there. I am certain I could modify the XR registers in the vbios binary just like C&T BMP and it would work. The challenge now is how to flash from software.
Analyzing the contents of the flash should help me confirm I am reading it correctly through the flash chips CUI (Command User Interface), which is something I am still working on, based on the dissassembly of xpatch.exe
I did not get the [email protected] from this yet, it had a sticker that said REV0.33
To make the TFT conversion complete, we need to modify the ROM bios to have the correct configuration values for the new display.
After some research I learned of the BMP (Bios Modification Program) provided to OEM’s by Chips&Technology for customizing the CT65535 video bios. It is simply a program that allows you to customize the bios binary. I was not able to find the BMP file for a CT65535 only a CT65545, however it was easy to see what it was doing and confirm that I had located the correct bytes within the video bios I had dumped from C000h.
I am expecting to find a copy of this video rom on the intel flash chip. I do not have the correct TSOP-40 for my ChipProg-40, however I will receive it next week and will dump the contents of the flash to confirm its contents and locations.
For my purposes I am fairly confident I will be able to edit the values, reprogram and put the chip back on. This is not ideal though so the goal is to flash/patch it with a program. I have been reviewing the xpatch.exe to understand how this is possible. I will not attempt anything until I have verified I can backup and program the chips off the board.
This is a disassembled version generated by Sourcer. This is VERY preliminary. I am also investigating with IDAPro 5.0 Free, which properly opens a MZ executable.