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Reply 540 of 554, by Oerg866

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Hello, it's me again.

Has anyone had issues with the PS/2 mouse (with this modification) not working in Windows 98 but working without issues in DOS?

Reply 541 of 554, by feipoa

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Oerg866 wrote on 2024-04-08, 10:58:

Hello, it's me again.

Has anyone had issues with the PS/2 mouse (with this modification) not working in Windows 98 but working without issues in DOS?

I don't think I have tested the PS/2 mouse mod in Win98, but every system I've used it in which contained Windows 95 has run beautifully. Normally I have to set the PS/2 rate to 80 Hz though, as the default for W95 (40 Hz, I think) isn't as smooth as I'd like it.

Plan your life wisely, you'll be dead before you know it.

Reply 542 of 554, by Paar

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Tried to mod AOpen VI15G for PS2 mouse support. All unpopulated pads were there but after soldering everything, the boards locks up after couple of seconds after boot. Had to move some ferrite beads and resistors around. Even tried to swap the KBC but that didn't help. I wonder what I'm missing. Interestingly, when I turn the "Enable PS2 mouse" option in the BIOS to "false", the keyboard works fine, meaning the controller is properly set in PS2 mode and not in AT mode (as the connections for AT mode are severed after the mod).
Checked everything with my multimeter and all connections seem fine. Maybe some IRQ conflict but I don't have any peripheral installed apart from graphics card.
Has anyone here been successful with modding this board?

The attachment vi15g_1.jpg is no longer available
The attachment vi15g_2.jpg is no longer available

Reply 543 of 554, by maxtherabbit

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feipoa wrote on 2024-04-10, 02:49:
Oerg866 wrote on 2024-04-08, 10:58:

Hello, it's me again.

Has anyone had issues with the PS/2 mouse (with this modification) not working in Windows 98 but working without issues in DOS?

I don't think I have tested the PS/2 mouse mod in Win98, but every system I've used it in which contained Windows 95 has run beautifully. Normally I have to set the PS/2 rate to 80 Hz though, as the default for W95 (40 Hz, I think) isn't as smooth as I'd like it.

I've run 98 on a modded board, works fine

Reply 544 of 554, by NightmareJoker2

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maxtherabbit wrote on 2023-05-12, 17:34:
Paar wrote on 2022-03-28, 17:01:

In that case it could be better to place all the components on the bottom of the board to get another mm or so. Will probably need to modify it to be usable with my board. The prospect of getting native PS2 support with 486 is a strong one.

I just did a version like that. Passes DRC but hasn't been prototyped yet, so caveat emptor

The attachment ps2 interposer v3.zip is no longer available

I have downloaded these gerbers and had a look. It looks like the PS/2 port is not the same as what the PS/2 slot brackets use that you can still buy here or here
Do you think it's possible to make a version that uses the normal IDC 2x5 pinout?
s-l1600.jpg
Not visible in this picture from the eBay listing, pin 2 on the IDC connector is blocked (no pin).

Also, it's not entirely obvious which type of inductors need to be used. What current rating would be required? Is it okay to just use NL453232T-471Ks?
Could I have the KiCad project files so I can make the edits myself?
Since I'd have to order more boards or parts than I need to make myself an adapter or two (usually enough to make 10 or 20), would it be okay to sell the excess at cost to people who want an adapter but would be fazed by the prospect of making it themselves, or do you have objections to that as the copyright holder of your PCB design?
Continuing the thought, there is a solder bridge on the bottom of the board to connect pin 5 of the motherboard socket to pin 5 of the adapter socket, in case the pin is already connected to IRQ 12 on the motherboard. Would it be possible to break out this pin 5 from the motherboard socket to a pin adjacent to the IRQ12 pin on the adapter that is next to the PS/2 port IDC connector, such that installing a jumper instead of a wire that goes to an ISA socket in such a case could be done instead?

Reply 545 of 554, by froller

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Paar wrote on 2024-04-25, 16:14:

Checked everything with my multimeter and all connections seem fine. Maybe some IRQ conflict but I don't have any peripheral installed apart from graphics card.
Has anyone here been successful with modding this board?

System works until you touch the mouse isn't it? If so it's certainly an IRQ issue.
1. Check that IRQ12 is not in use by any devices except KBC.
2. Take a closer look at JP16 and JP17. I bet one of them is connected to Pin36 of KBC and responsible for IRQ12 routing. Other one is probably for Color/Mono switching.
The one that leads to Pin36 must be closed for PS/2 mouse to work properly.

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Reply 546 of 554, by Paar

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froller wrote on 2024-09-30, 21:04:
System works until you touch the mouse isn't it? If so it's certainly an IRQ issue. 1. Check that IRQ12 is not in use by any dev […]
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System works until you touch the mouse isn't it? If so it's certainly an IRQ issue.
1. Check that IRQ12 is not in use by any devices except KBC.
2. Take a closer look at JP16 and JP17. I bet one of them is connected to Pin36 of KBC and responsible for IRQ12 routing. Other one is probably for Color/Mono switching.
The one that leads to Pin36 must be closed for PS/2 mouse to work properly.

Thanks for a tip. JP16 is used for CPU configuration, I have no idea (yet) what it does exactly. JP17 is either unconnected or connected in inside layer without direct trace visibility. I don't know where it goes, definitely not to a KBC, chipset or CPU socket. Actually it's JP14 (between third and fourth ISA slot) which I had to add that connects to IRQ12. What could cause a conflict on IRQ12 when nothing but a keyboard is connected?

Reply 547 of 554, by NightmareJoker2

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Paar wrote on 2024-10-17, 18:10:

What could cause a conflict on IRQ12 when nothing but a keyboard is connected?

It is impossible to have nothing but a keyboard connected. The system will not POST without a graphics adapter, and not boot past an onboard ROM (i.e. BIOS, ROM BASIC) without a storage or network controller present.
Just because something isn't on an expansion card, doesn't mean it's not connected.
IRQ 12 can be used by any device on an expansion card or on the motherboard, if it has any integrated into it.
Before PS/2 mice came along, IRQ 12 was considered free for expansion cards like HDD and SCSI controllers, network cards, CD-ROM controllers, modems, and the like to use. Now they're mostly fighting over 5, 10, 11, and maybe 15: https://en.wikipedia.org/wiki/Interrupt_request#Master_PIC

Reply 548 of 554, by Paar

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This board doesn't have integrated I/O and I haven't connected any such card when testing. So at least this is out of question. I have recently obtained an oscillator from China, so I'll do some measurements. Hopefully I'll figure it out, VI15G is such a nice board, just native PS2 mouse connector is missing for it to be near perfect.

Reply 549 of 554, by froller

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Paar wrote on 2024-10-17, 18:10:

Thanks for a tip. JP16 is used for CPU configuration, I have no idea (yet) what it does exactly. JP17 is either unconnected or connected in inside layer without direct trace visibility. I don't know where it goes, definitely not to a KBC, chipset or CPU socket. Actually it's JP14 (between third and fourth ISA slot) which I had to add that connects to IRQ12. What could cause a conflict on IRQ12 when nothing but a keyboard is connected?

Technically it's not a conflict. It's unhandled interrupt.
When you move your mouse KBC fills its internal buffer with mouse data and triggers the IRQ12 line to tell the CPU to read the buffer. KBC is stuck while the buffer is full.
If you break IRQ12 line (leave JP14 open) the CPU never gonna know if it is requested to read the mouse data from KBC. And there you got the deadlock.

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Reply 550 of 554, by Paar

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My problem is the computer gets stuck even with the line connected. It goes from KBC to ISA pin with IRQ12 and to a pin on the chipset. Couldn't find anything else connected to it. I will retest it and check the state of IRQ12 with oscilloscope if it isn't stuck or something.

Reply 551 of 554, by froller

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Paar wrote on 2024-10-19, 10:26:

My problem is the computer gets stuck even with the line connected. It goes from KBC to ISA pin with IRQ12 and to a pin on the chipset. Couldn't find anything else connected to it. I will retest it and check the state of IRQ12 with oscilloscope if it isn't stuck or something.

Do you have PS/2 mouse handling enabled in BIOS?
No matter at all if it is broken IRQ12 line or no poroper IRQ12 handler installed. KBC will remain stuck until buffer is read.

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Reply 552 of 554, by Paar

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Yeah, I have it enabled. The computer doesn't hang when I disable it, even though the jumper is connected. The keyboard works fine in such scenario, meaning the KBC is properly set into PS2 mode.

Reply 553 of 554, by froller

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Paar wrote on 2024-10-19, 17:40:

Yeah, I have it enabled. The computer doesn't hang when I disable it, even though the jumper is connected. The keyboard works fine in such scenario, meaning the KBC is properly set into PS2 mode.

Keyboard schematics and protocol for AT and PS/2 are identical. So keyboard should work anyway.

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Reply 554 of 554, by Paar

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Yeah but the pinout on the KBC is different based on the default mode of the motherboard. The board is wired in AT mode originally, I had to move some resistors and inductors around to make it wired in PS2 mode. I probably overlooked something but at least I'm sure the wiring from KBC to keyboard/mouse connectors is okay, double checked that.