Suggestion Request - USB to PS2

[rfdes]

I am ramping up to do some legacy software/hardware development on a legacy (1996) PC running.  The PC does not support USB and I desire to set up a KM (no video) switch so as to use my current keyboard/mouse.  The legacy computer only has PS2 inputs and wanted to use a USB to PS2 adapter as the interface.  However, I see plenty of female PS2 to USB adapters but no USB to male PS2 adapters.  If they exist I am struggling to find one.  Also, I was wanting to know if there is a no-frill USB redirection application for performing the switch between my Win11 to Win2K.  Does anyone have a minimal hardware/software approach to doing this? The diagram below is what I'm looking for.
Thanks

[coromonadalix]

you do have ps2 male to usb female   but the hardware put on them need to be compatible

and maybe on vogon web site,   there is some card interface or maybe some github projects  who could do the job  ...


you're dealing with 2 different technologies and switch between them as you know can be done to some extent,  you have some pci card who can add usb 2.0  interfaces, even some oldies ISA card slots who can add usb 1.0  support ...   

and keeping an legacy system and doing dev on it is not good,  unless you use some legacy who as a very long term support ?

why don't you use virtual desktop / machines inside windows 10 or 11 ?   

what's this legacy can do  vs a more recent era machine can't ?


isa to usb   https://www.ebay.com/shop/isa-card-usb?_nkw=isa+card+usb   
but have only one port,  not sure if you can add a hub on them

plenty of pci 32 bits to usb 4 and 5  ports     on ebay or elsewhere ?

unless i absolutely dont catch your needs ?

[pcprogrammer]

A quick google search gave me this:



Did not watch the video but the github page mentioned in the description shows what looks like what you want. https://github.com/rasteri/HIDman

[wraper]

Using PC as a pass through USB sink device is like to eat with your butt and to shit through the mouth. While theoretically it's possible, I do not recommend it   . Not to say you need to convert it into PS/2 protocol anyway with some active interface converter. On other hand some low end USB keyboards and mice (specialized chip, not MCU based), especially older ones, may support PS/2 natively with passive connector adapter.

[rfdes]

Thanks for the visual that's some helpful advice! 

Just looking for a simple way to communicate with this old PS2 PC without using a separate keyboard (desk space is scarce).  Also, trying to avoid the KVM box approach (I don't need video).   I was hoping a simple adapter approach would be possible with little hassle.

[pcprogrammer]

Just looking for a simple way to communicate with this old PS2 PC without using a separate keyboard (desk space is scarce).  Also, trying to avoid the KVM box approach (I don't need video).   I was hoping a simple adapter approach would be possible with little hassle.

Which you would have found if you looked at what I posted. It seems you can buy something here: https://retrohackshack.com/product/hidman-usb-keyboard-converter/

[rfdes]

Yes, you're correct.  That looks promising.  Thanks for the link.
Take care.

[android]

Do you mean something like this? I have about 70 of them that I rescued from a skip 25 years ago  (not a hoarder).
They were made by Microsoft. I cracked one open and there are no chips - just a couple of 4k7 pullups (or downs) - hinting that (for mice at least) USB is straight through compatible with PS2.

[wraper]

I cracked one open and there are no chips - just a couple of 4k7 pullups (or downs) - hinting that (for mice at least) USB is straight through compatible with PS2.

USB is not compatible at all. Mice and keyboards may have both interfaces implemented. In the past, before fancy MCU based mice and keyboards appeared, nearly all of them had PS/2 implemented along with USB as it was implemented in most of specialized ICs they were based on.

[jpanhalt]

Here's another option: https://www.versalent.biz/

The owner, John Ursoleo, has been very helpful.  I learned about that device from Fraser's post about 10 years ago.  It converts USB to RS232 for keypads and number pads.  It's a niche product, and from my communications with him, he used to sell a USB to PS2 product, but because of the very low demand, he discontinued it.  You would need to convert the RS232 to PS2.  Any small MCU should be able to do that.  A PIC16F1xxx might be a simple way to start.  That's what I am using for a different project.

I got my device from him directly a few weeks ago, and it works.

[coromonadalix]

Do you mean something like this? I have about 70 of them that I rescued from a skip 25 years ago  (not a hoarder).
They were made by Microsoft. I cracked one open and there are no chips - just a couple of 4k7 pullups (or downs) - hinting that (for mice at least) USB is straight through compatible with PS2.

yep as @wraper wrote   they  could support both usb and ps2 protocols,  this plug was passive  you had the green and violet ones,  green for mouses and violet for keyboards  loll   but i think they had the same connections inside them

[jpanhalt]

The legacy PC the TS is using does not support USB.  Can you explain how a straight-through  (e.g., plug adapter) will work with a USB device and no host?

[pcprogrammer]

The legacy PC the TS is using does not support USB.  Can you explain how a straight-through  (e.g., plug adapter) will work with a USB device and no host?

Back in the early days these USB mice and keyboards had special interfaces that detected if it was connected to either USB (2 wires*) or PS/2 (also 2 wires*) and switched to the appropriate interface. So no USB when connected to a PS/2 port, but plain old PS/2.

* except for the power wires that is.

[jpanhalt]

Thank you.  I didn't know that and am quite new to playing with USB.  However, will the more modern USB the TS wants to use support that type of link to a PC without USB?

[HwAoRrDk]

isa to usb   https://www.ebay.com/shop/isa-card-usb?_nkw=isa+card+usb   
but have only one port,  not sure if you can add a hub on them

Note that those CH375-based ISA cards are only intended for use with USB flash storage drives. The available drivers for them (at least, for DOS - I don't know about Windows) don't support connecting any other kind of USB device (keyboard, mouse, printer, etc.).

[amyk]

I believe the most significant reason why converters from USB device to PS/2 host are far more common is that a USB port allows up to 500mA while a PS/2 port allows, depending on the sources I found, anywhere from 100mA to 275mA max.

[BradC]

Here is an expensive one : https://www.kvm.com.au/Product-adder-usb-ps2-converter-cable-adapts-usb-kbms-ps2-style-inputs-for-use-with-older-pc-576.aspx

I have several cheap ones. They used to be plentiful, but I don't see much on offer these days.

[NiHaoMike]

Just get a PCI USB card for the old PC? It won't work in the BIOS but will work once booted into the OS.

[pcprogrammer]

Thank you.  I didn't know that and am quite new to playing with USB.  However, will the more modern USB the TS wants to use support that type of link to a PC without USB?

Probably not, because I doubt that the KM switch the original poster is talking about will support this. Also when a wireless keyboard / mouse combination is used with only a single USB dongle, it won't work because PS/2 only supports a single dedicated device on it's ports. Keyboard on the keyboard port and mouse on the mouse port.