USB vs Ps2 Keyboards

[ricercar]

PS/2 fits in a crayon sharpener. Try that with USB!

[keyb_gr]

To be honest I have not used my serial and parallel ports in ages, but they do tend to be very handy for special applications, like reviving semi-dead harddrives that have hung up due to a firmware bug, or controlling some ICs with an I2S interface (it takes a "real" parallel port for the latter though, a USB adapter won't cut it - by contrast, there are a few USB RS-232 adapters suitable for low-level stuff around).

Incidentally, even my trusty P2B-D (10 year old technology) has USB legacy support and I can use a USB keyboard for the BIOS setup just fine. Gotta try on the truly historic GA-686KDX.

[microsoft windows]

Even my oldest computer (Asus A8N SLI Deluxe) allows me to access everything through USB at bootup.  In fact it's useful because I use a DiNovo Mini Bluetooth to access the media computer in a wiring closet downstairs from the TV room.  Try doing that with PS/2!

Your oldest computer is not old. Even my NEWEST machine doesn't do that!

[HaaTa]

Well, I bought a Gigabyte EP35 (DS3P I think) a while a back, it actually has headers on the motherboard for serial and parallel ports. Mind you its more than a year old now.

[Rajagra]

Even my oldest computer (Asus A8N SLI Deluxe) allows me to access everything through USB at bootup.

Really? Can you hit print screen from inside the BIOS to get a screendump like you can with parallel printers?

[ricercar]

My Commodore SX64 has no USB, no PS/2, but it does have mechanical key switches.

[keyb_gr]

Really? Can you hit print screen from inside the BIOS to get a screendump like you can with parallel printers?

That most probably not. I think the HID protocol was the only one deliberately kept simple so that key codes could be extracted just by looking at the packets.

[grantb3]

With USB, you get no "press F12 for boot menu" time.

I do.

[nowsharing]

Are there power usage benefits to using an active usb converter? I read this at clickykeyboards.com:

Quote:
Online reports indicate that vintage IBM ps/2 keyboards pull up to 100x more current compared to modern keyboards (112 mA vs 1.2 mA). see reference: (http://www.geocities.com/jszybowski/keyboard/index.htm). One way to resolve this problem to add resistors to change the voltage, or an easier non-destructive fix is to use an active ps/2 to USB plug-in converter with built-in electronics.

This sounds like it might add a longer life to older Ms?

Sorry to dig up this old thread. My blue cube came in today and it reminded me of a question I asked in this thread: Does converting to USB make our old Ms draw less current, perhaps extending the life of the onboard electronics?

[Rajagra]

Now the M2 - those have like a 50% failure rate.

Sounds right. 50% of the 2 electrolytic capacitors in mine had failed, making it unusable. :rofl:

Fine since the repair though.

[keyb_gr]

Does converting to USB make our old Ms draw less current, perhaps extending the life of the onboard electronics?

Of course not. That text you quoted wasn't worded overly well. It's not like the adapter would magically decrease the power consumption, but rather the higher current available with USB power compared to problematic PS/2 ports makes things more likely to work. It should be a +5V supply in either case.

[ch_123]

The keyboard is going to consume as much power as it needs regardless. The issue here is that there are some motherboards whose PS/2 ports are inferior to the likes of the Blue Cube or the Belkin, so they actually are more reliable when used with the latter.

[kishy]

Since current was brought up, I should mention this (I will edit this post very soon after making it, because I need to get to one of the links in my sig to find what I'm looking for)

Edit: had to go through 14 pages to find it, but I found it.

http://geekhack.org/showpost.php?p=123069&postcount=186

1986 terminal keyboard was identified as using nearly 200mA of juice. I thought I had included a test with a normal Model M at the same time; apparently not. Presumably the controller PCBs don't differ too much though.

[Manyak]

The keyboard is going to consume as much power as it needs regardless. The issue here is that there are some motherboards whose PS/2 ports are inferior to the likes of the Blue Cube or the Belkin, so they actually are more reliable when used with the latter.

It's not the adapter that allows more power, it's the USB ports of the PC you're connecting it to.

[Nonmouse]

What's a parallel port???  :biggrin1:

You can't be serial....

[Nonmouse]

Yes I am.  USB is infinitely more powerful than PS/2.

Try boiling water with a PS/2 port.

I think I DIN hear you correctly....

[ch_123]

It's not the adapter that allows more power, it's the USB ports of the PC you're connecting it to.

Never said otherwise. In theory, PS/2 offers more power, but in reality, a lot of motherboards skimp on it.

[kishy]

Never said otherwise. In theory, PS/2 offers more power, but in reality, a lot of motherboards skimp on it.

Sorry but what's the theory behind that? Spec called for a max of 200 or 250 mA, I can't recall which.

USB spec requires a minimum supply to keep a device drawing up to 500mA happy at all times.