USB vs. PS/2


D

Dishum

I've heard of people having problems with a USB keyboard because
it's doesn't work until the OS has loaded the driver, being
unable to go into BIOS or use the boot option hotkey, or press F1
when a fault occurs in POST. It just occurred to me that I've
never used a USB keyboard and I don't have one with me to try
out.

A quick search seems to indicate that the problem occurs with
some motherboards but not with others. I've also observed mice
behave smoothly into a PS/2 port and erratically with USB. The
trend is apparently towards USB for both keyboards and mice and
many new mobos come with only one PS/2 port. I even saw someone
in a forum declare that "PS/2 needs to die".

Can anyone please clarify the situation and explain why PS/2 is
falling out of favour?
 
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P

philo

I've heard of people having problems with a USB keyboard because
it's doesn't work until the OS has loaded the driver, being
unable to go into BIOS or use the boot option hotkey, or press F1
when a fault occurs in POST. It just occurred to me that I've
never used a USB keyboard and I don't have one with me to try
out.

A quick search seems to indicate that the problem occurs with
some motherboards but not with others. I've also observed mice
behave smoothly into a PS/2 port and erratically with USB. The
trend is apparently towards USB for both keyboards and mice and
many new mobos come with only one PS/2 port. I even saw someone
in a forum declare that "PS/2 needs to die".

Can anyone please clarify the situation and explain why PS/2 is
falling out of favour?



Never saw the sense of USB keyboards or mice

The only time I use them is if there are no ps/2 ports on the machine...
or possibly to save a machine with a broken ps/2 port
 
B

Bert

In "Dishum"
Can anyone please clarify the situation and explain why PS/2 is
falling out of favour?

My USB keyboard works fine at boot time on my very, very old Asus P4PE
motherboard. But as they say, YMMV.

Makers probably just want to eliminate as much hardware as they can from
their products.
 
D

Dishum

philo said:
Never saw the sense of USB keyboards or mice

The only time I use them is if there are no ps/2 ports on the
machine... or possibly to save a machine with a broken ps/2
port

Same here. When I said that I've never used a USB keyboard, I
meant for regular use. I use USB keyboards and mice for exactly
the same reasons as yours and such times are only when I work on
and with other people's computers.
 
R

Rick Massey

Dishum said:
I've heard of people having problems with a USB keyboard because it's
doesn't work until the OS has loaded the driver, being unable to go into
BIOS or use the boot option hotkey, or press F1 when a fault occurs in
POST. It just occurred to me that I've never used a USB keyboard and I
don't have one with me to try out.

A quick search seems to indicate that the problem occurs with some
motherboards but not with others. I've also observed mice behave smoothly
into a PS/2 port and erratically with USB. The trend is apparently towards
USB for both keyboards and mice and many new mobos come with only one PS/2
port. I even saw someone in a forum declare that "PS/2 needs to die".

Can anyone please clarify the situation and explain why PS/2 is falling
out of favour?

I made the transition to USB for the connections somewhat under duress, as
my old KVM switch was always unreliable. (It uses a physical switch to
change things.) Also I got a new Dell desktop that had no PS2 ports, so to
do anything on that machine I had to do it all with USB I/O. The Trendnet
KVM I bought made me long for the days of PS2 ports.
That said, there are some advantages. For one thing you only have to make
one connection to the USB port from the KVM, as multiple devices can exist
on one USB port. (I have this going in, too, as my keyboard has two USB
ports on its backside) There's also never any problem of connecting the
wrong device to a port. But I don't think the easier wiring is really that
big of a deal.
I haven't had any reliability problems with the USB devices -- this Gigabyte
motherboard recognizes them in the BIOS, so there's no difficulty there. And
when I manage to get a new KVM switch installed I'll then be able to better
comment on reliability.
 
P

Paul

Dishum said:
Same here. When I said that I've never used a USB keyboard, I
meant for regular use. I use USB keyboards and mice for exactly
the same reasons as yours and such times are only when I work on
and with other people's computers.

PS/2 for that purpose, is a superior solution, for the
reasons mentioned. The OS always seems to recognize it (unless
the PS/2 port is blown out, by hot-plugging it, and you don't
get too many reports of that type). It just seems to work. And
because it's interrupt driven, the response is instantaneous. With
USB, the USB bus uses a polling method, to determine if devices have
info to offer, and if the polling process is delayed for any reason,
then so is your input delayed. Perhaps the addition of a new USB device
(just plugged in), can affect the keyboard/mouse USB response slightly.

The reason Intel is on such a mission, to remove PS/2, is so the
SuperI/O chip can be completely removed from motherboard designs.
At the moment, perhaps the hardware monitor function is all that
remains of it (once floppy, parallel port, serial ports, CIR/SIR,
PS/2 are removed). The only bit Intel is missing, is ADC converters
capable of measuring power supply voltages (which as of today,
would still be an accessory function available on about half the
SuperI/O chips). And perhaps Intel doesn't think that function is
worth having, or perhaps Intel doesn't even recognize that as an
"official" chipset function as such.

Once the legacy interfaces are removed, and all the third-party
chipsets are removed from competing with Intel (by lacking a
license for the bus interface), then Intel provides all the
"intelligent" functions. The only things left on the motherboard
are peripheral chips (NIC, HDAudio chip, Firewire chip), or
regulator chips (VCore, VDimm regulators). It would mean, for
each motherboard sold, Intel makes the maximum profit from it.

With the recent removal of PCI bus from the motherboard, for
a few years there will be motherboards with a PCI Express to PCI
bridge. But eventually that will disappear from all boards as well.
I think Z77 may be the beginning of chipsets for desktop, without
a PCI bus being available natively. The interface solutions then
are PCI Express and USB2/3, for virtually everything. Which means
every time you need a legacy solution (such as when I needed a
serial port for a dialup modem), it's a trip to the computer store
and forking out $29.95. Same thing happened when I needed a parallel
port to run a hardware programming dongle - another trip to the
store, and fork out more money, for a PCI Express to parallel port card.
Interfaces are *so* much cheaper, when they're bundled with the motherboard.

Paul
 
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P

philo

I still prefer old school PS/2 ports, but they getting more rare with
newer motherboards these days. I tried to get this EVGA X58 SLI
(132-BL-E758; BIOS date 5/11/2010; v6.00 PG; release number IX58SZ64)
motherboard, with its one PS/2 keyboard, to work with my old PS/2 mice
with two different USB-PS/2 adapters but very unstable (loses
connections). I also love them because I can use my old KVMs to share my
clicky PC104 keyboard, 19" monitor, etc. to save room. Those KVMs, with
USB ports, are expensive. Now, I have two mice on my desks for two
different computers. :(



Yeah,

I had this mobo with blown ps/2 ports but it was otherwise OK
I of course had no way to enter the bios to enable USB keyboard...
which was disabled by default...(how stupid)

had to toss it
 
B

Brian Cryer

Dishum said:
I've heard of people having problems with a USB keyboard because it's
doesn't work until the OS has loaded the driver, being unable to go into
BIOS or use the boot option hotkey, or press F1 when a fault occurs in
POST. It just occurred to me that I've never used a USB keyboard and I
don't have one with me to try out.

I've experienced this and it can be very frustrating. However mostly there
will be an option in the BIOS to enable the use of a USB keyboard in the
BIOS. I forget what the option is called, and it wasn't something obvious
....

All the PCs I've used when only come with USB (no PS/2 connectors) worked
fine in this respect. So if you are thinking of getting a newish PC/laptop
then I wouldn't expect it to be a problem. (YMMV)

Can anyone please clarify the situation and explain why PS/2 is falling
out of favour?

Good question. Don't know. I think Intel (since 2001-ish) have relegated
PS/2 ports to legacy status, but I don't know the reason. If you look at
Paul's reply he's given a good answer to this one.
 
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D

Dishum

Paul said:
PS/2 for that purpose, is a superior solution, for the
reasons mentioned. The OS always seems to recognize it (unless
the PS/2 port is blown out, by hot-plugging it, and you don't
get too many reports of that type). It just seems to work. And
because it's interrupt driven, the response is instantaneous.
With
USB, the USB bus uses a polling method, to determine if devices
have
info to offer, and if the polling process is delayed for any
reason,
then so is your input delayed. Perhaps the addition of a new
USB
device (just plugged in), can affect the keyboard/mouse USB
response
slightly.

The reason Intel is on such a mission, to remove PS/2, is so
the
SuperI/O chip can be completely removed from motherboard
designs.
At the moment, perhaps the hardware monitor function is all
that
remains of it (once floppy, parallel port, serial ports,
CIR/SIR,
PS/2 are removed). The only bit Intel is missing, is ADC
converters
capable of measuring power supply voltages (which as of today,
would still be an accessory function available on about half
the
SuperI/O chips). And perhaps Intel doesn't think that function
is
worth having, or perhaps Intel doesn't even recognize that as
an
"official" chipset function as such.

Once the legacy interfaces are removed, and all the third-party
chipsets are removed from competing with Intel (by lacking a
license for the bus interface), then Intel provides all the
"intelligent" functions. The only things left on the
motherboard
are peripheral chips (NIC, HDAudio chip, Firewire chip), or
regulator chips (VCore, VDimm regulators). It would mean, for
each motherboard sold, Intel makes the maximum profit from it.

With the recent removal of PCI bus from the motherboard, for
a few years there will be motherboards with a PCI Express to
PCI
bridge. But eventually that will disappear from all boards as
well.
I think Z77 may be the beginning of chipsets for desktop,
without
a PCI bus being available natively. The interface solutions
then
are PCI Express and USB2/3, for virtually everything. Which
means
every time you need a legacy solution (such as when I needed a
serial port for a dialup modem), it's a trip to the computer
store
and forking out $29.95. Same thing happened when I needed a
parallel
port to run a hardware programming dongle - another trip to the
store, and fork out more money, for a PCI Express to parallel
port
card. Interfaces are *so* much cheaper, when they're bundled
with the
motherboard.

Paul

Thanks. I had a sneaking suspicion that it was something along
the lines of what you said, except that I didn't know about
Intel's scheme to eliminate competing standards. The issue has
been muddled by some people who voice the opinion, implied or
expressed, that USB is superior to PS/2.
 

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