USB vs PS/2

User avatar
ShivaYash

12 Jul 2015, 14:10

As a Mac user, does it really matter?

Does PS/2 offer anything in terms of day-to-day usage, over the convenience of USB?

With best,

User avatar
jou

12 Jul 2015, 14:27

Yes, it does matter for a Mac user: Macs don't have PS/2 ports ;-)

User avatar
ShivaYash

12 Jul 2015, 14:29

jou wrote: Yes, it does matter for a Mac user: Macs doesn't have PS/2 ports ;-)
HAHA... but would you suggest using an adapter in order to still 'gain' any special PS/2 only features, or through this process, any such gain(s) are lost?

Ta.

Findecanor

12 Jul 2015, 14:29

Huh? There is no (and has never been any) Macintosh with native support for PS/2... so you would have to use an adapter to USB anyway.

Edit: What gains?
Last edited by Findecanor on 12 Jul 2015, 14:33, edited 1 time in total.

User avatar
ShivaYash

12 Jul 2015, 14:30

ok ok, i get it.

Findecanor

12 Jul 2015, 14:43

The reasons why PC users still use PS/2 are:
- Support for old keyboards
- Free up a USB port
- PS/2 is somewhat faster than Full-speed USB. However, the protocol is only one part of the chain and in practice the speed difference is negligible. Old keyboards don't always utilize the full speed.
- PS/2 supports N-key rollover. There is the myth that USB wouldn't - it does, but not all keyboards or adapters implement it because it is easier for the firmware developer to not to. Some keyboards are limited to 6-key rollover over USB but do have N-key rollover over PS/2. USB 6KRO is actually six arbitrary keys plus the modifiers which is more than enough for most games where you would also use a mouse. Many modern gaming keyboards do support at least 10-key rollover.
If you do use PS/2 and an adapter then you pretty much need to build your own with Soarer's or Hasu's firmware to get N-key rollover because off-the-shelf adapters usually don't.

User avatar
ShivaYash

12 Jul 2015, 15:21

Findecanor wrote: The reasons why PC users still use PS/2 are:
- Support for old keyboards
- Free up a USB port
- PS/2 is somewhat faster than Full-speed USB. However, the protocol is only one part of the chain and in practice the speed difference is negligible. Old keyboards don't always utilize the full speed.
- PS/2 supports N-key rollover. There is the myth that USB wouldn't - it does, but not all keyboards or adapters implement it because it is easier for the firmware developer to not to. Some keyboards are limited to 6-key rollover over USB but do have N-key rollover over PS/2. USB 6KRO is actually six arbitrary keys plus the modifiers which is more than enough for most games where you would also use a mouse. Many modern gaming keyboards do support at least 10-key rollover.
If you do use PS/2 and an adapter then you pretty much need to build your own with Soarer's or Hasu's firmware to get N-key rollover because off-the-shelf adapters usually don't.
Thanks very much!

User avatar
Muirium
µ

12 Jul 2015, 16:04

Aye. It all boils down to 6KRO and other partially true myths. Nothing to drill a hole in your Mac for a PS/2 port about.

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