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Universal Parallel Bus -- why not?

Started by GreenXenon March 20, 2010
Hi:

I keep hearing about Universal Serial Bus [USB]. Why hasn't a
Universal Parallel Bus [UPB] been implemented yet?

Wouldn't a UPB be faster than a USB at the same clock rate? If so,
this would mean the same speed with less energy comsumption. Right?


Thanks,

Green Xenon
GreenXenon wrote:

> Hi: > > I keep hearing about Universal Serial Bus [USB]. Why hasn't a > Universal Parallel Bus [UPB] been implemented yet? > > Wouldn't a UPB be faster than a USB at the same clock rate? If so, > this would mean the same speed with less energy comsumption. Right? > > > Thanks, > > Green Xenon
Yes it would be how ever, that cost more..
On Mar 20, 8:38=A0am, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
> GreenXenon wrote: > > Hi: > > > I keep hearing about Universal Serial Bus [USB]. Why hasn't a > > Universal Parallel Bus [UPB] been implemented yet? > > > Wouldn't a UPB be faster than a USB at the same clock rate? If so, > > this would mean the same speed with less energy comsumption. Right? > > > Thanks, > > > Green Xenon > > Yes it would be how ever, that cost more..
Significantly more?
You're 30 years too late.  They called it the Parallel Port.  Used on 
everything.

Its fundamental limitations are: 1. attached to the 8MHz ISA bus (baud < 
~1Meg/s), cable length or signal quality (limited to about 1 meter), and the 
cable contains 25 wires = it's a heavy bastard and requires lots of 
connections = more to go wrong.

I suppose one could make a PCI or PCI-E clocked "parallel port", maybe using 
LVDS and terminated transmission lines, but then you'd be right back at 
something like 100MBit ethernet (CAT5 = four parallel pairs).

USB has only four wires.  They fit nicely into a robust connector.  Can't 
beat that.

Tim

-- 
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"GreenXenon" <glucegen1x@gmail.com> wrote in message 
news:658ff416-fea2-4105-b402-8e91f04cce93@a37g2000prd.googlegroups.com...
> Hi: > > I keep hearing about Universal Serial Bus [USB]. Why hasn't a > Universal Parallel Bus [UPB] been implemented yet? > > Wouldn't a UPB be faster than a USB at the same clock rate? If so, > this would mean the same speed with less energy comsumption. Right? > > > Thanks, > > Green Xenon
On Sat, 20 Mar 2010 10:38:44 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

>GreenXenon wrote: > >> Hi: >> >> I keep hearing about Universal Serial Bus [USB]. Why hasn't a >> Universal Parallel Bus [UPB] been implemented yet? >> >> Wouldn't a UPB be faster than a USB at the same clock rate? If so, >> this would mean the same speed with less energy comsumption. Right? >> >> >> Thanks, >> >> Green Xenon >Yes it would be how ever, that cost more.. >
Against my better judgemnet, since I know GX is just a troll, I will answer his question... When you have one signal line, and you send a bit, then once you are able to determine the status of that bit, you are ready for the next one. You can do this very quickly. However, when you have two lines, then you have to be able to know, not just the status of one of those lines, but that of both of them, at the same time. This takes a little longer to be certain, and therefore, it goes slower. One line or the other may be a little longer, or have a slightly different impedance, or any number of other reasons that makes it different. Yes, this is ofen more than twice as long as for a single line. As you add signal lines, the problem grows. You have to wait till you can be sure that ALL the lines have reached the correct state, before you can move on to the next. Now, you may think that this doesn't grow too fast, and you are right. But, at the same time, your hardware has also increased. Your clock speed has gone down, and your hardware cost has gone up. This makes a parallel signal not very attractive So, how do you get faster throughput? You use multiple serial lines, like LVDS, each taking a part of the flow, and add them all togther at the the other end. Charlie
On Sat, 20 Mar 2010 07:33:19 -0700 (PDT), GreenXenon
<glucegen1x@gmail.com> wrote:

>Hi: > >I keep hearing about Universal Serial Bus [USB]. Why hasn't a >Universal Parallel Bus [UPB] been implemented yet? > >Wouldn't a UPB be faster than a USB at the same clock rate? If so, >this would mean the same speed with less energy comsumption. Right? > > >Thanks, > >Green Xenon
At very high speeds you start to get skew in the prop delay between different data lines of a parallel bus... the bits arrive at the destination at different times. The higher the clock rate and the longer the bus, the worse this problem gets. A signal traveling over a single twisted pair has no skew problems. And electrical losses/dispersion can be fixed with per-lane adaptive equalizers. For higher data rates, you add more lanes, each with its own transmitter/equalizer/receiver/fifo, and merge the data streams digitally. So long, fast serial busses scale much better than parallel busses. They are smaller and use less connector and IC pins, too. John
On 20 Mar., 18:25, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 20 Mar 2010 07:33:19 -0700 (PDT), GreenXenon > > <glucege...@gmail.com> wrote: > >Hi: > > >I keep hearing about Universal Serial Bus [USB]. Why hasn't a > >Universal Parallel Bus [UPB] been implemented yet? > > >Wouldn't a UPB be faster than a USB at the same clock rate? If so, > >this would mean the same speed with less energy comsumption. Right? > > >Thanks, > > >Green Xenon > > At very high speeds you start to get skew in the prop delay between > different data lines of a parallel bus... the bits arrive at the > destination at different times. The higher the clock rate and the > longer the bus, the worse this problem gets. > > A signal traveling over a single twisted pair has no skew problems. > And electrical losses/dispersion can be fixed with per-lane adaptive > equalizers. For higher data rates, you add more lanes, each with its > own transmitter/equalizer/receiver/fifo, and merge the data streams > digitally. So long, fast serial busses scale much better than parallel > busses. They are smaller and use less connector and IC pins, too. > > John
and toggling a wide bus slowly will use just about as much power as toggling a narrow bus fast so theres no magic gain in efficiency -Lasse
On Sat, 20 Mar 2010 07:33:19 -0700 (PDT), GreenXenon <glucegen1x@gmail.com>
wrote:

>Hi: > >I keep hearing about Universal Serial Bus [USB]. Why hasn't a >Universal Parallel Bus [UPB] been implemented yet?
It has. It's often called the "Printer Port".
>Wouldn't a UPB be faster than a USB at the same clock rate? If so, >this would mean the same speed with less energy comsumption. Right?
No. and HELL NO.
On Sat, 20 Mar 2010 08:38:56 -0700 (PDT), GreenXenon <glucegen1x@gmail.com> wrote:

>On Mar 20, 8:38&nbsp;am, Jamie ><jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote: >> GreenXenon wrote: >> > Hi: >> >> > I keep hearing about Universal Serial Bus [USB]. Why hasn't a >> > Universal Parallel Bus [UPB] been implemented yet? >> >> > Wouldn't a UPB be faster than a USB at the same clock rate? If so, >> > this would mean the same speed with less energy comsumption. Right? >> >> > Thanks, >> >> > Green Xenon >> >> Yes it would be how ever, that cost more.. > >Significantly more?
Of course, look at the old Centronics port printer cable compared to a modern USB cable. A common fast parallel bus was the SCSI port for HDDs, and these days they use SAS (Serial Attached SCSI) because it's faster than old parallel form, which went from narrow, wide and ultrawide before going serial to run even faster. And the reason is as other posters state, data skew between parallel lines limits max data rate. It's faster to go serial. That's why hard drives now use SATA rather than the old ribbon cable. USB is also self powered, it grew from the serial keyboard connection where the requirement was met by four lines: power, data, clock and ground to get the cheapest hardware solution. Also, USB's self clocking gets rid of the old serial port's parameter setting issues. Grant.
On Mar 20, 7:33=A0am, GreenXenon <glucege...@gmail.com> wrote:
> Hi: > > I keep hearing about Universal Serial Bus [USB]. Why hasn't a > Universal Parallel Bus [UPB] been implemented yet? > > Wouldn't a UPB be faster than a USB at the same clock rate? If so, > this would mean the same speed with less energy comsumption. Right?
Look up IEEE-488 It was an attempted semi-universal parallel bus system. It had several problems. One being that the specs were written by lawyers. They were very hard to understand. There was also one part to do with the serial pole method that was ambiguous. Two systems could comply but not be compatible with each other.