Semi-OT: PC won't start with USB-LPT plugged in

On Sat, 5 Mar 2016 16:34:05 -0800, sms Gave us:

Never heard of an isolation transformer?

The power supply does have +5V standby which keeps some stuff powered so the lithium coin cell doesn't have to power that stuff (never unplug or turn off power via a power strip switch). The CMOS memory, Wake On LAN, and sometimes USB ports may be powered by +5VSBY.

One exception to that rule: UPS. If you turn 'off' a computer and it shares a UPS with other devices, be aware the 'off' computer might still be drawing 20VA (like,

I never measured the power draw when the computer is off. While the +5V STBY can typically provide tens of watts, I would think that the actual power draw would be just a few watts. Have you measured it?

Yes; an old Xeon here, and its monitor, take 15 VA when powered down, and only 2W (but the UPS cares about the VA reading, I'm told).

With the sleeping display unplugged, tht goes to 12 VA, 1W. I've seen other PC power supplies with similar draws.

Shirley you can't be serious?

This gets a +1. Also, the printer could be back-feeding power into the USB port. I've seen all kinds of weird behavior when that's an issue. Try disconnecting the adapter from the printer itself, then powering on.

On Mon, 07 Mar 2016 09:12:49 -0500, JW Gave us:

I do not even remember seeing such a product being released. There was that version *underneath*, when one checked the "windows" information out, But I do not remember a commercial release of "NT 4".

The parallel port does not have any +5 (or any voltage) power pins. Only ground and signal pins.

He said earlier that even with something like a USB battery charger, which draws at least 500mA, that the system starts up.

There could be some humongous capacitor in the device which causes a huge current draw at start-up. That's why I suggested that he try using a powered hub between the computer and the USB-Parallel adapter as a test.

Then run XP. Fuck it. Think of it like driving a 1950 Chevy, unsynchronized manual transmission, no seat belts or air bags. No power steering. Driving those MFs was like work.

So you run XP Pro because they probably won't let you register Home anymore , do ZERO updates unless you need a service pack. Do not update java or IE or anything and the software is so old that a new virus won't run on it. Th row AVG on it and don't use it on the internet. Once all the drivers are in , clone the HD in case you do get hit with a virus. If so, break out the ol d Norton Ghost and reclone it from the working image, which would also run but you don't want to do that.

I am going to spend the rest of my life avoiding software "upgrades". Every upgrade removes something I want and some put in shit I definitely do not want. They will pry XP out of my cold dead fingers.

Plus, the fact is that Windows 7 is far better than XP ever was. It was Windows 8 that had issues, and even though those were corrected pretty quickly, it retained the bad reputation.

When I go to embedded seminars, almost everyone is running Windows 7 now. Even the outliers that show up with Macbooks are running Windows 7. They avoid Windows 8 because some of the embedded tools have issues, though these may have been corrected by now.

I had one Windows 7 issue, an HP scanner, that was not that old, would not work. No one provided updated drivers, not Microsoft, not HP. Even in compatibility mode it would not work. Yet if I booted the same machine into Linux it worked just fine.

Jorge should actually thank me regarding the parallel port sticking around as long as it did. At one time in the 1990's, Microsoft proposed to deny WHQL certification to machines with serial or parallel ports. There was a big outcry by computer makers and chip makers because so many customers had serial and parallel peripherals. We had a pow-wow of manufacturers up in South Dakota, hosted by Gateway, and we pushed back against Microsoft's idea and they relented. Without WHQL certification, system vendors would have to pay significantly more for OS licenses. I understood Microsoft's position because at that time they were dealing with a slew of compatibility issues with Windows 95, ISA, and Plug N Play (AKA "Plug N Pray") and WHQL was an effort to improve the Windows experience.

Even now, a lot of commercial users are still using older peripherals like receipt printers, scales, and scanners that require the older interfaces, so a lot of thin client machines have retained these ports as an option, i.e. Wyse offers "Legacy connectivity (adds two serial ports, 1 parallel port and 1 PS/2 port" .

On Mon, 7 Mar 2016 10:01:41 -0800, sms Gave us:

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I hate it, but there are no more MOBOs with floppy 2.88 support any more.

That was the only implementation of the floppy paradigm that actually worked long term reliability wise. I could write a 1.44 floppy on one machine and have it fail to be readable on another. They were so loosely implemented.

The 2.88s never had any such problem. They were the best design ever at the time.

Sure I am.

Not sure but not audibly. Meantime I found that one of my Hubs hub fixes the problem (so far). Amazon 4-Port Ultra Mini Hub, isn't even powered. But I'll have to try a week or so because sometimes stuff rears up again later.

I found that a passive Amazon USB hub so far works. I really don't want to make a science project out of this (can't run the printer sans PE) and this hub seems to be the trick. For about five bucks, not bad. Will keep testing it.

Yes, but what finally did it (so far, knocking on wood) was a cheap Amazon 4-Port Ultra Mini Hub. Non-powered! Beats me why.

Data communications was never a problem with this LPT adapter. With the first three it was (they only worked with XP and not at all with Windows 7).

I'm assuming he meant NT 4.0.

A lot of the problems with parallel ports on newer machines are due to the lack of a PCI to ISA bridge that retains the old parallel port addresses of 0x378, 0x278, or 0x3BC. The way around that was to use a proper USB-Parallel dongle with a driver that retains those addresses, virtually.

Printers generally worked fine, but devices that took advantage of bi-directional mode on the parallel port often had issues. Or, as my colleagues from Israel who wrote the data sheet called it "ECP Backward Read Cycle."

Obviously the problem you had was not related to the OS since the adapter works via a hub.

The people with old software that require a parallel port dongle key were in a world of hurt when the ISA-based parallel port disappeared. And even before that. One device I supported at National was perfectly compliant with the IEEE 1284 spec, but we had lowered the Voh level to close to the minimum level for three good reasons, the move the 3.3V parts, EMI, and to meet the termination requirements. The dongle makers, who extracted power from the signal pins to run the micro-controller in the dongles were unhappy about this since their dongles no longer worked. Tough luck for them since no one ever told them that trying to harvest power from signal pins was kosher.

On Tue, 8 Mar 2016 07:17:55 -0800, sms Gave us:

Where is a good electronics rabbi when you need one...