General discussion


Pushing the limits....backwards

By GuruOfDos ·
MS and the hardware makers keep adding new features, new enhancements and even more bloatware, but at the same time, they are also removing things, and not always telling us.

Computers have two, and ONLY two, root functions. Processing information (be it matehmatical, text, graphical or whatever) according to defined parameters (input, program and output). That's one. The other.....CONTROL!!!

And where is the control??

1980s....CBM Pet, Vic20, etc had a 22-way connector on the back called, oddly enough, a USER PORT...hook up your electronic circuits, PEEK and POKE a few bytes and hey presto...CONTROL!!! Robot arms, central heating, alarm systems, whatever!!

1990's.... The IBM PC has IO mapped addresses for hardware sat on the ISA bus...&H300=&H3FF was defined as a 'Prototyping Area' and you could build hardware and talk to it with INP and OUT in GWBasic, or IN and OUT in assembler. I design and build ISA cards that do all kinds of 'magic'.

2000' more ISA, and OS's that DON'T allow direct reads and writes to hardware registers or addresses. I'm still having to use 9x because this WILL let me talk to the hardware directly but now my new PC doesn't have ISA slots so where does that leave me?? Hooked up to the LPT port because that still has 5 TTL Inputs and 8 TTL outputs. Need more?? Add another PCI printer port card!!!

Now everyone has Firewire, USB2.0, and suchlike and the powers that be say that the LPT port (and COM ports) are about to become extinct. So where do we go from here? Stay with 'obsolete' technology or move over to dedicated process control electronics which then takes away the computer front end? Are we only going to end up with half a computer...all process and no control? All right, it's a faster, better machine but has progress taken away one of the two fundamentals of computing...the ability to communicate with the 'real world'?

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Perhaps a better title....

by GuruOfDos In reply to Pushing the limits....bac ...

'Losing Control'??
'I forget the last time I had a good POKE'??
'Lead in my pencil, but no-one to write to'??

oh dear.....back to work!!!!

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Firewire to Serial Adapter..

by admin In reply to Pushing the limits....bac ...

Maybe will become a hot item in control? I have an old friend who started in the military with silo controls.... He went on to work for a food processing corporation, mainly refrigeration control automation... I should look him up and ask him. Also CNC and Robotics people have to be using something in the future. I wonder if PC's are just becoming more specific in their purpose in business computing and control computers are also becoming more specific although I don't see them in my work much.It is an interesting topic, although I have no clue at the answer. :)

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Good old Belkin

by GuruOfDos In reply to Firewire to Serial Adapte ...

Yes, and Belkin do make a range of USB to serial or parallel interfaces, so you can still get some legacy I/O on a 'reduced legacy' 'puter. So now if I want 24 lines of DIO it's an expensive industrial PCI card or a USB hub and a pile of USB to LPT adaptors!!! More spaghetti cabling to knit!!

Must dash...I have to **** the dust of an old 486 because the weather has turned chilly and I need to fire up the heating!!

Mike :-)

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Industrial Computing

by TheChas In reply to Pushing the limits....bac ...

Hi Guru,

There are numerous firms that make PCI I/O cards that do just what you are looking for.

The "common" use of these cards is industrial computing. Be it testing, or process control, you can do it all with these cards and their software.

The only problem is that the cards are not cheap.

A couple of manufactures to get you started:

Data Translation

A general resource:

They have several articles on computer control.



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Thanks for that

by GuruOfDos In reply to Industrial Computing

I hear you there. We have used a company called Industrial Computer Source in the past. As you say, these products are 'not' cheap!! In fact one good PCI card to give us a few digital I/O ports often costs more than the rest of the PC!!

The otherproblem with industrial components is the term 'industrial'! They look it! A 19" rack case with an 'industrial' mobo and associated tackle LOOKS like it belongs in a car assambly line or food processing factory!!

Oh for the glory days of ISA, when a few 74LS TTL chips and an 8255 PIO was the basis of 'do-it-yourself' interfacing. So long as you could find a few addresses spare in the prototyping area (&H300-&h3FF) between the sound card, midi port and printer/serial ports the sky was the limit. At 8Mhz bus speed, timing, slew rate and Plug and Pray were not an issue!! I had a VT 286-12Mhz PC back in the late 80's, and the manual gave enough information on the ISA bus to allow you to design your own cards! Try finding the same amount of information on PCI. It's out there, but it's a whole hill of beans more involved and not for the faint-hearted!

Mike :-)

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Left field

by MC_User In reply to Pushing the limits....bac ...

OK, I may be showing my ignorance here but a strange idea came to me while looking into this. Can you use a MIDI controller to access and control your analog devices? It is after all an interface designed to accept multiple analog signals, interpert, control and then act on those signals. Am I really way out bounds with this line of thought?

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Interesting Idea!!

by GuruOfDos In reply to Left field

OK....our devices are digital, not analogue so we use TTL level inputs and outputs. Inputs are from switches, pushbuttons etc, and the outputs control relays, motors, etc.

MIDI is a character-based optically isolated serial system and as such is not really suitable for direct control. It IS feasibly possible to use MIDI, but it would need a microcontroller at the interface end to interpret MIDI messages and convert them to digital signals and vice versa.

While we're looking at that 15 pinconnector though, the gameport 'could' be used for analogue input, of sorts, but you cannot directly inject a voltage into the three analogue inputs (x,y and z). The joystick inputs actually use a voltage reference and a capacitor and use the wiper position of a potentiometer to create an RC oscillator with the time constant (or frequency) dependent on the joystick position, which is then 'decoded' using a binary counter, a DAC and a comparator using the successive approximation method. You would need to use a digitally-controlled potentiometer IC to achieve any useful input function.

Nice idea though! Good to see some 'lateral thinking'!!

Mike :-)

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Great "rant" - I enjoyed it. :-)

by SamLowrey In reply to Pushing the limits....bac ...

I wish I had your knowledge of hardware. I started in DOS, but I never did the things you speak of.


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Even NT can be made to support USB ...

by vicki.laidlaw In reply to Great "rant" - I enjoyed ...

As an installer responsible for modified NT-based systems, I was amazed to discover that Windows NT 4.0 can now be "forced" to accept USB devices with the use of a special hub. That's something I thought I'd never see...

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Ah but....

by GuruOfDos In reply to Even NT can be made to su ...

Using NT precludes the use of directly reading and writing to hardware. Port Reads and Writes to absolute IO addresses via software (e.g.IN and OUT under assembler, or IN and OUT in many dialects of BASIC) requires bypassing the protection that NT has in place and using 16 bit code....something that NT is not happy with!

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