Line Driver Question

Can you include the part number so that the datasheet can be studied?

Sorry, I didn't realize they might be that specific to different application needs. I thought they were about as general as an op-amp or something, just requiring the application to fit within the part's specifications.

I have several part numbers in my small inventory, but I'm at work, and away from my workbench for the day. One part number that sticks out in my mind is MC1488

On another note, How would I test a line driver for basic operation? Feed it a signal and see if the signal appears on the output also?

My take is a line driver maintains the level and integrity of a voltage/signal/etc....

But there's the example that proves you need the specific IC number.

The MC1488 is very specific, it's intended as an RS-232 line driver, to go with the MC1489 RS-232 line receiver. Since RS-232 uses positive and negative voltages, they generally won't be useful except if your need is for positive and negative voltages. I can't remember but they also may not be particularly good sources of current output, instead they are designed for driving long lines rather than loads that put a lot of drain on the lines.

Other line drivers would be designed for other specific standards.

Then you have drivers intended for loads such as relays.

That's about it. Some may invert signal, others won't. If you see the input reflected in the output, they probably are good (though make sure to feed the input with both a "high" and a "low" voltage to ensure that the output really follows the input, since if it's damaged the output might be stuck at some voltage.

Michael

The 1488 is an RS-232 output buffer. It require a bipolar power supply, meaning +12V & -12V.

The part takes 0V to 5V input and outputs -12V to +12V in accordance with the specification for RS-232 serial ports.

The other part is likely the LM-1489. This receiver uses a single supply voltage and takes the +12 -12 input back to TTL 0 to 5 volt levels.

If you wish to drive very long lines, these are not the buffers to use.

300 feet at low baud rates are possible though the higher the speed, the shorter the run.

Today, a differential interface is more desirable. Driving 1000 to 5000 feet is possible. Your old chips are single ended meaning that the voltages are with respect to ground. A differential driver is not ground refered.

I'll have to check and see if I have an MC1489 then. I might actually have a use for the pair.

I collect classic computers and want to archive a lot of my original software onto modern storage formats. There are many interfaces available for classic computers to transfer to modern PCs via RS-232. Since it's impractical for me to get the classic PC next to my primary desktop PC, I suppose I can try a line driver/receiver adapter and a run of spare telephone wire or CAT5 (about 45ft in this case) to get them connected between my workbench and computer desk. That way, if I don't finish the transfers all in one night, I can just roll up the wire between sessions. I won't upset my better half by leaving classic PCs connected up in the den for days.

Thanks!

You can implement the very old Intel hex routine on the ancient computer data to convert the programs to ASCII hex. You then 'print' the ASCII hex to the serial port. The modern computer can (in DOS for sure) have its console redirected to com1. It will appear as if someone typing the ASCII hex very rapidly to the modern computer. I believe that command was 'mode con:=com1:'

You can then use debug to convert the ASCII hex back into binary data and save the program to modern media.

You got it.

A'line' is a name for a long cable.

Graham

Open up those computers, and they'll likely have one or more MC1488s and MC1489s. The only reason they wouldn't is if they are really old, say forty or more years old, or recent enough that the function was integrated into a larger IC, or it used one of the RS-232 line drivers and receivers that came much later but never had the penetration of the 1488 and the 1489.

Wherever there's RS-232, there will be a line driver and receiver of some sort.

Michael

Thanks for the info. I have an original 5150 I can try that on, but the computers I'm referring to are non-IBM. Commodore 64, Apple II, TI-99, TRS-80, etc. There's RS-232 style solutions for these. I just need to implement the connections.

There are 8080 / Z-80 assembly code examples of the Intel hex program, see if you can find these. Of course, if your program to be saved is in assembly or basic or some other printable form, just list it to the serial port.

I did this long ago to move paint formulas for Roach Paint from a Sol S-100 computer to an IBM PC.

The native interfaces on some of those oldies included cassette tape, probably on the Kansas City protocol (frequency-shift bit encoding). Your easiest transfer solution might be to hook 'em into the sound card input/output ports on a modern-ish PC.

The 'original' PC was not equipped with hard drive, nor (except as an extra-cost option) with floppies. It had a DIN plug on the back for cassette tape.