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DECPrinter I Questions

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Vercus

Experienced Member
Joined
Jul 9, 2009
Messages
123
Location
Pennsylvania
Hello all,
I just got a DECPrinter I today, and have some questions about it.

It's got plenty of foam rot, as expected, and there is foam all over the insides. Any tips on an easy way to remove it? I thought of just using a vacuum cleaner or compressed air can to blow it out / suck it up. However, some of the stuff is kinda on there, and would need to be kinda scraped off. However, I don't want to damage anything by using a paint scraper, etc.

Also, since I don't have a PDP-11 yet, would there be a way I could connect and use this with a modern PC in the meantime? I am told it uses an 8-bit parallel interface with handshaking? Not sure how that differs from a conventional modern parallel port printer.

My DOS/Win98 machine has MS Word 5 for DOS on it, which has numerous old printer drivers available, but not the DECPrinter directly. Perhaps another driver would work?

Any ideas where to get wide format tractor feed paper? I've found regular 8.5 by 11, but thought it would be cool to use something bigger.

It's got a button that says "SET VFU" on it. What does this do?

Any thoughts would be appreciated.
Thanks!
Jon
 
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Vercus said:
Hello all,
I just got a DECPrinter I today, and have some questions about it.

It's got plenty of foam rot, as expected, and there is foam all over the insides. Any tips on an easy way to remove it? I thought of just using a vacuum cleaner or compressed air can to blow it out / suck it up. However, some of the stuff is kinda on there, and would need to be kinda scraped off. However, I don't want to damage anything by using a paint scraper, etc.

Also, since I don't have a PDP-11 yet, would there be a way I could connect and use this with a modern PC in the meantime? I am told it uses an 8-bit parallel interface with handshaking? Not sure how that differs from a conventional modern parallel port printer.

My DOS/Win98 machine has MS Word 5 for DOS on it, which has numerous old printer drivers available, but not the DECPrinter directly. Perhaps another driver would work?

Any ideas where to get wide format tractor feed paper? I've found regular 8.5 by 11, but thought it would be cool to use something bigger.

It's got a button that says "SET VFU" on it. What does this do?

Any thoughts would be appreciated.
Thanks!
Jon
Click to expand...

What DEC printer is it? Model number? I'd vacuum as much loose foam out as I could first.
Then maybe using a small stiff brush get as much of the remaining off. You probably won't
get all of it, as some will be in the glue that was used to stick it on. Then I would use compressed air (but not too high a pressure) to get any remaining foam out of hard to
reach areas.

If we knew the model type we might be able to give you a better answer on if you can
use it with a PC. You might have to make a cable.
 
You can scrape a lot of the rotten stuff off with the vacuum cleaner nozzle as you go. A bit of thinners or similar will take the remaining glue off, although be careful if it's stuck to plastic parts (maybe test your chosen concoction on an invisible part first).

These are indeed parallel printers and they're usually hooked up to an LPV11 module in a PDP-11. I should imagine you could hook it up to a PC parallel port somehow, but I've not idea which connector/pinout this thing uses.

VFU is most probably Vertical Format Unit, which ermm... controls vertical formatting ;-) Not sure what features your DECPrinter has in this respect, but think along the lines of vertical tabs and such.
 
Hello again,
I tried hooking it up to my win98/dos machine. I tried "copy file.txt LPT1" and got a write to device error. I then loaded up word 5 for DOS and tried to print with the Diablo 630 driver, and got a "printer not ready" error. So apparently, the interface must be different than modern PCs are expecting. I'll try looking in the back of the unit to see if the serial interface was installed, but I'm guessing it's not, as it as a DB25M connector. I would think if it was serial, it would be a female connector, right?
-Jon
 
Can't suggest much about how the interface is layed out. The LA180 is the same
printer I have two of here. I have never found ribbons in small quantity that are
not very expensive. All my ribbons are dried out. I tried mine connected to my 8e
once and it did print, but very lightly.
 
It looks like I'm going to have to wait to use it til I can get ahold of a PDP-11. I certainly don't want to modify the printer to work with a PC, only to have to reverse it for a PDP, assuming I ever get one.
-Jon
 
Jon,

DB25M is the correct connector for a device wired as DTE (data terminal equipment, as opposed to DCE or data communication equipment that has DB25F). DEC was very good about adhering to the standard. I would bet that you do indeed have the serial option in this LA180.

If you don't want to play with the printer on the PC, then you could connect it head-to-head with your VT100. The VT100 also has a proper DB25M wired as DTE on the back panel. So, you need a DB25F to DB25F null modem cable to connect the two. Of course I have exactly such, but that doesn't help you.

It is very useful to have various DB25 cables, gender changers, null modem adapters, and one of those LED signal breakout indicating plugs for this kind of work. You should start accumulating that stuff also.

I would also bet that the LA180 is set up for 110 baud, 7 data bits, 1 stop bit, even parity. Most old DEC stuff is that way (like my LA34 and 36.) It could possibly be 300 baud also, but nothing faster.

Lou
 
More thoughts -

In dos, you should copy your file to COM1: not LPT:

LPT is the parallel printer port, whilst you have a serial printer. This also means that your printer needs to be plugged into COM1:. Also, the newer PCs have DE9M connectors on the COM ports, so you need the adapters to go to DB25. Somewhere in the garage I have exactly these cables also DE9F to DB25F to be plugged from a PC into DTE equipment.

Also, you must set COM1: up to be 300,7,E,1 as I mentioned in the previous message.

If you think it would be helpful, In about 15 minutes I could plug my LA36 into an old dos laptop and exactly figure out how to set the COM1:

Lou
 
OK, one last thing -

I don't think you hurt the LA180 by plugging it into the parallel printer port on the PC, but it won't work. The LA180's RS232 data signals are on pins 2 and 3, signal ground is 7. Fortunately these are all data pins on the pc printer port. It would be very bad to have grounded the RS232 TX data pin on the LA180. You would be learning about replacing the 1488 line driver that you would have blown.

I just realized that you successfully got your VT100 connected to your PC and transferred the console operation to the VT100. Whatever cable you used to do that is EXACTLY the right cable to connect the LA180 to the PC also. Use the same port on the PC too, just set the PC port to 300,7,E,1.


Lou
 
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Lou - N2MIY said:
OK, one last thing -

I don't think you hurt the LA180 by plugging it into the parallel printer port on the PC, but it won't work. The LA180's RS232 data signals are on pins 2 and 3, signal ground is 7. Fortunately these are all data pins on the pc printer port. It would be very bad to have grounded the RS232 TX data pin on the LA180. You would be learning about replacing the 1488 line driver that you would have blown.

I just realized that you successfully got your VT100 connected to your PC and transferred the console operation to the VT100. Whatever cable you used to do that is EXACTLY the right cable to connect the LA180 to the PC also. Use the same port on the PC too, just set the PC port to 300,7,E,1.


Lou
Click to expand...

I had forgotten I got an LA180 users manual when I got my 2 printers. From this
it sure appears it's a parallel interface as it has 8 data lines, or 7 and parity. My cable
has a Berg connector on the end that goes to the interface card. If you need the
pinouts I can see about posting that. I have no scan capability.

Would DEC have has a serial version of this too?
 
Hey Lou,
Thanks for all the help! It sounds like you've been a real life saver! I'll have to give what you said a try tomorrow.

Tim,
Mine has the DB25M connector, not a Berg connector. Perhaps yours has the parallel interface, where mine has serial?

-Jon
 
Tim,

You should scan that LA180 manual because there are no online copies. I think Al would be glad to put it on bitsavers.

There certainly was a serial option. The FMPS shows it as LAXX-NW in the parts list and the -E suffix units having this option.

Jon,

Please check the dataplate on the back of the printer. It should say LA180 then a dash and two more letters. I suspect you have an LA180-EA which is the 120V/60Hz RS232 version.

Lou
 
Hello,
I hooked it up to com1 and no go. When trying to copy a text file via dos, it says the file was copied, but there is no output. I tried going into windows and setting the mode as instructed, and that didn't help. I tried both 110 baud and 300. When I looked at the plate in the back, it just said LA180, no dash or extra letters. It's made in 1976, and the serial number is 09875. It says 3A, 115V, 50/60Hz.

I don't have the double female connector to hook it up to the terminal, so that'll have to wait til I can pick one up.

Inside, on the back panel connected to the cable, there are 8 dip switches. Right now, number 5 is the only one on. Is this used to set the baud rate, parity, etc? If so, how should I set them?

Any info would be helpful. Sure wish I could dig up a manual.
-Jon

EDIT: I thought I should add, the cable configuration I'm using to connect it is a 9 pin null modem cable into a 9 pin- 25 pin adapter into the printer cable. Just in case that's relevant.
 
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I got a DB25F to DB25F gender changer so I could hook the printer up to the terminal for further testing. It still doesn't do anything. I even configured the printer and terminal for 300 baud, and nothing happens. I've fooled around with the dipswitches inside the terminal which set different permissions and other stuff I don't understand, and no configuration works.

So, there's something wrong with the printer, I just don't know what. Kinda frustrating, as everything I've picked up recently is broken.

I looked at the logic board, and it has a 1488 and 1489 chips on it, which are in charge of communication. Neither looks bad aesthetically. I'm hesitant to start swapping chips, especially since this thing is soldered on, and would be hard to get out (for me anyway).

Any thoughts on how to proceed?

-Jon
 
Jon,

Don't feel bad - most things I pick up are broken too (but I usually know that going in.) This gear is nearing 30 years old, so stuff is going to develop problems.

I assume that you checked the power supply voltages. I always check those first. Beyond that, I think you're going to need a scope. I would start at the input of the RS232 line receiver and start tracing the signal backward. You will want to stimulate the input by pressing keys on the terminal or with a little program on your PC. Use the print set to guide your tracing. When you come to chips that you don't know what do look at the data sheets. Keep working backwards until you find that something doesn't look right. This is probably a good strategy for any troubleshooting.

Lou
 
You don't happen to have a null modem inline for when you were testing the terminal? I
almost always need one of those to connect a terminal. They basically swap pins 2 and 3.
If you do try taking it out. I don't think you would need one for just a printer. Otherwise
was Lou said sounds like what you most likely will have to do.

Welcome back Lou. :)
 
Might I suggest that you get yourself a little rs232 breakout box. it seems that serial comms has as many standards as there are pins. I have a little box with a 25d on each end, 2 rows of LEDs for true/false on each of the standard lines, two rows of dip switches to connect each signal through or to it's partner, or looped back onto itself, and a row of little pins for each signal on the D so if it's really tricky, you can connect with jumpers. I've never had to use the jumpers...yet.
It really helps when you can se the handshaking going on.
 
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