Parallel Port Side Car items

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chuckphd53
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Parallel Port Side Car items

Post by chuckphd53 »

Here are some details on the Parallel port side car !

This unit provides a parallel port that the PC JR did not supply on the main unit.
This allowed users to interface to the readily available impact printers, such as MicroLine, Okidata and others..

Soon after they were introduced the Jr folks found a way to make the board Bi-Directional with a few tweaks.
Below are some pictures of this board mod.

One of the uses that may Jr folks found useful was the addition of the ZIP drives, ie. ZIP-100 flavor.
Klaus Peichl was the author of the PALMZIP driver that is STILL available at his site for use with the JR.
Support Klaus if you plan to upgrade to a ZIP drive and buy a license from him, it is reasonable and supports his efforts.
http://leute.server.de/peichl/main.htm

Shown is the Par Port board with the Bi-Directional mod done.
Note the blue wire is attached from chips:
PIN-15 ZM11 SN74LS174
to
PIN-1 ZM4 SN74LS374

BLUE WIRE ADDED TO COMPLETE THE MOD
Image

BLUE WIRE SHOWN ON BOARD DRAWING PIN TO PIN FOR CLARITY
Image

BLUE WIRE UP CLOSE VIEW
Image

UP CLOSE VIEW, ZM4-PIN1,
HOW TO :
Use flux for best solder flow. And do not heat up the chip pins any more than needed. Rule of thumb, 'get in and get out ' :shock:
Using a solder sucker or solder wick, remove as much of the solder from PIN-1 on the back side of the board as you can.
If you need to do some touch up on the top side with wick do so.
Before you cut the pin, you must remove the solder the best you can, leaving the solder may damage the board via. and traces.
Using some side cutters, small flavor, place the flat side of the cutters to the board and gently with the tip of the cutters
cut the pin at that point.
You should be able now to, on the back side of the board, using tweezers, grab the pin, heat it up with the solder iron and pull it out gently.
If it resists check your cut or allow the solder iron to heat it up properly to melt the holding solder, USE FLUX.
Gently bend the cut pin up and away from the board lifting is slightly ( see the picture ).
You are ready to tack solder a length of wire (28awg is good) to the pin.
See the picture for the example. If you pre-tin the pin with a small amount of solder and wet the tip of the wire in flux, then hold it
on the pin and touch it with your solder iron it should quickly flow and attach the wire, again, 'get in and get out'.
Image


UP CLOSE VIEW, ZM11-PIN15,
Using the same technique as above do ZM11 pin15 in the same manner and connect the other side of wire to that pin.
You are done.
Now just install your side car and test !
Image

Use this file, written by Klaus Peichl to test your parallel port. ( again support Klaus )

Example output of LPT_TEST:
LPT_TEST 0.2 (c) 1998 by Klaus Peichl
---------------------------------------
Parallel port info utility.

Parallel port: LPT1
Port address: 0378
Readback after output: OK
Bidirectional capability: OK, Input=Low!

https://www.pcjribm.com/pcjrfiles/lpt_test.com
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toddvernon
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Re: Parallel Port Side Car items

Post by toddvernon »

Thanks for posting. I'm going to take a run at this mod today!

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Re: Parallel Port Side Car items

Post by chuckphd53 »

super, easy mod. just dont rush it....

Post your result and pics
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Re: Parallel Port Side Car items

Post by toddvernon »

Just made the mod this afternoon. Works great. My board was super dirty so I threw it in the Dishwasher after the mod and retrobrited the case all day. The board works great just giving the sidecar case more time to cook in the sun. As I only use the parallel sidecar for a ZipDrive, I think I might add an activity LED to match my jrIDE led I put on the outside of the case. Not exactly where to path in the led or what logic to use but I think some logical combination of STROBE and BUSY makes sense. Was watching on Oscilloscope today and don't quite have it nailed yet.

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Re: Parallel Port Side Car items

Post by chuckphd53 »

Are you talking about the PAR port activity light ?
That is a GREAT Idea...
I can help work with you on that :)
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Parallel Ports Activity LED lives

Post by toddvernon »

Threw together a quick breadboard of the parallel port activity LED. Looks like reasonable and easy logic.
Test video below!

https://youtu.be/omlV6ZCJmf0

I'll post my design in a day or so. It's pretty easy. Two IC's an LED and a few resistors. Im sure someone better at this me could probably get it down to one IC.

-t

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Re: Parallel Port Side Car items

Post by chuckphd53 »

send me a sketch of your circuit,,, very interested...
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Re: Parallel Port Side Car items

Post by toddvernon »

Emailed you as its a "sketch", I'll post a pretty version in a day or so.

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Re: Parallel Port Side Car items

Post by toddvernon »

Changed it up a little from the last version. Now using STROBE and ACK as the inputs. I had the circuit wrong yesterday doing the OR before inverting the active low signals. This version works perfectly. Going to make a little test board that will attach to the parallel port card.

https://www.dropbox.com/s/82znn4pm6cicr ... D.png?dl=0

I'll post a new video. It now perfectly tracks the zip drive led.

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ZipDrive sidecar access light! It's DOPE :-)

Post by toddvernon »

Finished the parallel port sidecar LED. Made a short video to show it in action.

https://www.dropbox.com/s/1o9te1zh3apx0 ... 9.MOV?dl=0

I ended up going with the plan of drilling holes in the forward part of the parallel port card and mounting two sockets for the chips. Then wiring all the connections. I think if I did it again I would go the daughterboard route, but it did work out. Front of the board is pretty clean but the back with the wires is a little messy for my liking. One byproduct of this mod is the blue parallel port drive light comes up in a random state at initial power on. Once Palmzip loads it's all normal and even reboots seem to keep the state correct. I'm sure I could fix that with some reset circuit but I'm pretty happy with the mod as-is. I keep the zip drive out of site and it all seems pretty period correct (which I like).

Board photos here:

Front:
https://www.dropbox.com/s/yz8anb3ldruxn ... 6.JPG?dl=0

Back:
https://www.dropbox.com/s/inqufyfzsmvzx ... 5.JPG?dl=0

I'm making on mod the circuit. I initially used a 7505 (open collector inverter). That works and a simpler circuit could be done using only that chip and switching to wired-OR layout and a pullup resistor. But, I already had all the components on there and noticed the output of the inverter was only like 2V due to no pullup resistor. I saw that I had a 7404 in my parts bin that is the same chip without the open collector so I changed it out (sockets!) and found the logic level was a normal 5V as was intended.

Again, the takeaway is you can do this mod with one chip and the wiring would be WAY simpler. I'm not going to post that version as I haven't personally tested it but contact me if you like and I'll tell you how to breadboard and test it!

I think Chuck is working on a how-to section of the site, I will post a more complete explanation of how to do this mod if people want to see it!

SUPER FUN, and a very cool little mod. If someone made a little daughterboard it would be very easy to do!

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chuckphd53
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Re: Parallel Port Side Car items

Post by chuckphd53 »

Todd,,

If I were to make a small PCB with gates and LED, is there only the 4 wiresw needed ?

Pwr
Gnd
Strobe
Busy

Really like this
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Re: Parallel Port Side Car items

Post by DoctorOctal »

FYI, all the gates you need are probably on the board already.

I looked for spare gates on the schematic in the PCjr technical reference and only saw one NOR gate available. However, when looking at a board I have on hand as well as photos of other parallel port boards, I see a 74LS00 quad NAND chip that isn’t on the schematic. I suspect that most parallel port attachments out there are of a revised version that includes this chip. I’ve circled the chip in this photo:
74LS00-identified.jpg
The board I have only seems to be using one of the four gates on the chip, leaving three available. I’d suggest using two, one for the logic and one as a buffer. LS TTL is only rated for sourcing 0.4 mA but can sink about 8 mA, so it’s better to sink the LED current. Here’s a schematic where I’ve referred to the 74LS00 as “ZM12”, which is probably its reference on IBM’s revised schematic, wherever it is.
schematic.png
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chuckphd53
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Re: Parallel Port Side Car items

Post by chuckphd53 »

Just out of curiuosity, did you try driving the LED from the first gate , LED and Resistor to ground. Should be enough drive to light the LED and get rid of the second gate ! Brightness ?

I like this nice and simple.
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Re: Parallel Port Side Car items

Post by DoctorOctal »

Just out of curiuosity, did you try driving the LED from the first gate , LED and Resistor to ground. Should be enough drive to light the LED and get rid of the second gate ! Brightness ?
Todd already tried sourcing the LED current, and it worked for him. I imagine it would work for others, too. I didn’t try it myself. However, LEDs often need a few mA for reasonable brightness, and my reading of the datasheets is that LS TTL isn’t rated for sourcing that much current. It can sink 8 mA, however, which should be enough for almost any LED.

I’m shooting for a design that will work for everyone who might try it in the future. If it works for you without the second gate, great, but other people’s results may not be the same. And I wonder how overloading the output might affect the lifetime of the gate.

The second gate is available (with another NAND and a NOR to spare), so why not use it for a more robust design?

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Re: Parallel Port Side Car items

Post by chuckphd53 »

If a formal write up that I could put on the front pages was written up I would give it a formal page.
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Re: Parallel Port Side Car items

Post by DoctorOctal »

I may write formal instructions some day but am far from that point right now. I haven’t even touched my own parallel port yet, there are other things I need to investigate before I do, I have other projects competing for my time, etc.

I just wanted to point out the unused NAND gates I saw before you made any PCBs.

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Re: Parallel Port Side Car items

Post by toddvernon »

My final config with the 3.3V LED and two chips turned out to be only about 6ma so I'm sure about any combination that works would be great. I would suggest using the 3.3V LED's they are super bright at 5V :-)

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