My PCjr Setup & Collection

General discussions on the PCjr

My PCjr Setup & Collection

Postby Tempest » Fri Jan 15, 2010 8:25 am

I guess my first post should be about my PCjr setup and collection. That's why we're all here right?

I've been a fan of the PCjr since I first saw one at my friends house back in 85. His father worked for IBM so they had a PCjr with a fair sized software collection. IIRC his jr had been modified to 640K (I always thought that was standard) and we spent most of our time playing Zyll, Kings Quest, Alley Cat, a Monopoly game (done in Turbo Pascal), World Games, and other Sierra games. We also dabbled around with Animation Creation when we got bored (usually drawing funny faces on his sisters pictures, what can I say I we were 8 at the time).

Fast forward to about 5 years ago. My friend had sold his PCjr long ago (damn!) and I had just bought my new house and finally had the room to start collecting again. I was able to find a PCjr locally and start rebuilding my friends old collection. I've found everything he had except for Animation Creation which seems to be almost impossible to find for some reason (Alley Cat and Kings Quest are just expensive). So here's what I'm running now:

Hardware
-----------
PCjr (modified for 640K) with a Parallel Port sidecar, Thin Font mod and a yet to be identified PcEnterprises chip
PCjr Monitor
PCjr Keyboard (the real one not the chiclet one)
PCjr Joystick
PCjr Serial adapter cable (if I ever need it)

I have the Power and TV adapter sidecars although I don't use them (do you ever need the power sidecar?). I also have the carrying case which is pretty neat looking. I had the printer at one point, but it took a nasty fall from the top shelf and shattered on impact (guess the plastic was brittle after all those years).

I still don't know what the PcEnterprises chip is for. It appears to be some sort of BIOS replacement, but I'm not sure what it does. It might be related to the memory sidecar somehow because my jr boots up to 640K without me having to load any drivers.

Here's a list of the software I own. At the moment I collect pretty much anything that was PCjr specific or made by IBM around that time.

Software
----------
Adventures in Math
Basic
Clock Cartridge
Color Pain
Crossfire
Demon Attack
Electric Desk
Facemaker
Home Word
Jumpman
Kindercomp
Karel the Robot
Lotus 123
Mine Shaft
Mouser
PC Pool Challenges
PCjr Sampler
Pitfall II
Private Tutor 2.00
River Raid
Rocky's Boots
Scuba Venture
Shamus
Touchdown Football
Trivia 101: Introductory Course
Turtle Power
World's Greatest Baseball Game
Zyll

I have some pictures from my game room showing the PCjr.
PCjr (far right): http://www.atariprotos.com/temp/gameroom4.jpg
PCjr software (top shelf): http://www.atariprotos.com/temp/gameroom7.jpg


What I really want to do is transfer programs to my PCjr somehow. I either want to get an expansion chassis and install a 3.5" drive in it or get my ZIP drive working on the jr (but the drivers for that aren't free). I'm also looking around for a PC that has a 5.25" drive on it and can connect to the internet, but no luck there. I also thought about installing a 5.25" drive into my current PC but it's quite new and I don't think the motherboard even has the pins for a floppy drive on it (5.25 or otherwise).

I've also toyed around with the idea of doing the Tandy mod, but I can't seem to find instructions on how to do it. I'm also loathe to do anything that will damage the PCjr case like installing a switch. I might install a V20 chip, but I'm afraid that it will make games play too fast and cause incompatibilities.

Tempest
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Re: My PCjr Setup & Collection

Postby Brutman » Sat Jan 16, 2010 8:20 am

Hi Tempest,

Doing an introduction here is kind of like doing an introduction at a 12 step program. (Or at least how that is portrayed in the movies.)

"Hi, my name is Mike. I am a PCjr user."

"Welcome Mike, how long have you had this problem?"


And so another one joins the ranks.

One correction - the Chiclet keyboard is the real keyboard. ;-0 The replacement keyboard looks nicer and the keys are slightly easier to type on, but it is just as bad and mushy as the Chiclet keyboard. It is literally the same device, but with a different top bezel and keycaps - the membrane is exactly the same. Personally I can't stand either one, and I use a PC 5150 keyboard on mine. The layout is a little more consistent with my 386-40, which has a PC AT keyboard.

Back in the day I thought the serial port was the key to all of my computing problems - anything could be attached to a serial port. I used it for my modem, a direct connection to another machine, or for a mouse. Fast forward twenty years now and I never ever use it anymore - nobody uses a modem, I don't need to use a null modem cable, and I rarely use a mouse on that machine. However, it is still the lowest common denominator for communications so having the adapter is a good thing.

The power sidecar with a second brick is useful for when you have more than 2 or three sidecars on a system. But that is the TV adapter sidecar? I haven't used the television adapter in years, but that looks like a giant RF modulator that connects to a port on the back of the machine. I'm not aware of any sidecar that does that function. What does the connector look like?

Any Jr with enough memory on it will count up to 640K. For some reason the machine was designed to have 128K at most, but yet the BIOS counts up to 640K just like on a real PC. This is not the only contradiction - the BIOS will recognize and use up to three floppy drives even though the limit is one, and it will look for two parallel ports too. To make use of the 640K is a different problem though - unless somebody has modified the BIOS of the machine you will need to load a device driver to force DOS above the hole created by the video buffer. I use Jrconfig for that. The memory hole problem is well documented on the web pages, and Jrconfig is available for download if you need it. There are other such device drivers too. The machines with the Racore expansion units can boot without a device driver, but they modify the BIOS of the machine to do it.

I'd like to find out what is in that chip. Do you have an EPROM programmer by any chance?

Your software collection is excellent. Demon Attack is one of my favorite games for the Jr. I wasted way too much time with Pitfall as well. I have the software for the clock cartridge available if you need it - it is on the web pages. It is not the original software - it is a replacement I coded up. If you have the original software that comes with the clock cartridge I'd like to have a copy to preserve it.

Data transfer isn't that difficult. Here are your options in a nutshell:

  • Create a 'mothership' machine that has both drive types in it. A 386 or 486 is perfect for this as they can support a good sized hard drive and can use the Microsoft DOS networking to get you a drive letter on your more modern machines.
  • Put a Microsolutions Backpack drive on the Jr. These attach to the parallel port. They are available on eBay, and they work great on the Jr.
  • Put an older 720KB drive on the Jr and use a DOS device driver driver.sys to get the size/format correct.
  • Put a Zip drive on the Jr. I purchased the PalmZip drivers - they are worth it. The genuine Iomega drivers will work if you have a NEC V20 CPU. The NEC is a good upgrade to do - it is just slightly faster, but it enables a lot of software that requires the 80286. It implements the newer instructions that the 80286 implements in real mode.
  • Network your Jr! I have Ethernet on mine, and it is not hard to do


Don't worry about the NEC V20. The only game that I know doesn't work with it is LodeRunner, and that can be patched to work. I've not done the Tandy modification, but there are people here who have. You can install it without making a hole in the case - the switch doesn't have to be easy to get to.


Mike
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Re: My PCjr Setup & Collection

Postby Tempest » Sat Jan 16, 2010 2:37 pm

You're right, the TV Adapter isn't a sidecar. It came in a sidecar type box so I guess I didn't take too close of a look at it.

I'm still looking for a mouse for my jr, perhaps a serial mouse would work? I guess you just need the right drivers for it. I'd like one like they show on the Color Paint box.

I'll download that config program for the jr and try it out. I still need to figure out how to get files to my jr though. What's this Microsolutions Backpack drive you were talking about? Do you need special drivers for it?

I don't have thew software for the clock cart, but I do have the entire Electric Desk suite if you need it. I think there are four or five disks altogether and two carts.

My fear with the V20 is that it will speed games up that shouldn't be sped up. Does it have any noticeable affect on games that were specifically coded for the jr? I don't want to make them run faster, just slow games run at normal speed.

Turns out I have two mods in my PCjr (not counting the Thin Font mod). The first one is the mystery PCEnterprises chip which sits right behind the IR receiver. Sorry for the bad pic: http://www.atariprotos.com/temp/pcjr_2.jpg

The second mod is something that was done to the motherboard under the disk drive. Any ideas as to what this does? Looks like they piggybacked an extra chip on top of another one.
http://www.atariprotos.com/temp/pcjr_3.jpg
http://www.atariprotos.com/temp/pcjr_4.jpg

Oh and here's a better picture of my game shelf: http://www.atariprotos.com/temp/pcjr_1.jpg

Tempest
Omne ignotum pro magnifico

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Re: My PCjr Setup & Collection

Postby Brutman » Sat Jan 16, 2010 4:11 pm

A serial mouse works fine. I have used both Logitech and Microsoft serial mice on the PCjr serial port. The older DOS drivers work fine. The mouse featured in Colorpaint is a Mouse Systems optical mouse - a very nice piece of precision machinery from the glory days. If you find one be sure to get the matching mousepad.

The Microsolutions Backpack is a 3.5" floppy drive that connects to your machine through the parallel port. It requires a DOS device driver - it will not be recognized by the machine any other way. So it won't help with your initial problem of getting software transferred to the machine. Take a look at ebay item number 180399212436 - I have purchased a few from that particular seller and was very happy. (He will combine shipping on request, so if you purchase two or more drives it gets to be very reasonable.)

To get stuff transferred you are going to have to build a mothership machine, at least temporarily. If this is not possible it is fairly easy to use a null modem cable connected to the serial port and software like Procomm to move files across the serial port. It is slow, but it is better than nothing. Do you have anything that looks like a terminal emulator or communications program in that stack of software you have? At worst case somebody can send you a floppy to get started. The null modem is a lost art, but once you pick it up and learn how to do file transfers it is not a big deal.

Personally I prefer using FTP over a modern Ethernet, but you need an Ethernet adapter for that. The Xircom PE3-10BT works very well on the PCjr. There is one on eBay right now, but it is missing the AC adapter.

The V20 isn't fast enough to affect game play - I wouldn't worry about it. The speedup depends on the instruction mix, but at best it is a 15% improvement on software specifically designed for it. In normal operation you will see 5 or 10%. Games I think generally benefit less because most of the time is spent updating the screen, and the V20 has no impact there.

As for your motherboard - very interesting. I don't know the PC Enterprises modifications very well. I think that the chip near the IR sensor might be related to the Thinfont modification - I thought the font chip was in that general area. The other modification - god only knows. I'd like to get a better picture so that I can trace it out and see what they were trying to do.
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Re: My PCjr Setup & Collection

Postby Tempest » Sat Jan 16, 2010 4:52 pm

I'll try and get a better picture of the mod tomorrow. I never even knew it was there before today.

What kind of power supply does that Ethernet adapter take? I have that auction on watch, but I wasn't sure if the power supply was something generic or very specific and hard to find.

Tempest
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Re: My PCjr Setup & Collection

Postby Tempest » Sat Jan 16, 2010 4:57 pm

Oh and what kind of driver do I need for the backpack? I have a friend who will put it on a 5.25" disk for me.

Tempest
Omne ignotum pro magnifico

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Re: My PCjr Setup & Collection

Postby Brutman » Sat Jan 16, 2010 5:43 pm

The Xircom needs an adapter that puts out 12VDC, 300MA. A universal adapter probably fits.

As for the Backpack, that one is a new box in shrinkwrap. The DOS device driver is on the CD in the box. It is 13K in size - very reasonable for a PCjr.

I'd start with the Backpack first - that is going to be easier to use.


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Re: My PCjr Setup & Collection

Postby Tempest » Sat Jan 16, 2010 6:55 pm

Ok I tried to get a better picture of the mod, but didn't do a good job. http://www.atariprotos.com/temp/pcjr_5.jpg

The chip on the bottom of that picture (the one that's piggybacked) says 74F86N K8410. The one on the upper left says SN74LSL73N and the one on the right says SN74LS157N. If you stand at the front of the case the chips are actually upside down with the notch on the right. Assuming the upper right pin is pin 1 (looking from the front of the case):

Pin 1 of 74F86N K8410 is connected to Pin 2 of SN74LS157N. Pin 2 of 74F86N K8410 is connected to pin 9 of SN74LSL73N. Pin 3 of 74F86N K8410 is connected to pin2 of SN74LS157N. I'm not sure if this helps any.

Tempest
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Re: My PCjr Setup & Collection

Postby Tempest » Wed Jan 20, 2010 3:50 pm

I just got the Backpack drive today. What are all the files I'll need on a 5.25" disk to make this work? My friend is willing to transfer the files for me, but I need to know which ones I need.

Tempest
Omne ignotum pro magnifico

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Re: My PCjr Setup & Collection

Postby Jim Thomson » Thu Jan 21, 2010 9:54 pm

I'm pretty sure that the piggy back chips are the Tandy 1000 mod.
The chips match those described in PCjr Power.
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