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PC jr item

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Sharkonwheels

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In that huge stash I bought, is a a huge side-attachment. Dang thing looks like it's got an 8-bit ISA slot popping out of it. Has a DB25F i think, and a toggle switch, with the 2 sides labellled "PC" and the other "jr".

When I opened the thing up, there's no manufacturer, bit it says "R Side"

Pics are attached.
Can't see the writing in the pic, but the "PC" and "jr" is just above the toggle on the white plastic.

Anyone know what the heck this thing is?
I wonder if it goes with this other thing I saw, that looks like it went on TOP of the jr, and this thing snaps on the end covering both. It looked similar how you add a "slice" to an Acorn RiscPC.


Tony
 

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Never mind - after MUCHO digging, I found the "slice."
It's a Racore expansion module. Has another floppy drive, and a RAM board in it.


Tony
 
I could have saved you some digging, but I only check the forum every 2 minutes during the day, not at night. :)

Take a look at http://www.brutman.com/PCjr/pcjr_pictures_3.html - the third image is the 'Rapport' expansion chassis, which is similar to what you have. (Rapport changed their name to Racore, and also OEMed the device to Quadram.)

All of these have the following:

  • Logic to support a second diskette drive
  • Parallel port jumperable to LPT1 or LPT2 (a big deal on a PCjr)
  • Clock/calendar
  • A BIOS 'mode' that makes the machine look more like a PC with respect to the video memory. (That is the switch on the back of it.)

Some of these have a DMA option which provides DMA support for the diskette drives.

There is no RAM inside the board though. Any RAM would be on a card in the expansion chassis part, not the sidecar part.


Mike
 
Not a prob, Mike. It's kinda' fun discovering what some of this stuff is, because let's face it, even 20 years ago I wasn't stoopid enough to buy a PCjr!!

Anyways, yeah, the RAM is in a separate board in the "slice," as Acorn called it. There's a floppy drive in there also. The sidecar portion has a 3v lithium battery (dead, probably) so I assume it has clock calendar.

How do you tell if it has DMA added in?

How much is somethinglike this worth, ya think? I ended up with like 5 PCjr's, so I was thinking of setting up the nices looking one with this, adding the 128KB IBM sidecar (for 640Kb), etc... and setting up a "SuperJr" for fleaBay.

Need any spare units/parts? I can probably toss some at ya at minimal price.
Gotta get 'em out of my way :D


Tony
 
I happen to like PCjrs, so I'll pretend I didn't hear the latter part of the first line. ;-0

The DMA sidecars will have a relatively large AMD integrated circuit on them, which is the equivalent of the Intel DMA controller. The BIOS on them is also different. DMA sidecars on a Jr generally cause more incompatibility problems than they cure so I steer people away from them unless they are just absolutely curious.

A SuperJr can bring in some money on eBay. What you don't sell I'm interested in for the stockpile I've got in the basement. (I run an informal PCjr parts depot for those who have the affliction.)
 
The PCjr was an interesting system atleast.. I can't believe the prices I heard about it but still it was somewhat unique. I got a huge kick out of the wireless keyboard (IR) and that still works fine on mine (could type all the way across my bedroom when I first acquired the unit back in 99) although I couldn't see what I was typing from that distance lol.

lol, I remember you having a large collection (or pile) of PCjr's on the OCMH (http://www.obsoletecomputermuseum.org/helpline/). I think you and T or Walter or someone were talking about all the peanuts which threw me for a loop until one of you told me that was the codename for the jr.

- John
 
Terry had some in 'Computer Hell' to get rid of. I was not able to rescue them. According to the wife, I've rescued too many.

Peanut was one of the IBM internal code names for the project. There were other names too. IBM used different names with different people/groups so that if there was a leak they would know who the source of the leak was.
 
Awww - don't take offense. It wasn't meant THAT way. I'm sure half the stuff I keep, you probably wouldn't give 2 squats about!!

But that's what this is all about - re-discovering, collecting, seeing if you remember how MFM drives were cabled up / terminated / Drive-Selected!

man - talk about cobwebs!

Anyways, yeah, I PM'd ya - I'll set up one SuperJr for eBay, and we'll work something out on the rest. There will be about 4 PCjr's left, all with FDC+FDD, all but one has 128KB internal I think, all have LPT sidecar I think.

I'll get you more info tomorrow or over the weekend when I get a chance to go over this stuff.

EDIT: Hey , Mike, you know the DIP switch settings for the 128kB sidecar? Probably a stupid question?
Lemme re-phrase that - can ya point me to a link for the switch settings? ;)


Tony
 
Switch one is on the bottom, switch four is at the top:

If this sidecar is the first 128K sidecar (fills memory from 128 to 256K), SW1 On, All others off

If this sidecar is the second 128K sidecar (fills memory from 256K to 384k), SW2 On, All others off

Rinse, lather repeat up to 640K
 
Sorry - pretty common for a Jr that is still in use today. I don't consider a lesser machine usable. ;-0

The usual trick was to take an IBM sidecar and upgrade it from 128KB to 512KB. Combined with the 128K on the motherboard/daughter card, you'd get a 640KB system.

I've also seen systems with 736KB, but have not done that modification myself.

And lastly, there is a gem of a PC Enterprises sidecar that adds another 1MB onto the system for use as LIMS memory.
 
What's that switch do on the Racore sidecore? says PC<-->jr ?
What was involved in the 128KB ->512KB sidecar mod? Couldn;t be simply replacing chips, could it?

T
 
Hey Mike, I found a User's Guide and a Tech Ref for the jr.
I assume you guys already have this? Or do I need to scan it before listing it with the jr?

Gotta maximize! This thing cleaned up NICELY!

I'll give ya the item number when I list it so you can see the pics.

I have a keyboard cable, but doesn't seem to work. When I put batteries in the keyboard, it works IR no prob. I assume you don't need batteries when using the cables, as that would be the pinnacle of stupidity.

Tony
 
No need to scan the manuals - there are plenty floating around in circulation. I've not scanned all of my manuals yet, but some of the smaller and less common ones I have already done.

No batteries needed with the keyboard cable. The keyboard cable is fairly simple, so if it doesn't work it is a broken wire or connector on the back of the machine.
 
The MoBo connectors look fine...
I was gonna cut off the connector and put on another, but of course, now with all these boxes in the garage, I have *NO* clue where my wiring toolbox ended up :confused:

That was the cleanest of ALL the jr's - cleaned up REALLY nice.
I'll try the kb+cable on another jr tomorrow, to make sure the port isn't bad.

Thanks for the assist. I'll have a list of available items for you probably tomorrow. I think it will be:

(4) Juniors
(4) parallel adapters
(2) keyboards
(1) power supply

The juniors have all the top covers, and side covers, all have FDD's and FDC's, and I think all but 1 have 128kb.

Tony
 
I would encourage anybody reading this who wants a PCjr to start speaking up ... It sounds like Tony has a few extra, and before I commit them to the parts depot other people should have a crack at them.

Tony - if the parts don't move and you need to find a home for them we'll do that via private messages.
 
It's a nice starter system. ;-0

I like the Racore expansions, but I really hate the way extra sidecars look on them. The dorky 'L' shaped sidecar system just doesn't cut it.

Some of the Racore expansions had 512K of additional memory, so you could get a full 640K system with no extra sidecars. But no system is complete without a second parallel port, speech sidecar, etc., so you'd still have the extras hanging off of it.

My system is configured something like this:

  • Basic PCjr with 128K RAM
  • 8088 replaced with NEC V20
  • Modified IBM memory sidecar to bring total system memory to 640K
  • Clock/calendar on the motherboard using a Dallas 1216E
  • Bi-directional LPT1 and LPT2 (standard for a Jr is just one, and not bi-directional)
  • IBM PC 5150 keyboard attached via a Racore keyboard adapter
  • Bridge-888 parallel-to-SCSI adapter on LPT1
  • Fujitsu 544MB SCSI disk
  • IBM 8x SCSI CD-ROM
  • Xircom PE3 10BT parallel-to-Ethernet adapter on LPT2

And then depending on the day ...

  • Zip 100 (parallel port or SCSI version)
  • ISA bus adapter for my PC Ethernet and SCSI cards
  • Microsoft or Logitech Mouse
  • TMC 850Jr SCSI sidecar -> rarer than hen's teeth, can boot the machine from a SCSI drive.

Some of us Jr heads have had strange competitions where we see how many sidecars and expansion decks we can cram onto a system. I've seen machines with 3 levels and 8 sidecars before.
 
My Tandy system has a Joystick almost exactly like that. Were they universal or did one rip the other off?
 
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