IBM JX (Picture Heavy)

[SpidersWeb]

Thanks again to mrrad01 for helping me out on this one and getting it shipped down to Wellington for me!
I need to do my Apple II thread too yet, which is going great, but being quite an oddball/rare machine I figured I should through some pictures of this guy up.

So, when the IBM PCjr was released in the US it didn't do very well in the home market. IBM Japan grabbed it and turned it in to a small business machine.



The first thing I noticed with this was the improved keyboard - this is the full keyboard with numeric keypad and the typing feel is fantastic. Like the JR it is also wireless, using 4 x AA batteries but does have a cord option.



Internal expansion was fairly poor. I guess to discourage people from using it as a business replacement to the IBM PC 5150/5160 desktop units - they removed the JR's sidecar system and only provided minimal internal slots.



There are three slots. Top left is an RS232 card, and below it is a 64KB RAM card - the slot it's in appears to be only for use with a 64KB RAM card and is marked "EXRAM64". The card on the right is in the EXRAM128 slot - and provides 256KB of memory (these cards were available in 128,256 and 384) and judging by the battery also provides the user with a real time clock. So with the 64KB built in - we've got 384KB of RAM and a serial port - and now the only upgrade options we can add on is a 5.25" floppy drive top-hat or a 10MB ($NZD1700+ btw) hard drive top hat.



So not much expansion to be had. We did however get to keep the JR's graphics modes (plus a few more) and sound.



In fact that part of the system is so familiar, that "JX ColorPaint" and the built in MS BASIC - still think it's a JR


It is also well known the original BIOS only understands 40 track drives, despite the machine coming with 80 track drives. A later BIOS upgrade with DOS 3.2 magically unlocked the 720KB ability.

Now with that in mind, you may be wondering where my disk drives are. Sadly this was the base model - so no floppy drive module - which also means it's missing the internal attachments. The owner did upgrade it to be 384KB - but never seemed to get around to the disk drive upgrade.

The hole where my big floppy control module should sit is quite clear.


This makes me wonder why the owner chose the JX over a Commodore, Apple, or even Amstrad system. It may have a bit more processor power but ultimately it was a BASIC system.

Some more pictures:


Pricelists

[SpidersWeb]

So the machine is actually a runner, with no real restoration needed (I just realised I posted this in R&R but I'm not actually repairing it).
However now I'm on the track to finding a floppy drive module to hook in because without it, this machine isn't very useful.

The previous owner used it as a BASIC / Cassette system.
Alternatively it might have had the 5.25" top hat - but I'm not sure because if it had that, and was sold seperately, I don't know if that requires the primary FDC module or not. Lot's of questions around that.

[Stargorn]

I love the keyboard! I'm not surprised it feels so nice, it has good quality vintage Alps switches: http://deskthority.net/wiki/IBM_JX_keyboards

[SpidersWeb]

Yeah it doens't quite feel like a Model M or Model F, kind of a mix, but a very good feel (I prefer it over both).
The infra-red doesn't seem to prevent fast typing either. One bonus with the keyboard, is that this machine wasn't only the first IBM with 3.5" floppy drives, it was also the first IBM to use a Mini-6 pin DIN for the keyboard cable - so if I decide to use a cable instead, I simply need a stock standard PS/2 extension lead.

Still hunting for a floppy module, so far my only lead is a unit for sale in Aus, but I can see that costing in the 150-300 range (as parts or complete), and then I'd be taxing a potentially working system for parts to upgrade mine which isn't my favourite way to do things. Hoping to find someone with a dead unit.

Something else that was pointed out to me on another forum - my power supply has a bit of a "belly" on it - and you can just see in the pictures a bunch of solder points underneath. On other units the power supply is thinner, and those solder points make up an EXVIDEO slot - letting you add an aditional 32KB of RAM for the high resolution modes required by Kanji - 720x512 I beleive.

[SpidersWeb]

I got woken up at quarter to six this morning by my dog going completely bananas but was rewarded with this:



mmm floppy drives

[tezza]

Excellent. It has a rather enticing design aesthetic.

Terry

[lizardb0y]

Lovely!

That's a machine one of my school friends had, and I was one of the early bidders on that one. It's great to see it in such good hands

[SpidersWeb]

Cheers

It's now been upgraded to dual 720KB, and the 1986 BIOS upgrade chip has been fitted.
I still have the originals, but the unit from Au that arrived appears to have a dud motherboard.

The second floppy drive needs a repair - I think the disk detect switch is faulty.

Some interesting bits:

- in 360KB mode (original BIOS), the BIOS actually forces the drive to "double step" - almost like it's halving the capacity on purpose. This means it's incompatible with other 720KB drives.**
- upgrading the ROM allows you to boot off 720 or 360. If you boot off a double stepped 360 however, the computer remains stuck in double step mode - so you must boot off a 720 for the drives to behave normal (as far as I can tell).
- it has the same '128K RAM' in DOS issue the PCjr has - requiring a DOS driver to use the extra memory
- it starts in 40 column mode for no good reason (the JR had TV out, this does not, and is clear on the standard monitor in 80 column)

** to get it started, I took some MS DOS 3.2 360KB images, and had ImageDisk write them to a 720 with double step enabled

[SpidersWeb]

Updates for the evening:

- Drive B works correctly in my 386, but not in the JX, however a temporary 1.44 drive was connected and it's fine - so I suspect capacitors on the drive or something similar - another possibility might be a low 5V from the supply (haven't checked yet)
- JX uses a standard 34 pin twisted cable setup - both drives set to DS1 (not DS0) - however the drive selects are reversed at the connector so Drive A is straight through and Drive B has the twist.
- I still can't format 720KB, but after the BIOS upgrade I can boot/read/write 720KB disks no problem
- JRConfig can be used to get around the non-contiguous memory issue the JR also has - but I found using the /S0 option (keep 64KB slow RAM) resulted in system crashes and 5 beeps.
- works just like a pcJR - played a little Leisure Suit Larry with 3 voice sound and 16 colour graphics

So I still have the floppy issue to solve, and my "spare" JX is a dud. But at least I can do stuff with the system now
Another issue is in 320x200 graphics mode my H-Pos seems to be a little off on the display - I'll have to adjust that.

[SpidersWeb]

Quick update, I've now received a 3rd machine thanks to floppylobster.

It has the 5519 expansion unit on it, and is a working system.

It's a very early model, in fact the expansion unit is #24 and the base unit is in the first 500 produced. It came with two EXRAM128 cards inside the expansion unit, and EXRAM64 + RS232 in the base. This gives it 384KB RAM - with 64KB for video (so 320KB).

Being an early model, it does however have the annoying double-step-not-compatible-with-anything 360KB BIOS for the floppy drives. There also seems to be something misfiring, as during the memory test my colour bars temporarily get replaced with the letter L in some spots. I'm suspecting a 74 logic chip somewhere isn't flicking like it should.

The 5.25" drive works (after a clean) but has fallen out of alignment fairly badly - I can get it to format a disk no problem and read/write to it - but sharing that data with another computer is quite the trick. It feels really weird typing "FORMAT C:" on a regular basis and it asking me to Insert disk lol

Anyway, no matter what happens, I have enough parts to have one very nice JX system with spares for the future. Here's two quick photos, notice the 5519 expansion unit has 4 expansion slots - these are full length and have rear access panels - if only they'd have used ISA slots!




Given the serial numbers, I'm fairly confident they sold around ~8,000 units over the entire run. If the serial numbers on the Japanese units start with anything other than '99' - then it's possible there are more.

[xjas]

Congratulations on discovering something I've never heard of and good on you for bringing at least one back to health.

Those are really tidy looking machines. The cases and keyboards seem like they had some serious designwork put in. Aside from the monitor they look like they could have been built by NeXT or Sun in the '90s.

Love the original order sheet with prices. Wonder what "Jesus - ignore the markings" meant?

[tezza]

Yes, I love the design work and the colours too. Nice!

[SpidersWeb]

Congratulations on discovering something I've never heard of and good on you for bringing at least one back to health.

Those are really tidy looking machines. The cases and keyboards seem like they had some serious designwork put in. Aside from the monitor they look like they could have been built by NeXT or Sun in the '90s.

Love the original order sheet with prices. Wonder what "Jesus - ignore the markings" meant?

Cheers

Ah I can't believe I didn't write up my thoughts on that handwritten note!

There is three sets of marks on that page. A 3.5" floppy configuration, a 5.25" floppy configuration with expansion unit, and a non-floppy configuration. The system I received (my first unit) was the cheapest of those options. I believe the "Jesus" was to indicate their shock/frustration regarding the pricing, and "ignore the markings" was to ensure that this sheet wasn't used when the order was filed.

From the other letters etc I got with the machine, I got the feeling he was a home user on a budget, but wanted to make sure the computer in his home was IBM.

[Gibsaw]

Wonder what "Jesus - ignore the markings" meant?

I'm going to hazard a guess and suggest a fellow employee named Jesus ("Hey-Zoos") was having something to do with processing that order.