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Ibm pc jx

jmetal88 said:
Have you added a DRIVPARM command to your CONFIG.SYS? If not, that might be your issue there.

http://www.computerhope.com/drivparm.htm
Click to expand...

Another option is to run SETBPB35 from AUTOEXEC.BAT or the command prompt:

ftp://ftp.oldskool.org/pub/tvdog/tandy1000/misc/setbpb.zip

This program will set the device characteristics for the A or the B diskette drive to indicate that the drive is a 720K drive instead of a 360K drive. It requires DOS 3.2 or later.

The only command line parameter is the drive letter (A or B).

For example, to indicate that your B drive is a 720K 3.5" diskette drive:

SETBPB35 B
 
Something else I noticed - on the 256KB RAM card (which takes the system to 384KB total) there is 4 RAM chip slots left - I think these may take 41256's turning it in to the 384KB card (taking the system to a total of 512KB) - so I'll have to take a look at that, and also how to read data from the RTC it has on it.

Edit - Update: these RAM slots have two extra pins, I'm 75% sure 41464's will be what needs to get installed, once I find them I'll try it out.
The 4 sockets sit parallel to the bank of 8 41256 chips, and have capacitors in the same location (above) as the 41256 chips do. I haven't checked the traces, but I'm fairly confident they're 41464 sockets.

But the real job to do is to get that second floppy drive working reliably again in the JX - so I can get it all closed up.

jmetal88 said:
Have you added a DRIVPARM command to your CONFIG.SYS? If not, that might be your issue there.

http://www.computerhope.com/drivparm.htm
Click to expand...

Cheers :)
Sadly I don't think you'll find this in DOS 3.2, but I'm sure that is the issue.
I'm not sure why Computer Hope marks everything as "All DOS Versions".

vwestlife said:
Another option is to run SETBPB35 from AUTOEXEC.BAT or the command prompt:

ftp://ftp.oldskool.org/pub/tvdog/tandy1000/misc/setbpb.zip
Click to expand...

Thanks for that :) It didn't bother me too much but having a small tool I can pop in AUTOEXEC.BAT is something I'll certainly do.

geoffm3 said:
On a PCjr, it is possible to do some low-level debug by holding down a combination of joystick buttons. Doing this it will spit out some post codes to the serial port if your display is dead. Not sure if the JX has this facility or not, but it wouldn't surprise me since they seem fairly similar. I used this while resurrecting my PCjr. On it though it would at least beep, but display was dead. It ended up being the CAS delay line.
Click to expand...

Awesome. I'll keep that in mind for the future, I do have a JX joystick :)
But I currently don't have any plans to put too much time in to the second JX as I don't have any floppy drives, spare keyboard, or spare display for it.
 
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New Zealand based review from 1984 - 4 pages - which provides some interesting information:

https://archive.org/stream/nzbitsandbytes-4-03/NZ-bits-and-bytes-issue-4-03#page/n39/mode/2up

With some tidbits from that, I think I may be able to use my additional memory card in a 5519 expansion unit to bring the system to 640KB or higher - with some help of the tools used on the PCjr.
It's also interesting the article refers to the drives as single sided, which I'll admit to having read before elsewhere, however I was writing and booting from double stepped double sided drives.

Another key part of the article is it mentioned you could buy disk-less versions for networks of up to 64 machines running from an IBM PC XT. Something I've never even heard of for the JX.

There is also an IBM NZ advertisement for the JX in that magazine around page 3.
 
SpidersWeb said:
I'll make some images of the ROMs at some point.
Would be keen to get a copy of JX DOS 2.1 if anybody has it? Currently booting generic MS DOS 3.20.
Click to expand...

I have the original JX PC-DOS 2.11 (weird 360kB format) and JX PC-DOS 3.21 lying around somewhere at my parents' house. I'll look for them.

I also have the original ROM; when my dad bought JX PC-DOS 3.21 it came with a new ROM chip so that it could boot off of 720kB diskettes. He kept the original ROM. I don't have any way to read it, though.

I also have an attractive case that the original software came in. There is some other random software with PC JX branding (I think Personal Editor II?)

I have a bit of a soft spot for this machine, as it's the first machine I learned to type and to program on. When we moved to America, we "downgraded" to a PS/2 Model 25 with PC-DOS 4.00. I was pretty disappointed I had no more 3-voice sound, nor SCREEN 3/5/6 in BASIC. (Did anyone ever figure out what made SCREEN 4 different than SCREEN 1?)
 
So I got another one today, this time with a 5519 expansion unit and 5.25" floppy drive.
I'll do a better write up and probably a video in an upcoming weekend but thought I'd share some bits of info in the meantime.

The expansion unit contains it's own 40W power supply triggered by the system below (it actually has an exterior cord that piggybacks). The 5.25" drive just connects to the controller in the base unit - this is useful information as it means you can add a floppy drive using a standard floppy cable and seperate power without needing to buy a 5519 if desired. The expansion unit connects to one of the expansion slots in the base machine - but has four slots inside itself - inside mine I found two EXRAM128 cards.

It was a very early model, with a serial number in the high 400's, the expansion unit serial number is '99-00000024' so I suspect that was quite quick off the assembly line also. The downside here is it has the annoying 360KB dual-step (not compatible with anything) BIOS running the floppy drives - switching it means removing the expansion unit and the complete floppy system from the base unit. It's also a Mask ROM - so anyone looking to buy a JX - be prepared.

My 5.25" drive is out of alignment on it - but after a clean it formats disks perfectly - just can't get consistent results with data transfers between machines. So with the misaligned 5.25, and the 3.5 on double-step only, I haven't done full testing or got any game disks created. One problem it is suffering, and perhaps your JR guys might recognise the issue, is during the RAM test the coloured bars often get replaced with the letter L temporarily - my other running JX does not do this. I'm wondering about this because it may mean I need to switch around more parts if there is a fault.

The 5.25" drive is "C" which I'm sure most of you guessed. Does feel a bit weird Formatting C all the time though.

Quick pictures:
CJc8d_bUwAACIus.jpgCJboIXVUMAAfQem.jpg
 
A question for SpidersWeb:

The current MESS romset for the PC JX includes what purports to be a dump of the 8x8 character generator ROM. This is what it looks like:

pcjx_cga_chr.PNG

The character set at the top is the usual CGA/PCjr 'thick' font, but the other one is *not* the same as the 'thin' CGA font (characters are narrower, and some of them look rather bad). This could be interesting for my oldskool font conversion project, so I guess I'd like to know if it's authentic.

Why I suspect that this dump is not reliable:

- its current MESS status is 'baddump' (may simply be a placeholder?)
- an identical font exists in the ATI Small Wonder (link)

Since you now seem to own a sizable percentage of the world's supply of JX machines, would you be willing to make a dump of the character ROM to verify this? :)
 
As per PM I'll get on to this over the weekend.

For what it's worth, looking at that image, I'd say the top font in 40x25 is what my machine starts up in.
My machines (2 run, 1 dead) are however the NZ/AU versions, not the Japanese Kanji models, so that may be a factor.

IMG_0196_zpsdhways6f.jpg



While I'm here - quick update on these. Since this thread, they've really just been sitting there and my main finished unit getting the occasional boot.

System with Expansion Unit - does not have 720KB support, startup visuals have a glitch during RAM test, 5.25" drive non-operable but it tries!
My first JX - has "720KB" ROM installed, one floppy drive works, currently in storage
Never working system - in storage for parts - failed motherboard

So my mission this weekend:
- repair/replace 5.25" drive in expansion unit
- use software to record ROM images as required (on easily readable 5.25" 360KB floppies)
- spend hours trying to work out how the expansion unit comes off
- switch motherboards between "first JX" and "system with expansion unit" (provides 720KB ROM as well as hopefully removing the memory glitch)
- attempt to use my selection of cards to bump memory to 512KB
- redo the ROM reads on the new motherboard
- locate beer
 
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IBM PC JX (Japanese Model) Kanji Font Rom is still not dumped it.
I think this model is Not so interested in.
I can't understand why MESS team added incomplete system.
 
I have finally dug out a couple of these JX machines. One is a single unit with 256Kb ram and one 3.5 floppy. It has a very old bios rom i.e. 8527K1.. So it only supports 360Kb floppies. The other has the expansion unit, but only has 128Kb ram with one 3.5 floppy in the main unit and one 5.25 floppy in the expansion unit. It also seems to only support 360Kb. One of these came with a letter from IBM where the previous owner was getting the 720k upgrade ROM with JX Dos 3.2 It tells you how to format floppies in 720Kb if that is still an issue for some.. I'll attach an image of the letter here..IBM Letter.jpg

I need to upgrade the rom bios.. Iv'e reached out to Anthony Becket see here http://www.thepcmuseum.com/ibmjx/ He is looking at his rom and rom images..
Rgds,
Simmi
 
Another update on a long dead topic!

Another update on a long dead topic!

I have finally dug out a couple of these JX machines. One is a single unit with 256Kb ram and one 3.5 floppy. It has a very old bios rom i.e. 8527K1.. So it only supports 360Kb floppies. The other has the expansion unit, but only has 128Kb ram with one 3.5 floppy in the main unit and one 5.25 floppy in the expansion unit. It also seems to only support 360Kb. One of these came with a letter from IBM where the previous owner was getting the 720k upgrade ROM with JX Dos 3.2 It tells you how to format floppies in 720Kb if that is still an issue for some.. I'll attach an image of the letter here..View attachment 63774

I need to upgrade the rom bios.. Iv'e reached out to Anthony Becket see here http://www.thepcmuseum.com/ibmjx/ He is looking at his rom and rom images..
Rgds,
Simmi
 
I had one of these in the 1980s. I still have some of the materials from it, including the old ROM, I need to check the part number. It would be the old ROM that only supports 360kB. It was upgraded to a newer ROM that supported a fixed disk (it was 10MB) and 720kB diskettes.

It came with PC DOS 2.11 and then when it was upgraded to the newer ROM, that came from PC DOS 3.21, which fully supported 720kB disks, unlike the partial support with different drive letters detailed in your letter. Out was, I believe, the " "Power" - 512k RAM, 2x 3.5" Drive and a Clock" model.

Eventually I'd like to find one of these in the U.S. (or find one in Australia and bring it back with me). When my family moved to the U.S., we left it behind since it ran on 230V/50Hz, and it still had a good resale. We "upgraded" to a PS/2 Model 25, which felt like a downgrade since PC DOS 4.00 did not seem superior to PC DOS 3.21 and BASIC did not support any graphics modes beyond CGA on the Model 25/30, whilst BASIC on the PC JX supported the Tandy/PCjr style graphics modes.
 
After a looong time and a pandemic in between, I've sorted out all issues that plagued my Japanese JX:

The keyboard

It stopped working and once openned (see first messages of this same thread) I found the little DIN connector PCB deeply corroded by old batteries. It worked some days with new batteries and using the IR connection; but suddenly, it failed.
Now after quite some years and after quitting looking for pics of this PCB, finally I've disassembled and cleaned thoroughly this little PCB with white vinegar sessions, abrassives and a lot of IPA. The result has been better than expected and to my surprise, all tracks were still present:

KB_01.png KB_02.png

The minDIN6, once desoldered, also worked after lubrication and some hours of plugging/unplugging a male connector :rolleyes:

The internal cable signals are, following the PCB numbers:

1) FG (GND)
2) +5V
3) KB DATA
4) GND
5) KB CONNECTED (GND)

Detailed info of the keyboard connection signals can be found in the JX technical reference PDF. It served me well.

The cable between the keyboard and the main unit has been easier to get than expected, a simple male/male miniDIN6 (PS/2 shaped) worked flawlessly. Later I'll check the IR circuit, with a bit of luck I'll only need to replace the diodes as the keycode generation is working.

The RAM

Right after powering up with my newly repaired keyboard, the JX started to display an "ERROR A" and failing at 192KB. back to the workbench, checked all extended RAM card capacitors looking for a shorted one, nope, all good. Then after socketing two 41256 ICs and the second being faulty, plugged again the card and yep!, 384KB again!; but wait...isn't the card 8x41256 and 4x4464?, I've never noticed that it was a 384KB RAM upgrade to reach the max 512K supported by the JX!. So is it also failing to give me the full amount of RAM?, oh, come on...
Searching the web I wasn't able to found docs of the model (6454033B) ; but hey, I found a pic of a model close to mine and showed a jumper installed that I don't have. This is now my card:

EXRAM384.png

That's what it needed!, now the JX is checking the full 512KB:

JX_01.jpg
JX_02.jpg

Now I only need to create some boot disks the check both drives. None of my PCjr disks booted and none of my cartridges worked either (so I can conclude that they can be electrically compatible with the connector; but the software is not with the Japanese model), all of them displayed an "ERROR L", "Language" I guess...
 
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