PC-9801 UV - some questions...

Started by Dr.Wily, September 16, 2015, 10:47:33 PM

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Hello !
I have a PC-98 UV, it seems to be working but I don't have any boot disk to confirm if it can load floppies... so, before that I have some questions

- Is there a setup BIOS like or something other than dip switches in front of the case ?

- is the drives support 720kb floppies ?

- how I can extend ram ? I notice there are some UV models with 640ko and others with 384. But I never seen any RAM extention slot on motherboard .

- without HDD, which is the best method to format and boot floppies ?

Thanks !


Simm's Club - French LAN Gaming (PC & Consoles) : http://www.asso-sc.com


Hi Dr. Wily,

Nice to meet you and welcome to the PC-98 hardware scene!

I saw your post here and then went over to the Assembler Games thread that offers a guide for writing PC-98 disk images to real floppy disks and saw that you already discovered that thread.
I'm not at all familiar with the PC-9801 UV, but from what I can see from an information sheet it looks like it has 2 x 3.5 FDD drives, an expansion bay for something below the drives, and it's equipped with a HDD as well which is arguably the most important part if you want to have the most fun with your computer.

Hopefully we can troubleshoot your error with writing disk images and I'm pretty sure I have a Dos 6.2 image that was all ready to be written to the disk  in the format required for that guide, but I haven't written actual disks in quite some time, so I'm a bit rusty on the process. I just remember the guide worked for me and my friend Xalphenos using USB - 3-Mode FDDs hooked to a 32-bit Windows setup.

But all that aside, unless you are just extremely curious about writing your own disks to actual floppies, I would say to focus your efforts on getting your HDD up and running with Dos 6.2 or Windows, depending on if you want to run Windows on it. I pretty much use Dos 6.2 and Dos 3.3 exclusively for my PC-98 hobbies so far. Yes,  you might be saying to yourself, "Well duh, that's what I want to do. I want to install Dos / Windows onto a HDD," but there is an easier solution. In some of the threads here, you'll notice that there is a community image (currently version 1.5) with some games loaded into Dos 6.2, and another image called YAHDI which (currently) has less games installed, but a lot more features that are ready to go. Another member here named Caius, and I are working on creating a new YADHI image (couple of them actually) that come with a lot more games and software installed.

The nice thing about these images is that Dos 6.2 is already installed and ready to go and if you write it to a CF card and use a IDE to CF card adapter, for your HDD inside of the PC-98, you can then easily write new files to it by inserting the CF card into a reader connected to your PC. The goal of the image that we are working on is to present more or less a Best Collection of PC-98 software that can be run from the HDD alone. But of course, not all software can be run this way and some will be disk only, so that will come full circle back to your original problem.

Not sure if you've already looked into this before, but there is a HxC Floppy Disk Emulator that supports .d88 files, which can be either PC-88 or PC-98 software once it is converted using a special HxC program to turn it into a format that the HxC emulator will understand. I do not have one of these HxC devices yet, but I definitely plan to either get one of these or try to figure out a cheaper solution using a different FDD emulator called a Gotek. Goteks are generally a third of the price of a HxC, however they have not really been compatible with as many formats like the HxC has been. That has changed somewhat with Jeff from the HxC group providing a bootloader license for the HxC firmware to be installed onto a Gotek for 10 Euro and a special device that will be needed to program it. If this works out, this would be yet another alternative for replacing our mechanical FDD drives with ones that we can insert a USB stick filled with disk images into.

Not sure about the RAM, but some models have an actual RAM module that can be installed depending on the computer, I believe RAM can also be upgraded via a C-Bus card.



Thanks SkyeWelse ;)
I managed to format floppy disk and boot with DOS 3.3r... after long experiments. But this is good !

First, PC-98 is a straight forward machine compare to classic western PC at the same time. FM sound out of the box, good video rendering and hardware stability. And the best for me, a bunch of esoterics C-BUS devices ! i notice that PC-98 was used also in US and european market for industry. Specificaly on EDM machines and continue to be used today.

The PC-9801 model you listed here is not totaly the same as mine. My PC-98 is not the "11" version of PC-9801 UV. It has only 384kb of RAM and no hard disk. Only 2HD 3'5'' floppy drives as boot devices. To format floppies at 1.23mb I tested many drives on many OS. Most drives I have tested don't support 3 mode natively. Even the famous Samsung sfd-321b.

Plus, Win7 don't support 1.23Mb. It has able to read it with a proper couple of floppy drive / FDC controler but can't format. When you try to format with "format x: /a:1024 /t:77 /n:8", Win7 returns "parameters not supported". This is the result with an Sony USB drive PCGA-UF5D hooked on Win7.Fortunately, Win2k and XP are able to format at 1.23mb... but Vector's Diskimage fails to write data properly on disk under 2k/XP.

To make a readable disk, I dug up a old Toshiba laptop in my attic. This computer is a Satellite 220CS with 16mb of RAM. It also equipped with a floppy drive. A Teac fd-05hg who support 3 mode natively (without mod)... but to read and write at 1.23mb, the BIOS must support 3 mode too. The Toshiba Satellite 220cs BIOS don't provide any 3 mode option in his BIOS. It does not mean that it not support 3 mode... I must install an OS to test.

Can't install Win2k with only 16mb of RAM. Go for Win98, the japanese version who, luckily, provide 3 mode driver for Toshiba laptop (change the default Windows driver both on drive and controler). And... voilĂ  ! The drive can read 1.23mb floppies (tested with PC-FXGA setup floppy)... but urgh can't format it. Go for testing Vector's Diskimage... and it write flawlessly HDM disk images... and PC-98 boot up.

In a nutshell :

- find a 3 mode USB drive : Sony PCGA-UF5D and Teac fd-05hg (only "HG" version) are certified to work and support 360rpm read and write. In the case of Teac fd-05hg, packaged in USB you must care of the controler. I have a Teac drive with USB enclosure, his USB controler is a Mitsumi who don't support 3 mode. Don't forget the drive AND the controler must support 3 mode.

- alternatively you can get a slim drive like Teac fd-05hg and use an adapter to hook the slim floppy drive to your motherboard FCD. The JM215a adapter. Don't forget to enable 3 mode in your BIOS.
- Use Win XP or 2k to format a 3'5'' floppy at 1.23mb. The command 'format a: /a:1024 /t:77 /n:8 /u" works.

- To me, drive image from Vector's website was not able to write HDM images under XP/2K. If it is your case, use a copy of Windows 98 on a real machine (an old one if you can). If your plan is to install Win 98 on the same machine as your main OS, be careful, win98 does not works when you have over 4Gb of RAM (it complaining about insufficient memory !! ::) ). Keep only 512 or 1Gb of RAM before setup Win98.

- After setup, install 3 mode driver (most of the 3 mode drivers are based on the same files). Test if the previous formated floppy is readable by the OS.

- If it's the case, use Drivemage to write PC-98 software on the floppy.
At this time, I was able to boot DOS 3.3r, DOS 6.2 and play at Popful Mail (great BGM in this game). Next, use PC-FXGa... but I need a SCSI card...

On next post I provide all sources and photos. I also a question about a strange C-Bus board that I can't indentify.

See you  ;)


Simm's Club - French LAN Gaming (PC & Consoles) : http://www.asso-sc.com