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NEC PC-9801VX – SCSI Devices

So, I've gotten my PC-9801VX to power-on, boot a floppy disk and then initialise the 486 upgrade... the next step was to get a HDD attached. Luckily, the unit already came with both SASI and SCSI cards, so I just had to choose one and connect things. SCSI was chosen, as I don't even know what SASI is and, perfectly by chance, I'd purchased an external 4.3gb SCSI HDD with the matching HD50 plugs!

Upon searching the usual boxes'o'junk for a cable, I attempted to plug the unit in and, to my surprise, the connector on the SCSI card wasn't actually HD50.

Turns out it's a mini-centronics HPCN50! You can learn all about SCSI connectors over here. It seems this connector type is very popular amongst PC98s. With this new information, I went scouring the web for an adapter. I found one from my usual favourite seller in NSW (RetroShopBox on eBay) and then also another full SCSI cable (HPCN50 to HD50) from the UK... but that was to take a lot longer to arrive.

I adjusted the HDD to SCSI ID 0 and, with everything connected, booted the IPL disk and then MS-DOS 6.20 Disk #1. The installation was painless, thanks to the Gotek, and before long the machine rebooted and failed miserably. This was due to MS-DOS 6.20 trying to start without the 486 Accelerator initialised and so I rebooted and installed that via the Installation disk. Before long, the machine had rebooted into DOSSHELL!

Removable Media

I grabbed my nearest Magneto-Optical drive and chained it onto the SCSI bus. It happened to be set to ID 6 and I just left it as-is and attempted to boot. Before long it threw the following error:

No system files!

To add insult to injury, it just continued to emit a high pitched squeal. Seems it thinks/knows this is a removable drive and expects removable media to be bootable. The disk in there certainly wasn't... I didn't even know what was on it.

Just for fun, I slapped in the IPL disk, installed DOS, installed the accelerator and then voila!, the disk started booting.. But the fun didn't last long. It failed with an error initialising MSDOS.SYS? How does that even fail?

No matter of mucking around got me further... Until I switched the MO's SCSI ID from 6 to 1. I had no idea why, but on ID 1, the MO booted to a command prompt! Unfortunately, once booted, I couldn't get to the internal HDD. The MO was mounted as drive A: and the floppies were mounted straight afterwards. No HDDs to be seen.

I had initially expected this unit to show up as a second HDD, so was a little perplexed as to how to make it act as one. A few emails back and forth from Adachi-san saw me realise that I either had to configure the drive into HDD mode, or force the SCSI controller to treat it like a HDD.

The SCSI controller is a TEXA HA55-BSW and, whilst booting, there's an initialisation screen that shows the devices found on IDs. During this process, there's no hint that it's able to be configured. After a little bit of googling, it turns out it can be configured, but only if you hold down the T and S keys at the same time whilst it's initialising.

Inside the configuration menu, you'll find drive options in the second choice. From here you can tick through the IDs and set the parameters accordingly.

I happened to find that the drive type could be set to MO Small Image and, well, this worked! I now got to the SCSI boot menu instead of just booting directly from the MO.

From here I booted into DOS on the main HDD at SCSI ID 0, but I still could only see that HDD (and other partitions on that SCSI drive), and no other SCSI devices. After a few more emails, it turns out there's a requirement with PC98 SCSI IDs: they need to be consecutive! That explained the issue above with MSDOS.SYS, but not this new one. Adachi-san also passed me a formatter that could format 230mb MOs up to 218mb and I went for it. Actually, it was obvious that the format was wrong as this is how the MO showed in the SCSI boot menu:

Similar to USB keys of nowadays with multiple partitions, this MO has been partitioned+formatted in "removable mode" and therefore shows up corruptly in HD mode. I re-partitioned and re-formatted the drive in the current HD mode with (RMUTL (Now MOUTL) from Adachi-san, received 218mb free and drive C appeared! Yesssss...... We can now copy from MO to HDD.

Thanks to my MO USB drive on my main machine, I could start expanding HDI files onto MOs and tinker...

CD-ROMs

I thought I might have needed the latest CD Drivers from archive.org, but DOS 6.20 just installed NECCDB.SYS and MSCDEX.EXE and my SCSI CD drive was mounted! I could even list the contents of the CD in the drive! Looking more-closely, it's actually an NEC CD-3010A which is somehow covered by the driver installed. Note that upon installation, DOS copies the driver it wants to use to the DOS folder as NECCD.SYS. Just match the sizes to determine which one it's actually using.

The Final SCSI Stack

Somehow I had enough cables, with the correct SCSI connectors, to join all of these together and terminate them!

It all works perfectly and I'm actually really impressed with the tech-level of multiple-booting and boot-menu of my PC-9801VX.

NEC PC-9801VX – PK-X486 CPU Upgrade

So, this PC-9801VX came with the weird sticker on the front indicating that it was powered by a 486 CPU.

It was a pretty random claim seeing as that the base system is built from a 286. How could you possibly upgrade an 8-bit CPU to 32-bit?

A quick inspection (see the over here) saw that the 486 was contained on a daughter board which used a PLCC-socket adapter to hijack the 286 socket!

The upgrade happens to be an IO-DATA PK-X486/87SLS (IOD2Y284), consisting of a Texas Instruments TX486SLC 25mhz CPU coupled with a Cyrix FastMath CX-83387 33mhz 387 Math Coprocessor.

As that this CPU actually replaces the existing 286, it's always been active and operating the system but, regardless of this fact, the system still reports as a 286!

Trying to install DOS 6.20 very quickly throws a "You cannot install DOS 6.20 on a machine with a 286 Processor."

So, a little googling later and it turns out there's a TSR which needs to be loaded. That link indicates the TSR is named PK486.COM, but no amount of googling resulted in such a file. Instead, PK486D.COM showed better results, like this Interrupt Extender for this CPU Upgrade, but that software still didn't include the TSR!

Finally, a little more googling brought up this Japanese forum post indicating that there was an old oldsoft/98.htm page at the IODATA website that had derelique drivers. Of course, this page no longer existed, so web.archive.org to the rescue! Finally, there it is, down the bottom of the page.

Unfortunately, the files are just upgrades and want the original setup disk to hack some bytes. So, next up I started clicking random links on the iodata library site and found this page. It's full of random Win95 stuff, but one file seemed to be valid for a newer upgrade card than I had.

The COM files looked great... so I just renamed and executed... and the CPUCHK.COM even threw out the following result...

But, alas, both TSRs just reported an incorrect CPU when trying to run. Of course, what are the chances they'd even work.

UPDATE:: Adachi-san of Adachi Giken has come to the rescue! You can skip this part.

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IF ANYONE HAS ONE OF THESE UPGRADE KITS, CAN THEY PLEASE MAKE AN IMAGE OF THE DISKS FOR THE INTERNET?... there's many sites with people asking for the software and I'd love to try it out! The box looks like this... and the disks seem to come in both 5.25 and 3.5" variants.

The disks are labelled "共通サポートソフト".

Excuse the image quality... they were flogged from a yahoo auction. But here's a better close-up...

I'll have to keep watching the auctions as those Power Up Kit /PK-X486Sシリーズ disks above went for $10.

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The disks!

So, the kit comes with two disks: an IPL and an Installation disk.

Downloads
	IPL Disk Image		Installation Disk Image

The IPL (or Initial Program Loader) is used to boot the machine into a state where the seconday CPU is active. This is good to use prior to installation of something that needs a 386+ (i.e. DOS 6.20), so boot this disk to the following prompt:

And then swap disks. Once done, hit enter and you'll get to continue as if you booted the second disk you inserted, but on a 486! Of course, after installation, rebooting the machine will set the 286 active again and that's where the Installation disk comes in. Let the machine restart after installing DOS 6.20 and watch it crash and burn. Once it does that, insert the Installation disk and restart the machine...

That screen above scrolls onto the screen in 90s goodness... and then you get the main menu. The options are to Backup something, read the README, install the software or configure cache. Choose the third option, and then your SCSI disk.

From here, choose the partition/installation and go for it!

You'll then be told that everything is complete and that it's time to restart your machine.

With this done, your machine is now a 486! Congrats. Message me if you need the disk images.