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20Oct/220

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.

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14Oct/220

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.


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.


The disks!

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

Filed under: Retro No Comments
28Apr/220

Z Scale Layout – Akia 485-Series Traction Tyres

Just for a lesson in complete-failure, I attempted the fitting of traction tyres to an Akia 485-series EMU powered-car. The train couldn't get up gradients and so I thought I'd see how it went with traction tyres from Rokuhan.

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Rokuhan provides both 4mm and 5mm tyres, and I purchased a bunch of both sizes as I know I'll need them in the future. The power car in question is a standard 485-series passenger car and the shell comes off once minimal force is applied to separate both walls from the chassis. From here, you then need to remove the top circuit board by inserting a flat-head screwdriver in the 4 holes in the chassis, two on each side.

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Once that's off, remove the two weights.

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It gets a little tricky from here. The bogies are attached via drive-shafts with lateral pins. The chassis is a single unit, so you actually have to spread the frame to get the bogies out. Make sure to allow space for the drive-shafts when doing this, otherwise you might snap them.

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With the bogies out, you can grab a flat-head screwdriver and press down on the clips next to the power pick-ups. Pushing down on these will push the under-frame of the bogie onto the table. Once it's separated enough, you can flip the bogie over and lever the frame off.

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With this finally off, you have full access to the wheelsets and you can install traction tyres.

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Unfortunately, these wheelsets don't have the grooves for tyres and the trains run erratically once installed.
So don't do it! The end.

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5Mar/220

DataStor Commuter Parallel Port IDE HDD

This came in a bulk eBay purchase months back but I only just re-discovered in a box today. I love surprises! I've recently been going through all the boxes'o'shite and so I'm sure there'll be more surprised to document.

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It came in a pleather pouch with a manual, floppies and all required cables. Below you can see the DC power adapters actually piggy-back onto either an AT Keyboard socket or a PS/2 port. Very handy! I am still trying to work out if plugging my mouse into the piggy-back pushed pins inside my mouse's plug, or if it was just ready to break. Either way, had to fix that also.

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The unit actually allows the printer port to pass through, but I didn't test this. I might grab a parallel port Zip Drive and see if you can daisy chain them. Otherwise I assume you can put a printer on the end.

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As for operations, the floppies included had expired, so I downloaded the driver package for Windows/NT/OS2/DOS and created a bootable floppy disk image with the required DOS tools. The main driver is CDISK.SYS and this just needs a standard DEVICE line in CONFIG.SYS with no arguments. It's all on the floppy image above.

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With the floppy in the drive, the disk came straight up and prompted me to partition/format it. It saw a 3.2gb HDD inside and told me to make two separate partitions of 2048mb and 1248mb, as the OS doesn't support disks bigger than 2gb! Ah, history.

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13Jan/220

Handy Portable Ethernet Pocket Adapter

Aaand another impulse purchase from eBay: a Handy Portable Ethernet Pocket Adapter. What a name? Turns out this is a clone of the Accton EN2209. Finding software wasn't the easiest, but somehow a university in Taiwan had the required file.

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Installation on a 486

My IBM PS/1 486 received this unit (after a WFW311 upgrade) and worked perfectly with it. Installation was very straight forward! Just download TCP/IP for WFW and install it as an additional protocol. DHCP worked fine.

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Installation on a PIII-500mhz

Things got awry from here. Firstly, running WFW311 on a PIII-500 with 512mb RAM is probably not a recommended thing to do... but... it installed so quickly... it was lovely. The adapter drivers installed and came up on a reboot. As soon as TCP/IP was installed, the whole machine froze!

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That second transmission light just stayed locked on and the whole machine actually became non-responsive. Seems to be some kind of race condition with the device... so... what to do? After thinking it was Parallel port settings, I changed them all to no avail. I then guessed it was clock speed, so I down-graded the 500mhz to the slowest setting possible: 333mhz.

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At 333mhz, the unit worked perfectly! WFW311 on this hardware is lovely! :) I then upgraded to 375mhz (75mhz bus), but it was NOT stable. WFW311 would lock every-other-time when booting? Seems 333mhz is the magic number.

What about Linux?

I started digging around for a Linux driver and found a few hits on the parport mailing list. These then lead me to harshman's archived page containing a driver! Seems it needs Kernel 2.0.30, so I went back to le'googs and started hunting.

Since I love Red Hat Linux so much, I jumped over to their page and checked the version history. Nice, we have a matched kernel with Red Hat Linux Version 4.2! Back to the Red Hat Linux Archive and there's a 4.2 folder... but wait, there's no ISO in the expected folder? Fortunately, the main guts of the OS are still available and we can then make our own installation media. Download that folder and copy it ALL onto a blank CD. Then jump into the images folder and write boot.img to a floppy. Special thanks to grem75 in this reddit thread for pointing out the required steps.

But that actually didn't work... No matter what I copied over, the installer baulked with an unrecognised Red Hat CD. So, I then downloaded the ISOs from archive.org. I'm surprised that didn't come up as a first search result, but then it occurred to me that archive.org never does? Has it blocked google?

Meanwhile, no amount of burning that image under Windows would work! I even tried to boot up an old ThinkPad with Linux Mint and wodim to try and get it to burn successfully. It didn't... it seems there's an issue with those images on archive.org? Finally, I used the FTP method and an NE2000 compatible card I had lying around to install RedHat.

Once RedHat 4.2 was up, I followed the instructions on harshman's page and, after a first failed insmod, the unit came up on the second attempt, received an IP and I was able to ftp into redhat! Amazing! This was also on the 500mhz at 100% speed, so no race conditions here!

Finally, if you check harshman's page, you'll note that he notes that there's already an updated version whilst he was making his... I wonder if a newer version of RedHat will support this unit?

Filed under: Retro No Comments
11Jan/221

Covox Voice Master Key

This item came up on eBay a long time back and went straight into the 'projects' box. Thanks to a newfound push to clean up the spare room, that box has been turned upside-down and dealt with. So, without any further ado, I present to you a 1988-vintage COVOX Voice Master Key.

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The box was well-worn, but all text can be read. Of interest is, in the second-last paragraph, the redacting of the quote "Plays back through optional COVOX Speech Thing". Was the redaction done by a child with a marker? Or from the factory? Finding information on this card online is pretty difficult. First hit was this Korean blog post on naver.com and you'll notice that the redacted sentence is totally removed from their version of the product. Their version seems to be a lot newer, but only of box design, not product name or quality.

Nerdly Pleasures also has a post on COVOX devices, but was very light-on for info on this card. I hope I can help them with their photo of the card as well. Also, the I/O for the DAC can be gleaned from the jumper setting above.

So what does it do?

First and foremost, this is one of the first pieces of hardware to let you control an IBM PC via voice. If I had the software, I'd test this functionality out... unfortunately I don't and no amount of searching has dredged up the installation disks. There's a disk image listing here, but no actual disk image? I messaged the author of that post and he just silently stepped out of the conversation... he must have the actual image to take those screenshots from DOSBOX? I then started by own thread, but no one cares.

A little more digging brought up this request post on Amibay for the same software. I posted a bump reply and got in trouble for hijacking someone else's thread... didn't realise that was a rule. I then PM'd the author, but no response as of yet.

So, without any software, I can't do the voice recognition/control stuffs... but can it play audio?

Audio output hardware

This unit does have an output port and the included head-set is just that; a speaker and a microphone! There are two microphone ports on the card, but we don't actually care about them as we don't have any software that'll make use of them. The headphone port interests me though as, with the redacted text on the box, there must be some way to use the 'included' COVOX Speech Thing functionality. The directory listing of the installation disk above even has a THING.EXE which must enable this card as a sound output device.

The output circuit includes an LM386N amplifier that's fed from the resistor bridge. That bridge is fed directly from the ISA bus data lines, so it must do something if data is fed in. The I/O Address jumper selections allow settings from 0x22f through to 0x28f. I initially thought that was 0x0220, thinking the F was just some naming style, and, after taking out my SB16, tried to get my machine to output sound via FT2 on 0x220... this was entirely fruitless and entirely wrong! I mean, come on, the jumpers don't lie... the I/O ranges really are all based with an 'f' on the end!

So, what to do? First up, anything that wants to use a COVOX Speech Thing as a sound output device will expect it to be on LPT1 or LPT2. These ports are configured via your BIOS and, well, it just wont work adjusting BIOS settings as anything configured there will just send data out the existing configured printer port. I went googling around and found that people had built their own DACs back in the day and someone even has a project for a DAC that sits in an ISA slot known as ISA-DAC-r0. Further on from that, I then found instructions on how to use it on the DOS Re-loaded forum.

There's a really interesting screenshot half-way down that forum topic where the user has used the DOS debug command to hack a memory address. This address contains the I/O register of your machine's LPT ports. Hilariously, you can actually tweak these addresses live when your machine is running!? The basic idea is to type debug, hit enter, then type the following:

-e 40:08 78 03 2f 02

then press enter and then type q and enter to quit. Above, you've entered the bytes 78 03 2f 02 into memory address 40:08. It turns out that that memory address is the system configuration area for the IO base address for your LPT ports and you can chain as many as you want together to pretend you have LPT ports. In the case above, the first port is 0x378, written as high-byte low-byte and then 0x22f, again as high-byte low-byte. Entering the command above will configure your DOS session to have LPT1:0x378 and LPT2:0x22F. Does it work? I configured Fast Tracker II to have a SoundPlayer on LPT2...

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And...

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Actually... here's a proper demo of its capabilities:

Woah! The audio quality was as-good-as any original SB2.0 that I remember... but it's probably worse... and MONO. Seems can you have two DACS and have FT2 run LPT1+LPT2 for stereo sound. More games were downloaded and tested and all worked fine! Amazing.

Now to just find the actual software!

Filed under: Retro 1 Comment
6Dec/210

NEC PC-9801VX – Video Output

After getting the PC-9801VX up and running via the monochrome output, it was time to get the RGB signals properly-connected to a real monitor. Thanks to previously playing with Amigas, I actually have an LCD on-hand that can do 15khz via a standard VGA cable. What to do? Hack together a cable that would interface with the DB-15 port on the PC-9801.

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As mentioned, this unit uses a DB-15 Analog port which looks exactly like a Macintosh Video port. Of course, it's not, so you can't just use a Mac adapter, but you can refit one, thanks to this blog. You can also just roll-your-own-cable, using the pinout here. Jaycar has the necessary DB-15 male port with housing and the cable above was built.

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Plugging it in saw the picture work beautifully... but the fonts were still out. A-Train was also still scaling off the bottom edge?

Front-Panel Dip-Switches

Turns out there's display configuration options on the front-panel to configure resolutions and font-sizes. As seen above, the DOS installation screen looked OK for the most part, but the selectable menu options showed stretched/cut-off fonts!? A quick read of the the dipswitch descriptions pointed to items that may help.

SW1-1 sets the output resolution from 640x200 to 640x400 and this helped a bit, but the fonts were still wrong. I then also toggled SW2-3 and SW2-4 to enable both 80-character screen width and 25-character screen height. After this? Perrrrrfect!

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Very similar to the version from the MSX.

You don't have a 15khz monitor?

No fret! This is the internet and someone has already done this before. To make this work, you'll need a GBS8200 video adapter. Once you have this in-hand, you'll need to either wire things in directly, or build a circuit such as antarcticlion's GBHV_RGBS_CONV adapter. I've had a few PCBs printed for me...

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... and I intend to build them up and test them. If anyone wants one, then contact me here. I'll post again once I've built one and got it going.

Filed under: Retro No Comments
29Nov/210

NEC PC-9801VX – Floppy Drive Maintenance

If you have the opportunity, do NOT use floppy disks... for anything... ever. I've just spent a lot of time debugging issues when I should've been playing A-Train! Due to the effort I've spent, I hope the answers you find in the rant below help you and prevent such effort expenditure. The goal was simple: The PC-9801VX was up and running and I wanted to run this...

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Yes, it's another version of A-Train. It's version 2, still prior to the version 3 that was released internationally. Now that I think of it, I'd actually purchased this game with a bunch of trains back here! I'd done nothing with it since... but now finally had a machine to run it on.

Unfortunately, the drives wouldn't even accept floppies!

I can't insert a floppy disk!

When this unit arrived, I tried to insert A-Train Disk A into Drive A. The disk would slide 70% in and then hit something. I decided not to push my luck and opened everything up...

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If you've noticed too much copper in the photo above, then you'd be spot-on. The 'head cover' of the read head has popped off (presumably in transit) and sat itself in front of the read head. This has succesfully blocked the floppy disk from inserting all the way. As these machines are super-popular in Japan, a quick Google found many examples of people having the same issue. I opened up the second drive and found the same issue!

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Each site that mentioned this issue had a different solution! Leave the cover on, take it off... leave it on? take it off? I'll do the latter... for now.

Expired capacitors

Now that the floppies could enter the drives, I tried to boot the machine. Drive A would do nothing... it'd just pretend there was no floppy at all. Drive B got as far as below and then noisily failed. The failure let me believe that it'd at-least loaded a bit of data from the disk.

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So, what to do? Fix Drive A first, then work out if it could do better than Drive B. I've already hinted to the issue, but it all became very obvious after extracting Drive A and flipping it over:

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What a mess! A quick google around found this article on FD1155D maintenance and, to my surprise, it actually mentions how to fix this exact problem. It mentions that if the disk isn't found and the motor just spins (which it did), then these capcitors are to blame. After a quick bit of cleaning and soldering, the tracks actually proved to still be conductive. I added a jumper wire anyway and replaced the capacitors as required.

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Shit job, I know, but.. it worked! Drive A now produced the SAME ERROR as Drive B! Progress!? Based on process-of-elimination, if both drives produce the same error, it's no longer the drives at fault. It's the motherboard (in-built controller) or the floppy disk!

Making my own floppies

First things first: make sure you have an old PC with a known-working 5 1/4" drive. Don't even bother going down this route if you have suspicions about the PC side of things. I went around in a few circles at the start as my floppy drive half-read the first disk I put in, only to totally reject everything after. The fix? Clean the heads with an ear-bud (q-tip?) and isopropyl alcohol! After that, it worked like a dream.

With the floppy drive functional, and Win98 Japanese version installed, I could then use the tools to get floppies written. I followed the instructions here and downloaded both Virtual Floppy Image Converter and Disk Copy Utility. Aim for the green download buttons on the pages when you're trying to obtain the software.

From here, everything was extracted and a relevant DOS bootdisk was found from the PC-98 Software Dump archive over at archive.org. There's also a bigger archive here, for those interested. The DOS disk image was inside the OS folder in FDI format, so it needed to be converted first. Go to the Virtual Floppy Image Converter folder and double-click the exe.

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Choose English and then set the default output location.

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Finally drop the FDI image onto the app and a DCU file will be spat out. With a blank/spare floppy disk in the 5 1/4" floppy drive, open a DOS prompt and browse to the folder where the DCU image file is. Alternatively you can browse to the DCU application folder and just edit the command line below to find the DCU image file.

c:\DCU\DCU.exe -f @C:\PC-98\A.DCU,0

Above, correct the path for DCU and the path and filename for your DCU floppy image. The -f means format the sector prior to writing and the ,0 means write to Drive 0. This is A:, with Drive 1 being B. This software also runs on the PC-98 where the drives are 1,2,3,4 and not A,B,etc...

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I tested writing the DOS 3.3 disk to a blank floppy first. It ran quickly and worked flawlessly .. My PC-9801VX booted this newly-written disk to an installer! No hard-drives on this unit yet, but this made me pretty darn happy! I then decided to try and re-write the A-Train Disk A. It was already broken, so why not just try and re-write the same image back to it. The disk image is actually in the same archive above, so I extracted it, converted it and tried to write it...

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I first tried to write the DCU file to a blank disk and this completed with no issues, so I put it to the side. I then tried repeatedly to write the image back to the actual A-Train floppy, after removing the copy-protect tape. It kicked off and threw me to an input prompt very quickly. This prompt, as shown above along the bottom line, gives you a few options when DCU hits an error: R for retry, F for re-format and then retry and I for ignore-and-continue. Of course, choosing the latter will leave holes in your written image. As I'd mentioned, and as seen above, the errors weren't always perfectly aligned, but they were not stopping, so yeah, unfortunately that disk was trashed. I wondered if it could be cleaned (Herb Johnson has some tips)? Or if it's totally scratched up... or if you can even replace the medium inside? I tried a bit of isopropyl on it, as I'd done with the drive heads, but it didn't many any huge difference.

Just for fun, I thought I'd test the A-Train Disk A that I'd written to a blank disk. It booted fine, and that's when I realised I had options: leave the 'backup' disk in the box and don't touch the original?, try and transfer outer disk labels?, try and transfer inner disk guts? Hmmmm....

Re-sleeving or Re-mediuming a 5 1/4" Floppy Disk

This was super-risky. I had a properly-copied version of disk A on a (lol) Microsoft Works disk.. and a dead original disk. What to do? Pry open the original and swap the medium. First? Get out your Swiss Army Knife and perform surgery...

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Once you have the top broken open, do the same with the donor disk... being super-careful the whole time and remember: DON'T TOUCH THE MEDIUM.

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Looking at the old medium, you can see why it was never going to work (and also really hard to photograph):

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With everything out, just slot the new medium into the old sleeve and apply a TINY bit of glue along the seam you previously split open. And then?... test...

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Shit photos, I know... the game also seems to have shifted into a new resolution/mode and it's interlaced itself off the screen. Whilst my SCSI adapters are in-transit, I'll have to work out a proper video solution. (Update: Learn all about how to get proper video output here.

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25Nov/212

NEC PC-9801VX – Tear-down

I've always been fascinated by the older Japanese beige desktops and couldn't resist another impulse-buy when I saw this PC-9801VX show up on eBay. It was cheap, as it was listed as junk, until the shipping cost doubled the price. Regardless, I took the gamble, as I have a copy of A-Train for the PC-98 that needs a home.

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It arrived quickly, as postage from Japan can only currently be done via expensive couriers. Before long it was plugged into the step-down converter and failed to do anything good. From what I understand, on power up these machines are meant to PI-PO from their internal speakers... Of which this one did not!

A quick tear down saw the cause... but more on that later. What was I thinking?; purchasing such a huge beige boxen of junk. Fortunately, the tear down also saw that it came with surprises! The list included: a 4MB o'RAM CBUS board, an 8MB o'RAM CBUS board, a SCSI CBUS board and a SASI CBUS board. Also, two 5 1/2" floppy drives which can't be scoffed at... if they work.

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After a lot of research, it turns out that this unit is actually a 286, when purchased new. There's a lot of information online, but most of it is in Japanese. Fortunately, Wikipedia has a great article on the PC-98 series of machines and, if you scroll down far enough, you'll see this unit listed as an 80286 @ 8 or 10 MHz. BUT! What's that random sticker on the front?

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A 486, you say? In a 286 motherboard? I didn't quite believe it when I saw the photos on the auction... but opening it up showed that there was a slot for CPU upgrades and, well yes, you can actually put a myriad of faster CPUs in there! This one just happened to have a 486 upgrade.

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Nice. This opens up the game-play and MS Windows opportunities... if only I can get it to run.

Why wouldn't it boot?

Unfortunately, once down to the board, the CMOS battery proved to be the cause of failing to post. Excuse the awful photo, but I was in a state of buyer's remorse...

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You can see the green.. all the way into the CPU slot (middle-bottom) and, well, even further off the edges of the photo. The battery was quickly removed, but the damage was far-spread. Without schematics, tracing those corroded lines would be a nightmare. But what if I could find a replacement?

Buyee to the rescue

Turns out I had a cart of things to purchase from Japan, so I bit the bullet and purchased a junk spare motherboard for this machine. Yes, junk! That's all that was available online... no one in their right-mind would list these boards as 100% brand-new and ready-to-roll. I threw in a LAN card and a terribly-yellowed keyboard, just to double-down on my losses if everything failed! These also arrived in quick succession as Buyee charges like a wounded bull for shipping and uses top-notch couriers.

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The board was inspected and, to my surprise, was somehow perfectly clean. As above, you can see that the battery had corrosion, but it hadn't spread! Compared to the other board, it was a beautiful site.

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Shit photo, I agree... but above you can see the difference of the areas under the battery. Top being the newly-acquired board, bottom being the one I may have half-attacked with isopropyl and a toothbrush. Maybe, now that I have a working board, I can trace everything on it and check on the old... but honeslty, even in 1986 these boards were so bloody complex that I don't believe I have the skills to re-trace all of those traces.

But does it work?

Everything was assembled hastily... First flick of the switch, nothing... crickets. After a re-seat of everything that could be re-seated, I flicked it again. During the re-seating, I'd also turned the front volume dial up to MAXXX and, on pressing the power a seriously neighbour-annoying PIIIII-POOO PAAAAAAAAAAAAAA was emitted... Of course, the glee of the first two notes was murdered when that last note came out, deafening and disturbing, lasting until I hit the power switch.

Third flick, after another re-seat... PI-PO! Shit, that sounded perfect... I just had nothing plugged in to any video outputs.

Making it output video

This vintage beast loves its archaic refresh rates (more info here). RGB is 15khz or possibly 24khz, but nothing a new monitor will approve of. This video card has three output ports and you'll find the pin-outs here. I hacked together a 5-pin DIN to RCA plug cable (same as the Megadrive, actually, just without sound) and hooked it from the video card's top Mono output port to my 4:3 Samsung LCD.

It worked! But the picture wasn't great... maybe this is NTSC? Probably. I re-installed my capture card and tested out VLC with correct NTSC_J settings.

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It @#$%#$$# works! That last shot is with the SCSI card in... so it's found the TEXACO BIOS (is that the oil company? where did this machine come from?!) and tried to enumerate SCSI devices. I had none for it... so I removed ALL CBUS cards and tried to boot my A-Train floppy...

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First drive found nothing, and when nothing is found the machine just boots into the BASIC prompt. After a reboot with the floppy in drive B, it produced the above and stalled. It actually sounded pretty bad... but diagnosing the floppy drives is a whole-nother post, of which I'll tackle later.

In the meantime, if you want to know more about these machines, check out NEC PC98 Basic Reference. The amount of information in there is amazing!

(Update: The floppy drives live!)

Filed under: Retro 2 Comments
10Sep/210

HoneyBee Mega Drive Controller Directions At 45°?

I've been fixing a bulk load of SMS/SMS2/MegaDrive stuff and one of these controllers was thrown in with a note stating "Erratic Directions."

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Externally everything checked out, so I opened it up and continuity-tested the cable and plug. No issues there! I tested it again on the SMS2 that I had available and realised that I could get the directions I wanted by mashing in the corners of the D-PAD... what gives? I opened it right up...

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What's going on here? The actual D-PAD circuit board contacts aren't in an NESW orientation? They're a box, flat on the ground? I continuity-tested for the UP button and it turns out to be the top-right pad. Just to confirm I wasn't bonkers, I put the rubber-contact-thingy back in the D-PAD housing and sure-enough, the pads match the pads!

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So wait, to get the direction I want, I REALLY DO have to mash in the corners of the D-PAD. This is BY DESIGN. I wasn't a very good gamer when I was young, and this system was available to me at that time. The range is Competition Pro, so I assume this was an answer to the kiddies who held the controller at 45-deg in their left hand and mashed the other buttons with their right? Google is giving me nothing.

NOTE: just looking at that first picture, you can see where your thumb is meant to rest. This easily hints at where UP is. Can someone please point me to documentation where this is made clear that the directions are 45-deg clockwise rotated?

Filed under: Retro No Comments