Category: Old Hardware

I looked around a bit recently on what’s possible to do with the USB port of Nereid on X68000, and saw that the currently available drivers seem to be:

• Mouse
• Gamepad
• USB Floppy drive

… but I couldn’t find anyone that have written drivers for using USB memory sticks as hard drives.

I fucked around a bit with Claude and hey, now we have a driver that can do that.

Have been messing around with this quite a bit now and seems to work really well. Since the drive mounts as FAT16 instead of using binary images like BlueSCSI, it’s now extremely easy to transmit files between my computer and the X68000!

Since this is just something I shat out kindof quickly with a LLM, I can’t say I’m particularily proud of this thing, but it’s a weird new world we live in now when making these things is suddenly easy.

If I were to implement this myself, it would have taken me weeks/months of research to figure out how to approach it. Now I can just prompt some machine in the cloud and it spits out a surprisingly well written device driver for and old machine like this.

Things are getting weird.

I have a X68000 setup at my work desk which I only use for games, and I found it annoying to have to reach for the keyboard every time I wanted to launch a game through LHES.

My initial thinking was that I could create a custom game launcher which supported controllers, or modify LHES to have support for them. After thinking about it a bit, I realized that a better option would be making a utility for mapping joypad inputs as keyboard inputs.

I wasn’t initially sure if this was possible, but after some experimentation, this turned out really well!

It’s now available on github as x68k-joykey.

As an example, to use LHES as a launcher with the standard SCSI image that people are using (with !Start.bat scripts for launching games), you can run:

JOYKEY ENABLE -P1 -U=UP -D=DOWN -L=BS -R=CR -B=Q -P2 -C -A=OPT1 -B=ESC
LHES
JOYKEY DISABLE
IF EXIST !Start.bat !Start.bat

Player 1 controller is used for navigating into games (Double tap B to quit LHES and run !Start.bat). Player 2 controller is used to swap between HDD drives.

No changes are needed to AUTOEXEC.BAT/CONFIG.SYS. Just run the util to remap things.

Only tested with LHES, SWITCH and ED so far, but should work for a lot of stuff.

Note that since this relies on hooking things up to the VBLANK interrupt, apps/games which require ownership of this will NOT work.

A while back, I bought a cheap X68000 Compact that didn’t boot, and fixed it up well enough to be able to boot in 10Mhz mode, but not 16Mhz mode.

This involved both fixing issues with RAM accesses + bad logic IC’s related to audio. See earlier post here.

Considering it was bought broken and that repair took a lot of debugging, I was mostly happy with that outcome, but wanted to get back to fixing the 16Mhz mode too.

This summer, I finally went back to it and managed to fix it, so here’s a quick writeup.

Figuring out the crash

I started by probing the address lines of the X68000 until HALT was asserted, and noticed it crashed at the same spot as it did previously in 10Mhz mode before i fixed that mode.

It fails after a read of FF0636 which is a RTS instruction. The return address is incorrect, and things blow up.

Since that was what happened originally in 10Mhz mode, I could just assume that my previous fix was only _mostly_ correct.

Probing the RAM IC’s verified that only two of them were getting CS pulses in 16Mhz mode when LDS and UDS were asserted, while they all were in 10Mhz mode.

Looking back at the earlier “fix”

The previous fix I had for the RAM access was:

• IC84 Pin #13 -> IC84 Pin #4
• IC84 Pin #7 -> ASA Pin #3
• ASA Pin #3 lifted off pad

This was inspired by the schematics for the non-compact X68000 XVI (CZ-634C), since the schematics for compact was not available, and it appeared to be wired the same when inspecting signals.

Going back and reverting those fixes and probing things more carefully, I noticed that the compact does NOT have this exact wiring though.

When looking at UDS which were known to work, I can see that Pin#15 and Pin#6 are wired together, and continuity testing shows that this is also wired to the ASA UDS port.

On my machine, I could see that IC84 Pin #13 was NOT connected to Pin #4, which seemed weird, since I’d expect LDS to be have the same as UDS. Trace should be under IC, but assuming trace damage, the previous initial patch was correct.

What was wrong was the IC84 Pin #7 -> ASA Pin #3 part (which should be correct on the non-compact).

Simply reverting that fix, and cleaning up the bodge a bit made the machine boot in 16Mhz mode too.

Happy ending

Very glad to have this fixed. Machine now works 100%. Getting sidetracked a bit by messing up the wiring in the previous repair was awkward, but simply going back and probing things carefully made for a rather quick fix!

The best type of mistakes are ones that can be easily reverted.

Realized that I’m only using my X68030 and X68000 Compact right now, so putting away the rest of my X68000 in Storage until I need them for something.

All of these are bought broken and repaired. Ended up a fun stack of machines.

Fun pics below

Won an auction for this very rare peripheral for X68000 a while back.

This thing cost a massive 450,000yen at launch back in 1990, with each disk costing 30,000 additional yen… but they could hold 594MB of data, which was pretty insane back then, considering the X68000 HDD’s were more like 40MB.

It reads 5.25″ MO Disks, and they need to be 512 byte / sector with a total max size of 594MB (spread across two sides) to work. I tried some large MO disks and they did not work.

The ones sold with it back then were JY-701MPA, but I haven’t been able to trace down any of those.

The one’s I have that I managed to get working are Sony EDM-1DA1, but I’m sure other models would work too as long as having correct specs.

Setup

• Connect the device to a SCSI port on your machine. SASI devices will need a SCSI expansion card.
• Load a MO disk and power on machine and disk drive.
• Boot a Master Disc floppy
• Run

cd sxsi
scsiformat 

In SCSI format you want to do the following things:

• Initialize disk (5)
  • Don’t do the low level format, just initialize.
• Create a partition (2)
  • Use maximum available size
• If you want to boot from it: Make it bootable by going into Bootflags (4)
• Repeat for other side of Disk

It should look something like this when done:

Boot from it

To test booting from it, after making the partition bootable, I just copied the master disk contents to the MO disk with

A>COPYALL *.* C:

Then run SWITCH.X and set the machine to boot from SCSI ID 1. Works!

Unfortunately this thing has a vague fish smell from bad caps, so I need to go through and recap it now, which should be a fun project.

As I mentioned in the end of my earlier post about CZ-6EB1, a Japanese site mentioned that the 1991 October issue of I/O Magazine had info on building your own X68000 IO Expansion.

Tracking down that issue took me a few months, but I only managed to grab it along with a bunch of other issues, so now I have a lot of stuff to go through at some point.

Anyways, the Japanese site was correct and there definitely was some fun info in their. Looks like there’s actually a small prefix in the earlier issue as well though.

1991 September I/O Magazine

This magazine goes through a bunch of hardware for X68000 at a high level, and it has two pages with high level info on CZ-6EB1. This also mentions that the author has made their own expansion.

Info on that one is in the next issue and it’s… quite something.

1991 October I/O Magazine

This magazine shows a pretty impressive DIY build of a IO box. The cable spaghetti is… interesting.

It’s still a rad project though, and I kinda love that magazines used to publish these kinda projects.

The article is written by Masafumi Ichihara.

Just fucking look at this thing.

This is great, I love it.

I mean, don’t do this yourself maybe though.