Tag: x68000

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.

Have been looking for one of these for a while, and finally managed to buy one for a mostly OK price. Here is a writeup on these things since there’s not that much available online.

High level features

CZ-6EB1 expands a two-slot X68000 into a four-slot computer, by plugging in an expansion card into the X68000 which routes two flat cables to a breakout box containing four IO slots. This likely works similar to how it’s done in a X68000 Pro.

This box has a separate PSU for the four cards, since powering the cards over the flat cable would not be feasible. This PSU will only power the card when power from the host machine is detected, otherwise the device stands in “standby” mode.

I bought a photocopied manual for these in a separate auction, which I’ve scanned and made available here.

Internals

The IO breakout board which plus into the host machine has only two connectors wired to the edge connectors. There’s no other circuitry on these.

These plug into the main board of the CZ-6EB1, which is called K5414DE. This board has a section near the flat-cable connectors which seems responsible for switching the power to the I/O cards on/off. There are two CK2605 PLD’s at IC1 and IC2, which I should probe with a logic analyzer and dump at some point.

I suspect the IC2 is responsible for the power management, while IC1 handles IRQ/ACK signals across the four slots somehow similar to how it works on the X68000 Pro.

There’s nothing particularly interesting about the PSU. There’s quite a lot of glue on some of the caps which makes recapping awkward but doable.

Recapping / cap-list

I decided to recap this thing, and found some sketchy looking caps which had started to leak so that was a good idea. The full cap-list is below. Something mostly similar in size will work, since there’s a lot of space available.

PSU

Main board

Hooking things up

Getting things working on a regular 10Mhz X68000 is quite simple.

• Plug the card into Slot 2 of the X68000 and mount the back cover
• Connect the FG terminals on the X68000 to the CZ-6EB1
• Insert expansion cards into CZ-6EB1
• Power on the CZ-6EB1. It should have a red LED indicating standby
• Power on the X68000, the CZ-6EB1 will wake up as well.

RAM incompatibilities

When connected to a CZ-600, I could plug either a XSIMM10 or a Etarikashikoshi into the expansion unit, and have them be detected and work properly when running Memtest. Using a Nereid as RAM expansion did however NOT work, and kept giving me memtest errors. It works fine without the expansion box, so something was weird there.

With a X68030, I was unable to get any RAM card to work through the expansion box. The memory gets detected, but memtest shows failures, and games will not run well.

The manual only states that CZ-600 (10Mhz) is supported, and I could definitely see the higher clock rate causing these issues somehow.

Using other I/O cards like MIDI did work with this when connected to a X68030, but since the manual states that the internal Slot 1 cannot be used when the CZ-600 is hooked up, this limits the system to the internal 4MB RAM. Maybe that can be worked around somehow. Not sure.

Should you buy one / Other options?

Buying one of these is only really worth it for the “cool factor”, since it looks awesome next to a X68000. It being limited to 10Mhz for RAM means that the more sane option for having four slots is just to buy a X68000 Pro, which will cost less than just the expansion box.

Another four slot option is “Xpander IV” which extends the XVI Model with an internal four slot expansion. This looks real cool, but was not an official product and seems extremely rare. See: https://akiba-pc.watch.impress.co.jp/docs/wakiba/find/745817.html

Potential future projects

I haven’t seen any real documentation on how the conversion from two to four slots actually works. There’s a japanese blogpost which shows a DIY option, and references “Monthly I/O October 1991” as having some information. That would be nice to track down. Otherwise I might just see if I can reverse engineer how this thing (or the X68000 Pro board) works.

I am also curious if it would be possible to use this, while having RAM connected to the internal Slot 1 of a X68030, and that way bypassing the RAM issues. The manual does explicitly state to not use that port when the IO box is in use, so this is unlikely to be a good idea. Additionally, physically fitting a card in there is tricky when the IO-box extension is in place.