Author: buffi

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.

Went and bought something silly for my X68030, a old Nereid card which extends it with USB and Ethernet.

Setting it up was surprisingly easy. Loaded the drivers in the included floppy and followed these instructions, and everything just kindof worked for Ethernet right away.

Have it hooked up to my router and could jump on IRC with the CLAT client.

Pretty happy with this, and sortof want to keep using this as a IRC chat device for the fun of it. Will have to swap out the fan for something more quite though since the X68030 still runs on original power supply with a fan that’s a bit too loud for me to want to have it on all the time.

Messed around a bit with the available web browsers, but honestly… they’re not really something that’s particularily usable. IRC is neat though, it’s been a while since I’ve been using that.

Still need to mess around with the FTP software for X68000, since that might actually be kindof useful. Currently I’m transmitting files to it by modifying the HDD image loaded through BlueSCSI. I’m not sure using FTP is much better, but it’s at least a cool option!