nfg.forums

So back to this.

I did more RE work. Here is how marty works.

Marty runs just like the computers with a special CRTC that takes an input of digital RGBHV along with an NTSC subcarrier frequency thats exactly 8x the 480i clk specification.

The CRTC divides by 8, performs RGB to YUV colorspace conversion, and outputs 2 channel 8 bit video to the svideo DAC. It also outputs composite video. So technically its a mixed signal ASIC.

You can regenerate csync if you AND the hsync and vsync together with a NOT blanking signal into it. The issue is that CRT and PVM cannot accept 24khz signals. So it would be a moot point in modding it for RGBS. RGBHV however is totally possible but I have yet to know if anyone is interested in such a modification. I think the Towns operates on 18 bit RGB.

Quote from: solidpro on April 24, 2024, 02:38:17 AMI've found this mod https://nfggames.com/forum2/index.php?topic=6499.0 to turn an ATX power supply into a compatible one for the FM Towns. I wondered if, like on ATX you can ground the GREEN pin with a BLACK to auto-power-on, there is a similar pin on the FM Towns PSU....?

Here is how all towns power supplies work:

Power on signal switch goes to GND. Kicks on and off PSU with discrete logic on PSU.

Towns OS off pin goes to GND. PSU turns off.

You can wire an ATX directly to the connector on mainboard if you know the pinout which is trivial to solve. Just desolder wiring harness from dead PSU and find what pins are GND, 12v, -12V and 5V. Then wire an ATX to it. When ATX switch is turned on, the pc will turn on. Only downside is the PSU can only be controlled by ATX on and off switch, and not the towns OS OFF or original power switch.

This is all assuming you cant troubleshoot whats wrong on the original.

Hey, if this is still available please shoot me a PM!  I can post other socials and my ebay to show credibility and totally willing to do a goods/services PayPal exchange with me covering the extra fees.

Let me know thanks!

I've found this mod https://nfggames.com/forum2/index.php?topic=6499.0 to turn an ATX power supply into a compatible one for the FM Towns. I wondered if, like on ATX you can ground the GREEN pin with a BLACK to auto-power-on, there is a similar pin on the FM Towns PSU....?

Hey Everyone

I bought an FM Towns II-HR which was powering up fine and then just decided not to do anything. I disassembled the machine and completely recapped the power supply with new RS-Components caps and it still doesn't power on.

There is about a 10% chance that on the PSU, I got capacitors C58 and C52 the wrong way around (1 of them is 2200uf and the other is 1000uf) - does anyone have a point of reference for the II-HR PSU as to what these two caps are?

Having said that, I suspect it would power on even if they were switched, so it must be something else. I can hear a very slight hum when the PSU is plugged in, me thinking it's getting power. The power button is 'soft' so I don't know if there is another way to insipire a power on?

Also there are *a lot* of electrolytic caps on the mainboard, so I didn't replace them - I could not spot any signs of leakage. But could that be worth doing?

Thanks

Thank you

Not sure on Super (SCSI I think).
Does SRAM still need setting to tell it to boot from HD?
Battery is now probably dead, so SRAM could need setting up.
So boot floppy Master disk and type switch.x and check options.

Also you sure you have not removed the CF card 10 years memory:)

Also the App called 'Papago' (I use on Android) is great at Japanese translation.

@bobrocks95 ok, so you don't physically have your X68000 yet just doing the ground work. No problem.

Yes you need a way of loading floppy disks images or physical disks to install the SCSI driver to allow HD access. Chicken and egg.

Are you ok with soldering and stuff?

I would buy IDC ribbon cable (50 way) and IDC connectors ready to make floppy and HD cables. (Can use a vice instead of proper IDC crimp tool to save some money).
You can also use to make either 20 or 26 pin SASI internal cable.

Is your X68000 coming with any disks? Otherwise you might go to the effort of sourcing a Master disk only to find your disk drive needs refurbishment or it is not fixable (seems to be 4 small caps that leak).

A Gotek connected to external floppy port is simple/cheapest option. Do you have one with other Retro hardware you can borrow? You only need it to install the SCSI driver, then can disconnect.

But with 2mb only, you will be limited to what you can run from HD image.

Finally where in the world are you?

Good Morning. I've now managed to boot my X68000 with a floppy. Connected via VGA, decent picture.

When I last used it around 10 years ago I was using a cf card to boot a pre done image, lots of games on it.

I can't remember if it booted automatically when I switched the machine on or I had to type in a command ?
Any help on this is greatly appreciated. I have sadly forgotten how to use the machine I've the years.

Forgot to say it's a super hd model. The hd busy light is on, but it ask for a floppy to be inserted

Quote from: HIggy on April 22, 2024, 05:39:38 AM@bobrocks95 Hi. I would go for a BlueSCSI V1, it is the cheapest and easiest option. You can connect to the connector on the back and fit it inbetween the 2 towers. You will need to make a cable.

You will need the SxSI driver. If you don't have battery backup then you will have to install every time you power on, otherwise you just install it once.
It installs to the SRAM so needs battery backup to keep settings.

It is easy to install, there is a Master disk image that has the SxSI driver. There is a few things to type in but it is easy.

I've now mounted my BlueSCSI V1 internally and have a Arananet 50 pin SCSI to 20pin SASI adaptor with HD light connector, but they are out of stock.

Floppy Drive emulators - they are good if you don't have extra ram for running games. But also good if your internal drives are broken.
I guess most options are custom Japanese devices, but a Gotek works well (also need an Eject/Insert logic box to make fully compatible).

Thanks for the info HIggy!  I have a replacement battery circuit on the way so that doesn't sound bad, still waiting on the actual X68k to see how the refurb goes though.

I'm still a bit lost on how that master disk image will go though.  If I don't have the SxSI driver installed already, then I can't use the BlueSCSI to install it, so I'd have to have a floppy with the driver on it, right?  Which I would think means buy an old 5" PC drive and write it to one, or pay somebody for a copy on one.

Unless the machine can somehow access the BlueSCSI without the SxSI driver in some limited capacity?


I'll have to see what the pin count is on my SASI connector, looks like there's 20 or 26.  Yahoo Japan has some cables I've seen pop up, and I like the idea of internal, even if it's an annoyance to swap things out.