720K Gotek images on the PCW 8256/8512?

[pollito]

I recently Gotek-ed up my 8256, and was wondering if it is possible to use 720K DSK images on the USB stick?

I am using CP/M Plus v2.9, and when I select a 720K image on the Gotek, I get:

Code Select Expand

Disc unsuitable - Retry, Ignore or Cancel?
I was thinking that a later version of CP/M Plus might help, but anything higher than 2.9 refuses to boot.

Perhaps a FID might help? I don't necessarily need to boot off a 720K image, but it would be great to be able to access them post boot. I'm currently feeling the limitations of 180K! 

Thanks in advance for any suggestions!

[robcfg]

Can you mount the image as drive B:?

[pollito]

Can you mount the image as drive B:?

No, the Gotek only emulates one drive, which is A:

At the moment there is no physical drive fitted, and that will probably stay like this because I've also got an 8512. With the 8512 I will be changing the top drive (A:) for a Gotek, and replacing the drive belt in the lower drive (B:). That way I will still have one physical drive.

[JohnElliott]

To get past the hang on booting with later versions, try ejecting and reinserting the disc image. A proper fix requires a hardware modification.

[pollito]

To get past the hang on booting with later versions, try ejecting and reinserting the disc image. A proper fix requires a hardware modification.

Thank you for your suggestion. I tried to boot with the 720K images of CP/M Plus v1.12, and v2.15.

With v2.15, I just get three beeps every time. However, with v1.12, the horizontal lines appear until they are around 1/3 from the top of the screen. Then the screen goes green, immediately followed by black.

If I remove the USB drive at this point, the CP/M screen appears, complaining that there is no disc in the drive. Reinserting the USB stick, and hitting R to retry continues the boot process. I can then access any 720K image without any issue. However, 180K images are no longer readable! 

What's happening here? I believe the v1.12 image was intended for the PCW 9256/PcW10. Does the screen turn black due to some driver issue during boot, which is then aborted when the disc is ejected?

And, is there a 720K driver on the v1.12 image, and a 180K driver on the v2.09 image that I usually boot from? If so, is it possible to have both loaded so that 720K and 180K images are swappable?

You mentioned a hardware modification. What does this fix, and how?

Also, how does versioning work with the PCW's CP/M Plus? Is v2.09 later than v1.12 or does the first number mean something else?

Feel free to just send me some links in answer to some of these questions if they've already been answered before! 

[JohnElliott]

In order:

• The 2.15 disk probably didn't boot because the boot sector is for a 9512. Dot-matrix PCWs (8256, 8512, 9256, 10) reject boot sectors intended for daisywheel PCWs (9512, 9512+) and vice versa.
• PCWs think a drive is either 180k or 720k. If it thinks a drive is 720k, it tries to double-step when reading 180k discs. That's the right thing to do with 3" drives, but not with 3.5" drives or Goteks. I created a patch to improve this - DLOGINPW.FID which you can find in XLOGIN.PMA at https://www.seasip.info/Cpm/software/amstrad.html. Put DLOGINPW.FID on the boot disk and (if CP/M is recent enough) it'll sign on at startup.
• The hardware modification is to make the Gotek respond only if both the select and motor signals are low - normally it can be configured to respond to one or the other but not both. See https://fabriziodivittorio.blogspot.com/2018/05/installazione-gotek-su-amstrad-pcw-9512.html
• CP/M version numbers are 1.x for dot-matrix PCWs and 2.x for daisywheel PCWs. If you start 2.x on a dot-matrix PCW or 1.x on a daisywheel PCW, it will work but the built-in printer will show as not connected.

[pollito]

In order:

• The 2.15 disk probably didn't boot because the boot sector is for a 9512. Dot-matrix PCWs (8256, 8512, 9256, 10) reject boot sectors intended for daisywheel PCWs (9512, 9512+) and vice versa.
• PCWs think a drive is either 180k or 720k. If it thinks a drive is 720k, it tries to double-step when reading 180k discs. That's the right thing to do with 3" drives, but not with 3.5" drives or Goteks. I created a patch to improve this - DLOGINPW.FID which you can find in XLOGIN.PMA at https://www.seasip.info/Cpm/software/amstrad.html. Put DLOGINPW.FID on the boot disk and (if CP/M is recent enough) it'll sign on at startup.
• The hardware modification is to make the Gotek respond only if both the select and motor signals are low - normally it can be configured to respond to one or the other but not both. See https://fabriziodivittorio.blogspot.com/2018/05/installazione-gotek-su-amstrad-pcw-9512.html
• CP/M version numbers are 1.x for dot-matrix PCWs and 2.x for daisywheel PCWs. If you start 2.x on a dot-matrix PCW or 1.x on a daisywheel PCW, it will work but the built-in printer will show as not connected.

Many thanks, John; I tried DLOGINPW.FID on the 720K disc images, and sure enough I can now read 180K disc images with it (although I have to press [STOP] or [ALT] + [C] when switching between the two, presumably to reset the disk system). It doesn't work on a 180K boot disc for some reason, though - the driver loads fine, but 720K images are not accessible. This isn't important, of course, just an observation. 

Regarding the mod on Fabrizio's page, I did read this page when I was installing the drive, but it says:

With only one drive, the solution is simple: just back the jumper from S0 and place it on MO. This way, drive A is selected whenever MO LOW, instead of S0, what is ignored this time is.

I tried this, however the Gotek was then causing the system to think there were two drives installed in the machine instead of just one, drive A: being the only working one. This made it impossible to copy files between images on the PCW. After moving the jumper from M0 back to S0, only one drive showed, so I thought everything was working fine.

It seems that any version I try over v2.9 causes the issue where the screen turns black on boot, and I have to re-insert the USB stick.

Do you think that adding Fabrizio's circuit would fix the issue? If so I may design some PCBs for this in KiCAD, as I will need one for my 8512 anyway, and it would be nice to have something on Github for this as PCB manufacture is so cheap these days.