New to RC2014

[Martin Israelsen]

Hi All,

I wanted to say hi to the group. I built a Z80 kit back in the 90s (CXM-CPU from Circuit Design in Denmark. Z80 running CP/M plus). Lost the kit when I moved to the US.

Decided to try a new kit and ended up with SC720 and then continued with the SC792 Z180 and a number of other modules. Fantastic kits!

My next goal is to add a floppy module and hopefully read some of my old 5 1/4 disks :-)

A big, big thank you to those of you that have made this possible - Steve, Spencer and Wayne. The kits are easy to assemble and RomWBW is fantastic!

Martin

[Wayne Warthen]

Glad you are enjoying the kits.

Just one word of caution.  CP/M did not have a floppy disk format standard.  Each CP/M implementation was free to determine their own.  It is very unlikely that the RomWBW floppy format will be compatible with your old floppy disks.  Of course, you could dive into the RomWBW code and modify it to be compatible.

Thanks, Wayne

[Martin Israelsen]

Yeah, I expect I'll have to dive into the code and play with skew rate and what not. I seem to remember that somebody created a program that could read other manufacturers CP/M disks so I'll search the net for that too.

Thanks again for RomWBW it is really great to use.

Martin

[free...@gmail.com]

This topic thread reminds me of the Greaseweasel, perhaps something similar could be created for the RC bus.

Justin  

[Alan Cox]

On Tue, 11 Nov 2025 at 20:12, free...@gmail.com <free...@gmail.com> wrote:

This topic thread reminds me of the Greaseweasel, perhaps something similar could be created for the RC bus.

 

That's more about physical formats. You need some level of hardware support if you want to do anything like Greaseweasel without a modern high performance microprocessor. It can be done and in fact it was. The Commodore 128 had a strange dual life as a fancy Commodore 64 and a terribly bad CP/M machine but it was used extensively for disk copying as there was little in normal GCR or FM/MFM formats that the 1571 drive couldn't read or write.

The 1571 is a very clever piece of technology though so it's not a small project to clone.

The standard controllers used in the RCBUS cards will read most physical formats but you do need to know stuff like sector lengths and density and geometry to make it work. Most CP/M systems used standard IBM derived physical formats so the only other trick you then need to know is that 8" disks are clocked differently so 8" DD is equivalent to 3.5" HD. With that and a fast enough CPU there's not a lot you can't read except GCR formats. 3.5" HD will probably need a DMA controller, a faster than RCBUS CPU or some truly insanely ugly trickery.

You should also try to read the physical media once as a disk imaging read anyway. The surface on the old disks is often not stable so you may not get many goes at reading it, especially if it's got any traces of mould. For extremely valuable media (like believed rare one off copies of historically signifcant data) people go as far as imaging the flux patterns on the media without physical contact of any kind!

Alan

[Greg Holdren]

22Disk, Teledisk if my memory is correct.

Greg