Floppy disk controller

[Stéphane Pitteloud]

Hi, I have a small question: if I want to use a floppy controller with a real floppy drive on the expansion bus, how can I configure the altairduino to tell him to actually boot on the real floppy and not on the emulated one? Is it possible to still use both (real and emulated) to make a copy of the floppy image on a real floppy? Thanks :-)

[John Galt]

you go into the config menu and disable your DSK images for the floppys leave them empty then it will go to the physical floppy drive to read the disk.

you can't have one emulated and one real drive when using the real drives so make sure both are unmounted when using the disk drive.

to make a copy of the disk you can use a CP/M utility for single drive machines  it will copy using a buffer,.

or the MONITOR that is part of the drive card will backup a floppy and create a DSK file. you have to be connected to it with a terminal of somekind like Teraterm on a pc or mac.

you can also install the original Disk roms on to the Arduino 

so when you boot to a floppy now you flick Sw3 up then run and it will boot off the real floppy drive.

if you want more realism you can put the real roms at FF00 and the hard drive rom at FC00

then you flip FF00 on the address switches and Stop, Reset, examine, run and it will boot from the floppy or FC00 for the harddrive.

the hard drives are emulated so those are mounted in the config menu.

[John Galt]

there is a format utility from the CP/M lifeboat disk that will format 330KB disks also.

[Stéphane Pitteloud]

Thanks for all the infos!

My idea was more to copy the floppy images on a real disk, there is no way to achieve this? How do you guys create your real floppy?

[Patrick Linstruth]

I have never tried this on the Arduino, but I would think the PC2FLOP utility would work. It will transfer a disk image over Xmodem.

https://deramp.com/downloads/altair/software/8_inch_floppy/Disk%20Image%20Transfer/

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[John Galt]

yes, you use the monitor to copy a DSK image onto a real disk. you can upload a DSK image onto the floppy any of the 330KB sized disk images.

you can then make a new disk with your files and using the monitor copy them through the monitor into a new DSK file. this creates a new 330KB disk image.

or you don't have to use the monitor you can format a new disk and copy your files to your disk then duplicate the disk using cpm utilities.

i would recommend pre-formated floppies, i had issues with unformated 1.2MB disks not working and i had to IBM format them first for the monitor.

once i copied a FORMAT.COM utility to CP/M i could format the new disks that way, but some times i still needed to preformat things to avoid issues.

i will warn you using 2 disks can be problematic as both drives have to be close to each other with head alignment. otherwise one disk will work in one drive and not the other.

[John Galt]

the monitor is part of the Disk controller board for the I/O Bus.

you press the 2 buttons on the card, reset and monitor then release reset and hold monitor and it will connect via usb to a terminal

so if you have a laptop next to the disk controller you hook it up and connect at  115200 baud on that new com port. that will give you access to the monitor.

then you Xmodem transfer the disk image back and forth.

[Stéphane Pitteloud]

this is a very good idea, I hadn't thought of it! Thanks

[Stéphane Pitteloud]

interesting... So, If I understand right, the monitor on the floppy controller take the control of the Altair when I press the two buttons? The monitor need certainly some commands to copy the image I send via Xmodem, or it is automatic?

Many thanks for your help

[Chris Davis]

The monitor on the floppy controller does not interact with the Altair-Duino. All communication happens through the FTDI serial to usb on the drive controller.

[Stéphane Pitteloud]

I have to plug the USB cable directly on the drive controller? It's a specific cable/adapter then?

[Chris Davis]

Yes.  Just a micro USB cable.  Did you buy the drive controller kit?

[Stéphane Pitteloud]

Not yet, this is why I don’t see how to connect this. 

[John Galt]

Basically the disk controller card when plugged into the backplane and powered will function as a standalone device.

it will be connected to the Altair but there is a side micro USB port on the card. 

you setup your usb cable to the side of the card then connect via teraterm or your terminal software.

you press reset and monitor, release reset and the monitor menu will appear on the terminal.

when the monitor is activated you cannot access the drives through the altair.

you press h and the monitor gives you options.

do what you need with your disks at that point transfer a new disk image via xmodem from your pc or mac to a new floppy disk.

run diagnostics etc.

when you press x the monitor will quit and return control to the i/o bus with the altair.

the disk controller is can be a stand alone device in a way.

[Stéphane Pitteloud]

Ok, thanks, now I understand. But I’m failing to see any USB plug on the board when I’m looking at the pic here

https://adwaterandstir.com/product/disk-controller-card/

[Chris Davis]

Take a look at the instructions.

[Chris Davis]

In the original you were expected to add your own serial connection (typically a MAX3232 module).  I have started including an FTDI module with the kit.

[John Galt]

trust us, i was apprehensive to do this. It is worth it and will make sense.

a complaint you will see is the location of the 2 buttons on the disk controller board are a pain to get to. i installed 2 remote buttons for my I/O Case. just solder some leads on the back side of the board and you can have the same remote buttons making getting into the monitor easier.

[John Galt]

here is my side usb connector.

[Stéphane Pitteloud]

This is what I did: I took a look at the GitHub and saw:

"The serial port present on the card can be connected to a PC via an FTDI USB-to-serial converter and has two functions:"

[Stéphane Pitteloud]

nice!

[Stéphane Pitteloud]

ok, thanks for the info!