Booting from df1: is possible?

[ikonsgr]

There is a very quick and easy way to "transform" any external drive connected to AMIGA 500 to a real DF0, meaning amiga will recognise the external drive as DF0 (of course the internal drive is disabled)
Check the photos to see how it's done:
http://i.ebayimg.com/00/s/MTQxOVgxNjAw/z/jeYAAOSwuYVWpf-m/$_57.JPG
http://i.ebayimg.com/00/s/MTQ0OVgxNjAw/z/VCUAAOSwLnlWpf-0/$_57.JPG
http://i.ebayimg.com/00/s/MTQzNVgxNjAw/z/TyoAAOSwa-dWpf-3/$_57.JPG

[Jope]

Yep, the a1000 is rather different to the a500/b2000. Lots of discrete logic was integrated to the gary chip.

[Keir]

Originally Posted by r.cade

I tried putting SEL0/SEL1 on a switch from pulled pins to sockets and cross them on my A1000, but the SEL0 signal also goes somewhere else on the board and this does not work totally.

When switched, the external drive is DF0, which is what I wanted ultimately (Gotek) but the internal drive does not work as DF1 this way (no response). Switched back the other way, all works (DF0 internal, DF1 external). Is the A500 board different where this works properly or is there more to this mod than that, or is the internal drive never going to work with this mod?

What you want (DF0 external, DF1 internal) requires you to swap the SEL0 and SEL1 pins on the CIA. That's mechanically a bit more tricky than just bending a sequence of pins 'across by one'.

[Keir]

Originally Posted by asapreta

I just saw elsewhere I need to reroute MTR0 and MTR1 signals too. Does anyone have an schematic for this?

Best regards.

You actually need some more circuitry to make an external drive interface, the MTRX line needs to be latched into a flipflop on asserting edge of SEL1. This generates MTR1 for the floppy drive. And properly speaking you also need to assert RDY when SEL1&!MTR1. This is used by AmigaDOS to identify that an external drive is present. Google up "amiga floppy external schematics" for some examples, some of the schematics are buggy though!