I'm building an Amiga Turbocard relocator board for the A1000/A500 expansion bus.
The A1000 cannot load a modern Kickstart to its 256kB WOM so it cannot directly use a Kickstart 2.04 or 3.0 and requires an EPROM/Flash card to be able to boot with a TF536.
That's why I added a 1MB Kickstart Flash to my relocator board which maps two memory regions:
- $F80000 to $FFFFFF for a 512 kB Kickstart (read only)
- $E00000 to $E7FFFF for a 512 Expansion ROM (read/write) and it is also used for the programming of a new Kickstart
That way either two Kickstarts can be programmed or one Kickstart and a 512 kB Expansion ROM at $E00000.
Both areas assert the /OVR pin to deactivate the Amiga address decoding (primarily for the Kickstart ROM/WOM) and create /DTACK themselve.
7M is synthesized as "7M=/C1 XNOR /C3".
When I try to reprogram the Kickstart using the $E00000 memory area I get an error when reading the identification of Flash Chips, so I cannot program them.
I also get no Fast RAM detected. I'm not sure if this is related therefore I'm mentioning it here, but this is another story and I'd like to look at it after solving the $E00000 issue.
Now my questions:
- Is the TF536 using the $E00000 memory area for its own purpose?
- Is it using any other area, e.g. $F00000-$F7FFFF?
- Any other idea, why it doesn't work (e.g. caching could by a problem)?