Thanks again, Paul, for the link to your basic rom package. Of course, that
version is
running but I'd really like to have the advanced 1.1 features inside ;)

After fiddling with your 1031 basic I still had no luck in applying a basic ROM
replacement
patch on the current version. Maybe you remember what has to be done? What I
could see
after looking at the binary structure is like this:

--------------------------------------------------------------
cnth1031.basic header disassembled:

$0000 94 E3 ; pointing to kernal reset routine E394

$0002 7B E3 ; pointing to kernal warmstart entry E37B

$0004 0D A0 ; guess this points to where the hacked basic.rom is appearing
(starting at
$A000) - pointer to kernal subroutines (see $000D)
$0006 0D A0 ; same

$0008 C3 C2 CD 38 30 ; Autostart command "CBM80" - but I think this is
redundant,
there's nothing at $8000?!?

$000D 78 ; SEI - set interrupt mask

$000E 20 84 FF ; jump to kernal subroutine FF84 = init I/O devices

$0011 20 87 FF ; jump to kernal subroutine FF87 = init memory pointers

$0014 20 8A FF ; jump to kernal subroutine FF8A = restore I/O vectors

$0017 20 81 FF ; jump to kernal subroutine FF81 = initialise screen / keyboard

$001A 58 ; clear interrut mask

$001B-0028 EA ; NOP - no operation (guess not to crash kernal routines looking
for
BASIC things around there?)

$0029-0482 FF ; not used

$0483 ; program starts here (ROM appearing at $A483 = standard BASIC warmstart
routine - guess this is where the Kernal is starting the program after init
sequences.

$0CFA ; end of program code (followed by FF to fill the 8K ROM)

--------------------------------------------------------------

However what comes now, how to put in program code after $0483?

I think the basic starter (SYS 2061) has to be removed. How about absolute and
relative
addresses? Did you tweak them manually to get Cynthcart1031 running off the
BASIC
ROM? Could you maybe provide the unpatched Cynth1031.PRG so I may compare the
code
to solve the mystery?

Besides running Cynthcart without a cartridge attached it would be nice to
improve
breadbox knowledge anyways ;)

Thanks for your attention.

ron.