bootstrap.asm

*----------------------------------------------------
* Emulator bootstrap rom for Coco3 NitrOS9.
*
* After assembly boottrack with boot_emu is appended.
*   ops="--raw -D DISKROM=1 -D H6309=1 -D DEBUG=0"
*   lwasm $ops -o bootstrap bootstrap.asm
*   cat bootstrap boottrack > bootstrap.rom 
*   truncate -s 8192 bootstrap.rom
*
* E J Jaquay 2024.09.27
*----------------------------------------------------

 PRAGMA emuext

 org $C000

* When Super Extended Basic sees a rom starting with "DK" it 
* is processed as a disk11 rom. Basic copies it to ram then 
* makes changes to it before jumping to $C002. We need to set 
* back to ROM mode to not see those changes.

 IFNE DISKROM
  fcc "DK"       ROM to disk11 rom 
  lda #$CC       Tell GIME to 
  sta $FF90      map 16k external
  clr $FFDE      Switch to ROM mode.
 ENDC

* Copy bootstrap containing REL, BOOT, and KRN to $2600.
* REL will copy these to $ED00 and run them.  It is possible
* to copy bootstrap to $ED00 directly by switching back and
* forth between ROM and RAM modes as chunks are copied but
* this is not done here.

 ldu #boottrack where the bootstrap modules are
 ldy #$2600     where they are copied to low RAM

 IFNE H6309
  ldw #$1200    bytes to copy
  tfm u+,y+
 ELSE
  ldx #$1200    bytes to copy
cpy ldd ,u++
  std ,y++
  leax -2,x
  bne cpy
 ENDC

* For debugging break to check the copy

 IFNE DEBUG
  break
 ENDC

* Jump to start of REL. REL will relocate the modules to high
* memory where they will stay resident until system goes down.

 jmp $2602

boottrack

* Bootstrap modules REL, BOOT, and KRN will get appened here.

 end