Compile 4k+4k

[Cisano]

Hi. My game needs 8k.

I use Visual Studio.

Bank 0

    org  $1000

    rorg $1000

;code

    org  $1FFA

    rorg $FFFA

Bank 1

    org  $2000

    rorg $1000

;code

    org  $2FFA

    rorg $FFFA

I know how to swtch the banks, thank to 8bitworkshop.

My question.

The code must be in the same file? Because I have "Failed to create compiled file" error. No other help about the reason.

Thanks.

[+splendidnut]

It might just be a typo, but org (binary file origin) should start counting from $0000, not $1000.  Also rorg (relocated "code" origin) should be within a 4k region ($1000 .. $1FFF, or $F000..$FFFA) for the start and end of each of your banks. Fixed in the following:

 

Bank 0

    org  $0000

    rorg $1000

;code

    org  $0FFA

    rorg $1FFA

Bank 1

    org  $1000

    rorg $1000

;code

    org  $1FFA

    rorg $1FFA

[Cisano]

Are you sure about the values for the Bank 1?

Because I continues to get error.

[+splendidnut]

I just tried this and it worked:

 

;------------------------------------
;---- 8k DASM example

    processor 6502

;-----------
;-- Bank 0
    org  $0000
    rorg $1000

    
    lda $1ff8
boot:
    ;put code here

    
    org  $0FFA
    rorg $1FFA

    word 0
    word boot
    word boot

;-----------
;-- Bank 1
    org  $1000
    rorg $1000
    
    
goto_boot:
    lda $1ff8   ;-- switch back to bank 0 and continue execution at "boot"

    ;put code here
    
    org  $1FFA
    rorg $1FFA

    word 0
    word goto_boot
    word goto_boot

 

[Cisano]

It works, thanks very much.

[Cisano]

One last thing. From 8bitworkshop:

MAC BANK_SWITCH
.Bank	SET {1}
.Addr	SET {2}
lda #>(.Addr-1)
ldy #<(.Addr-1)
ldx #.Bank
jmp BankSwitch
ENDM

Having 2 label with the same name in the 2 banks "BankSwitch", I get "Label mismatch" error.

How to fix it?

 

You use:

lda $1ff8

Is it enough to use lda instruction for the switch?

Thanks for every info.

[+splendidnut]

Yes, reading/writing to 1FF8 (for bank 0) or 1FF9 (for bank 1) will switch banks in the 8k/F8 bank-switching scheme.  But, you need to be careful because the bank-switching happens immediately.

 

The code in 8bitworkshop is quite complex.  I don't really have any experience with using techniques like that.   In PaintTheCity, I use a much simpler technique which involves defining a jump table at the beginning of each bank.  (ChaoticGrill also uses a similar jump-table technique)

 

Here is an example of the jump-table bank-switching technique.  This example shows a layout where Display code and Graphics data would be located in bank 0, and game logic would be located in bank 1.

 

F8_banking_example.asm

[Cisano]

I've taken the decision to use the code in F8 banking example.

It works and from Bank1 pressing the fire button it goes in the Bank0 and the game starts.

I have this problem now. The Bank0 has free memory.

 

If I write some instuctions (it doesn't matter which) I get, just started, "invalid instruction" by Stella.

If I delete one and check, one and check, etc ... it begins to work again.

The funny thing is, that code is not executed.

Thanks for every info.

 

[Cisano]

I have understood the problem.

I use

align $100

for a big sprite.

This create a strange problem in both the banks.

Anyway it seems fixed.