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I have a problem switching Banks using the MegaCart mapper for ColecoVision. I don't know if I have set ORG correctly for this Mapper. And does the CoolEM emulator see this Mapper at all?

And an important question - does this mapper also work with SG-1000?

Sample ColecoVision code skeleton - for example, I would like to switch SLOT $C000 to Bank 7 to load the screen's TileMap from it. If I move TileMap to $8000 or the first SLOT $C000, it obviously works, but trying to switch $C000 does not work.

.DEFINE SLOT_0          $fff8       ; For 128K Megacart (for 256K one I start on $fff0 upto SLOT_15 at $ffff)
.DEFINE SLOT_1          $fff9
.DEFINE SLOT_2          $fffa
.DEFINE SLOT_3          $fffb
.DEFINE SLOT_4          $fffc
.DEFINE SLOT_5          $fffd
.DEFINE SLOT_6          $fffe
.DEFINE SLOT_7          $ffff

;----------------------
ld hl,SLOT_7                ; switching code
call sel_slot                ; switch C000 to Bank7
;--------------------------

; code in slot7 $c000

;-------------------
ld hl,SLOT_0                ; witching code
call sel_slot                ; switch C000 back to Bank0
;------------------------

cv megacart bank wla dx.zip (214.59 KB)

siudym wrote

I have a problem switching Banks using the MegaCart mapper for ColecoVision. I don't know if I have set ORG correctly for this Mapper. And does the CoolEM emulator see this Mapper at all?

And an important question - does this mapper also work with SG-1000?

Sample ColecoVision code skeleton - for example, I would like to switch SLOT $C000 to Bank 7 to load the screen's TileMap from it. If I move TileMap to $8000 or the first SLOT $C000, it obviously works, but trying to switch $C000 does not work.

.DEFINE SLOT_0          $fff8       ; For 128K Megacart (for 256K one I start on $fff0 upto SLOT_15 at $ffff)
.DEFINE SLOT_1          $fff9
.DEFINE SLOT_2          $fffa
.DEFINE SLOT_3          $fffb
.DEFINE SLOT_4          $fffc
.DEFINE SLOT_5          $fffd
.DEFINE SLOT_6          $fffe
.DEFINE SLOT_7          $ffff

;----------------------
ld hl,SLOT_7                ; switching code
call sel_slot                ; switch C000 to Bank7
;--------------------------

; code in slot7 $c000

;-------------------
ld hl,SLOT_0                ; witching code
call sel_slot                ; switch C000 back to Bank0
;------------------------

What's the bank and page size on Colecovision?
8KB or 16KB?

It seems via https://forums.atariage.com/topic/216354-colecovision-megacart-faq/ that the megacart works by simply accessing memory in the $ffc0+ region to select corresponding 16KB banks into the single 16KB slot at $c000. The address accessed embeds the bank index, so I’d think of them more as bank select registers than slot numbers. The code you posted looks like a faithful conversion of the example code:

; For 128K Megacart (for 256K one I start on $fff0 upto SLOT_15 at $ffff)
SLOT_0: equ $fff8
SLOT_1: equ $fff9
SLOT_2: equ $fffa
SLOT_3: equ $fffb
SLOT_4: equ $fffc
SLOT_5: equ $fffd
SLOT_6: equ $fffe
SLOT_7: equ $ffff

; At start of code
ld hl,SLOT_0 ; Default slot of Megacart, but set again because user can do a Colecovision RESET
call sel_slot

; My typical switching code
ld hl,SLOT_3
call sel_slot

; Slot selection
sel_slot:
ld (slot),hl
ld a,(hl) ret
;

So… does the emulator you are using support it? I don’t know of any emulator supporting something like this for the SG-1000.

Unfortunately, I do not know.
blueMSX supposedly should work with MegaCart CV, but it doesn't launch either.

Author	Message
siudym Joined: 23 Sep 2021 Posts: 100 Location: Poland	ColecoVision MegaCart Bank Switching using WLA-DX Z80 Posted: Wed Apr 17, 2024 11:08 am
siudym Joined: 23 Sep 2021 Posts: 100 Location: Poland	I have a problem switching Banks using the MegaCart mapper for ColecoVision. I don't know if I have set ORG correctly for this Mapper. And does the CoolEM emulator see this Mapper at all? And an important question - does this mapper also work with SG-1000? Sample ColecoVision code skeleton - for example, I would like to switch SLOT $C000 to Bank 7 to load the screen's TileMap from it. If I move TileMap to $8000 or the first SLOT $C000, it obviously works, but trying to switch $C000 does not work. .DEFINE SLOT_0 $fff8 ; For 128K Megacart (for 256K one I start on $fff0 upto SLOT_15 at $ffff) .DEFINE SLOT_1 $fff9 .DEFINE SLOT_2 $fffa .DEFINE SLOT_3 $fffb .DEFINE SLOT_4 $fffc .DEFINE SLOT_5 $fffd .DEFINE SLOT_6 $fffe .DEFINE SLOT_7 $ffff ;---------------------- ld hl,SLOT_7 ; switching code call sel_slot ; switch C000 to Bank7 ;-------------------------- ; code in slot7 $c000 ;------------------- ld hl,SLOT_0 ; witching code call sel_slot ; switch C000 back to Bank0 ;------------------------ cv megacart bank wla dx.zip (214.59 KB)

siriokds Joined: 10 Dec 2009 Posts: 115	Posted: Wed Apr 17, 2024 12:07 pm
siriokds Joined: 10 Dec 2009 Posts: 115	siudym wrote I have a problem switching Banks using the MegaCart mapper for ColecoVision. I don't know if I have set ORG correctly for this Mapper. And does the CoolEM emulator see this Mapper at all? And an important question - does this mapper also work with SG-1000? Sample ColecoVision code skeleton - for example, I would like to switch SLOT $C000 to Bank 7 to load the screen's TileMap from it. If I move TileMap to $8000 or the first SLOT $C000, it obviously works, but trying to switch $C000 does not work. .DEFINE SLOT_0 $fff8 ; For 128K Megacart (for 256K one I start on $fff0 upto SLOT_15 at $ffff) .DEFINE SLOT_1 $fff9 .DEFINE SLOT_2 $fffa .DEFINE SLOT_3 $fffb .DEFINE SLOT_4 $fffc .DEFINE SLOT_5 $fffd .DEFINE SLOT_6 $fffe .DEFINE SLOT_7 $ffff ;---------------------- ld hl,SLOT_7 ; switching code call sel_slot ; switch C000 to Bank7 ;-------------------------- ; code in slot7 $c000 ;------------------- ld hl,SLOT_0 ; witching code call sel_slot ; switch C000 back to Bank0 ;------------------------ What's the bank and page size on Colecovision? 8KB or 16KB?

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14749 Location: London	Posted: Wed Apr 17, 2024 1:25 pm
	It seems via https://forums.atariage.com/topic/216354-colecovision-megacart-faq/ that the megacart works by simply accessing memory in the $ffc0+ region to select corresponding 16KB banks into the single 16KB slot at $c000. The address accessed embeds the bank index, so I’d think of them more as bank select registers than slot numbers. The code you posted looks like a faithful conversion of the example code: ; For 128K Megacart (for 256K one I start on $fff0 upto SLOT_15 at $ffff) SLOT_0: equ $fff8 SLOT_1: equ $fff9 SLOT_2: equ $fffa SLOT_3: equ $fffb SLOT_4: equ $fffc SLOT_5: equ $fffd SLOT_6: equ $fffe SLOT_7: equ $ffff ; At start of code ld hl,SLOT_0 ; Default slot of Megacart, but set again because user can do a Colecovision RESET call sel_slot ; My typical switching code ld hl,SLOT_3 call sel_slot ; Slot selection sel_slot: ld (slot),hl ld a,(hl) ret ; So… does the emulator you are using support it? I don’t know of any emulator supporting something like this for the SG-1000.

siudym Joined: 23 Sep 2021 Posts: 100 Location: Poland	Posted: Thu Apr 18, 2024 10:22 am
siudym Joined: 23 Sep 2021 Posts: 100 Location: Poland	Unfortunately, I do not know. blueMSX supposedly should work with MegaCart CV, but it doesn't launch either.

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