In development - SD card based Multicart

[Stephen J. Carden]

Hi All,

 

I thought I'd post to announce my new hardware project - I'm building an SD-card based Multicart.

 

https://youtu.be/PjkCTXqirv8

 

Although its far from being finished, it already shows the available ROMs/CARs on the SD card on an Atari menu, and will then reboot to the selected cartridge. At the moment it only supports 8k ROMS and 8-mbit Atarimax ROMs, with bankswitching etc, but I plan to support all cartridge types soon.

 

Adding a new ROM is simply a case of copying a new file to the SD card - no more flashing ATRs etc.

 

Not sure if there's any other available hardware that currently does this? I don't have an SIDE or MyIDE.

 

The hardware is a Altera Max 10 eval board, with my 3.3v cartridge breakout board attaching it to the atari. There's an external 1 megabyte SRAM which cartridges are copied to. Initially the atari boots to a small 8k boot ROM which is stored in dual port memory on the FPGA. The FPGA is also running a soft-cpu to copy files from SD card to SRAM.

 

I'm planning to make a PCB for this next, with the aim of fitting inside a standard cartridge case. Never done an FPGA board before, so that may take me some time. The boot ROM is also far from finished - I'm having to learn 6502 from scratch.

 

There are some other possibilities for this too - the same cartridge could be re-programmed e.g. as an atari co-processor/accelerator board. I'm planning to leave a JTAG/USB Blaster header on the board to make this easy.

 

Robin

 

ultimate_cart_prototype.jpg

 

 

Here is something I hope you find useful. Here is the bank switching info I have for programming.

 

;==========================================================================

; Express! Professional Terminal Program

;

; Copyright © 2001 Stephen J. Carden

;

; This module contains all of the global definitions.

;

; Compiler: MADMAC Cross Assembler

;==========================================================================

.atascii ;translate IBM chars to ATASCII chars

; system cart equates

; ~~~~~~~~~~~~~~~~~~

screen equ $bc40 ;change to $9c40 when in ROM!

;screen equ $9c40 ;change to $bc40 when in RAM!

;

;phone_book: equ $a000 ; when in cartrage

phone_book: equ $4000 ; when in ram

 

my_crc_low equ $2d00 ;$a200

my_crc_high equ my_crc_low+256 ;$a300

;LFFE4

;

all_bank equ $d500 ; Steve Tucker Mega Cart

;

;all_bank equ $d570 ; Express cart latch

;

;all_bank equ $d5d0 ; Diamond GOS latch

;

;all_bank equ $d5f0

;

; ; express cart!

bank0_latch equ all_bank+7 ;$d577 ;highest bank in the cartridge

;

car_pass equ all_bank+8 ;$d578 ;enable cart pass-thru

passthru_latch equ all_bank+9 ;$d579 ;

cart_off equ all_bank+12 ;$d57c ; cart off

;

x_cart_tag equ $ffe4 ;d5e8

;

[flashjazzcat]

The cart fits in an 800 with the door closed, BTW.

[+bcombee]

Have you posted this to GitHub yet? I'm curious at looking at the design files and seeing if I want to try to fabricate my own.

[electrotrains]

Have you posted this to GitHub yet? I'm curious at looking at the design files and seeing if I want to try to fabricate my own.

 

Yes - see the new(er) technical thread:

http://atariage.com/forums/topic/241888-ultimate-cart-sd-multicart-technical-thread/