MEGAMAX Cartridge V1.2   german here


Here I´d like to introduce my new project "MEGAMAX Cartridge". Before going into detail, here are some highlights:


- 100% compatible with the AtariMax MaxFlash 8 Mbit (1 Mbyte) cartridge

- The MEGAMAX cartridge can be read and written (!) with the AtariMaxFlash USB Cartridge programmer.

- Up to 2 Mbyte of space in 16 KB mode or 1 Mbyte in 8 KB mode.

- 8K mode AtariMax compatible up to 1MB, bank switching via address lines.

- 16K mode similar to MEGACART cartridge up to 2 MB, bank switching via address lines (MEGACART cartridges use data lines)

- optional use of one or two memory chips

- optional use of EPROMs, PROMs, Flash-ROMs or SRAM

- buffered battery possible in SRAM mode

- separate write protection switch (Flash-ROM/SRAM)

- cartridge can be completely disabled by a switch

- RESET-button (not existent at the genuine AtariMax flash cartridge) avoids the need of switching off the Atari

- internal cycle optimization makes sure it runs trouble-free on every genuine XL/XE

- rock solid, CNC shaped aluminum housing with more space (length now is 10cm!)

- can be screwed open any time! 


Got curious?


Here some pictures of the prototypes and the finished cartridge in housing:



First prototype with wirewrap  and 2MB NVSRAM...



First assembled board...



Ready assembled final-cartridge with jumpers for chip configuration (EPROM/FLASH/SRAM etc.)



Mounting into the aluminum housing...





Finished cartridge in operation...


To use the MEGAMAX cartridge there is no need of having an AtariMax USB Cartridge Programmer.



The version with Flash-Roms or SRAMs does not need any additional hardware and can be programmed directly with the Atari.

The use of EPROMs of course requires a EPROM-burner.



Memory options 


These are the possible armaments  of the MEGAMAX cartridge:


With SRAM (e.g. Hynix HY628400A or BSI BS62LV4006Px) one 512 Kbyte or two 512 Kbyte SRAMs (together 1 Mbyte) can be equipped. The 1Mbyte can be used in 8KB or 16KB mode.


With Flash-ROMs (currently guaranteed supported by software is:  AMD 29F040B) one 512 Kbyte or two 512 Kbyte Flash-ROMs (together 1 Mbyte) can be equipped. The 1Mbyte can be used in 8KB or 16KB mode.


With EPROMs (or PROMs) either 27C040 (512 Kbyte each) or 27C080/27C801 chips (1 Mbyte each) are possible. One or two chips of the same type can be equipped at the same time. The armament of 512 Kbyte (one 27C040) or 1 Mbyte (two 27C040 or one 27C080/27C801) can be used in 8KB or 16KB mode. The maximum armament with two 27C080/27C801 (2 Mbyte total) can only be used properly in 16KB mode.


The internals


The MEGAMAX cartridge is controlled by two GALs and therefore could be adapted to other extensions by exchanging or reprogramming the GALs.


Like the AtariMax MaxFlash cartridge does, the content of the MEGAMAX cartridge´s memory chips is selected through bank switching. It is realized by accessing the cartridge control register starting at $D500 in the hardware I/O area of the Atari. The programming is simple:


Access (read or write) at $D500: bank 0 active (this is standard after switching on the Atari or pressing the reset button of the MEGAMAX cartridge).


Access at $D501: bank 1 active - etc. to $D57F - bank 127 active.


Access to $D580-$D5FF switches the cartridge off. Renewed access to $D500-$D57F switches it on again.


The number of maximum available banks results from the memory equipped and the chosen mode (8 KB or 16 KB). 


In 8 KB mode there are 64 banks at 512 Kbyte or 128 banks at 1 Mbyte possible. 

In 16 KB mode there are 32 banks at 512 Kbyte, 64 banks at 1 Mbyte or 128 banks at 2 Mbyte (only possible with EPROMs) possible.


The 8 KB mode means, that 8 Kbyte ROM are inserted at memory area $A000-$BFFF of the Atari. Line RD5 is activated (high active, VCC +5 Volts).


In 16 KB mode 16 Kbyte ROM are inserted at memory area $8000-$BFFF of the Atari. Lines RD4 and RD5 are activated (high active, VCC +5 Volts).


Programming with the AtariMax USB Cartridge Programmer currently is only possible in 8 KB mode. Obviously the current version 1.0 of "MaxFlash Studio" already recognizes the 16 KB mode, but errors appear. Technically it is not a problem program  1 Mbyte of equipped memory (two FLASH ROMs with 512Kbyte each) which shall be used in 16 KB mode even with the AtariMax cartridge programmer. Therefore just switch the MEGAMX cartridge to 8 KB mode, flash the datafile which is 1 Mbyte in size and switch the MEGAMAX cartridge back to 16 KB mode - that's it.



What else is possible?


As some of you saw at the Fujiama 2010 there is also third party software for the MEGAMAX cartridge. Jürgen (tfhh in ABBUC forums) will - with high probability exactly to the "ABBUC JHV 2010" - release the "MEGAMAX Cartridge Construction Kit". With that software every owner of a MEGAMAX cartridge can compile his own cartridge. The MEGAMAX Cartridge Construction Kit supports the 16 KB mode exclusively. Menus can be customized and bonusses like own fonts, colorful scrolling and completely keyboard/joystick driven operation are not missing.

A preview version of the menu (in 16 KB mode with a 2MB EPROM equipped cartridge) already exists:






The MEGAMAX Cartridge Construction Kit will be freeware. It can write directly on an inserted MEGAMAX cartridge using SRAM or Flash-ROM and building an own cartridge is also possible step-by-step. Even if it is a little bit unhandily it is possible to write the MEGAMAX cartridge with genuine Atari hardware and its restrictions (e.g. maximum of 180KB on a 1050 disk drive). But the MEGAMAX Cartridge Construction Kit is also able to just create data files for an EPROM which can be burned then - so there are a lot of possibilities.


 The Cartridge


The Look matters, too. Therefore the MEGAMAX cartridge will come in an appealing metal housing made of anodized aluminum. Currently the following colors are available:


-  blue

- black

- green

- silver

- gold

- red

- orange

- gray


There are different LEDs and buttons:


LED RD4 – indicates that area $8000-$9000 is inserted (16 KB mode)

LED RD5 – indicates that area $A000-$BFFF is inserted (8 KB and 16 KB mode)


Those two LEDs indicate is the cartridge is active by software. If they do not light but the cartridge is switched on ("ON" lights up, see below) bank switching was deactivated by access to $D580-$D5FF. The state of these LEDs has nothing to do with the MEGAMAX cartridge itself being switched on or not and only serves for meanings of control and testing.


Button „RESET“: Pressing it sets the MEGAMAX cartridge back to bank 0.


Button „16K“: Button pressed: 16 KB Modus active


A blue LED next to the button "16K" lights, if 16 KB mode was chosen. If the button is not pressed and the LED is off, 8 KB mode is active.


Button „WP“: Button pressed: SRAM/Flash-ROM write enabled


A red LED left of the button "WP" lights up, when write protect mode is switched OFF. With the button pressed and the LED lighting up writing to SRAM or Flash-ROMs is possible. If the button is not pressed and the LED is off, write access to the memory is disabled.


Button "ON": Button pressed shows that the MEGAMAX cartridge is switched on and the green LED lights up.



The pricing for the MEGAMAX cartridge is the following:


1 MEGAMAX cartridge equipped with 2x 512 Kbyte Flash-ROM: EUR 49,-


1 MEGAMAX cartridge equipped with 2x 512 Kbyte SRAM: EUR 59,-


1 MEGAMAX cartridge equipped with  2x 27C080/27C801 EPROMs: EUR 59,-


1 MEGAMAX cartridge equipped with  1x 27C080 EPROM: EUR 54,-



This is what you get additionally:


The schematics,

the GAL listings

and the software!


The AtariMax Studio Software can be downloaded here or  here..




Orders are open now!

To order send an EMAIL with subject „MEGAMAX MODUL“ to mega-hz at


Many thanks for their great support to TFHH and HIAS who helped with hints and improvement suggestions and never ending Beta test!


















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