65XE Cart

[coin-op]

Hi All

 

I want to write some software (utility not game) that will run from a cartridge on the Atari 65XE. This is a fun project for myself as I have written the same software on the Windows platform and as part of an embedded project before.

 

What I need are just a few pointers from the more savvy 8-bit guys out there if you don't mind.

 

I have seen the PCB (though I may etch my own if there is a schematic available), EPROM and passive(s) that I need in order to make the cart in the store here so thats not the problem. I want to know the specifics of what format the compiled program needs to be in when it is blown onto the EPROM (straight .bin file?). I will be writing the software using Atari BASIC on my 65XE.

 

That will get me going for now and thanks in advance.

[Wrathchild]

Hi,

 

This will depend on the size of the application's binary.

If less than 8K or 16K then this can fit on a standard

board and fill the upper memory, leaving the lower memory

free for workspace/variables/screen memory etc.

 

If its just for a 64K Xl/XE machine then code or data can be

tucked under the Operating system.

 

If your code is larger then you have to consider bank switching.

Here you can then move blocks of code/data out of the cart area

and relocate it to RAM. Getting a bit more clever, the code can be

arrange in banks and accessed/called upon when required.

 

However, if you are compiling a BASIC program then you most

likely won't have the control over the layout or code/data etc.

Because of that the best thing would be that the whole app is

relocated out of the cart's ROM and into RAM. If you go for a

switchable cart model then after everything is unloaded, you

can turn the cart off - freeing the CART memory area as RAM.

 

The FlashCart would be ideal for that as, if you have a programmer,

you can reflash the EEPROM easily during development.

 

Regards,

Mark

[coin-op]

Are there any internet resourses or threads on this forum that concern with writing software for use on a cart? My frst version of the software will only be ~8k so all hopefully will be fairly straight forward! (famous last words).

 

Also, where can I buy a flash cart?

 

TIA

Edited October 26, 2006 by coin-op

[Wrathchild]

FlashCart details here:

http://www.atarimax.com/flashcart/documentation/

and forums to chat about these at:

http://www.atarimax.com/flashcart/forum/

Though you can use the programming thread on AtariAge too:

http://www.atariage.com/forums/index.php?showforum=51

 

Also, SunMark stock some boards:

http://www.sunmark.com/ (scroll down)

 

There is a comparison of different cart models here:

http://www.atariage.com/forums/index.php?showtopic=69425

[coin-op]

Thanks for the links. I appreciate it.

[Wrathchild]

Your welcome. I'd recently got a 28-pin DIP to 32-pin PLCC adaptor from Ebay and took a "Fight Night" cart and had the chip replaced with the adaptor. Sadly the one's on Ebay are for a 29C256, wheras the Atari cart chips were 23Cxxx based. So this doesn't work as the pin mappings to the Am29F010 chip I wanted to use don't tie up and its not worth trying to hack the adaptor to do so.

 

On the cards is though having a board layed out for me using the XEGS-Switchable model but using a 29F010 PLCC instead of a 27C010 (or 256/512). But real-life work tends to be getting in way a-lot of late

 

As it stands only Nir Dary builds these by hand, so having a small run of these done would be useful, though using a FlashCart is often just as straightforward. The thing I like about the XEGS is the idea of having the fixed 8K bank as a 'controlling' area, e.g. with all your most often used routines or jump tables to access routines in the required bank which is switched in appropriately. E.g. your VBI music routine could be in the fixed bank and your music data and FX in another bank and switched in as required. So your VBI code (in RAM) could switch on the ROM, call the player, then switch off the ROM, and the CART memory area is still yours to use, e.g. for game state data/level data not required during the VBI.

Edited October 27, 2006 by Wrathchild