S/XEGS RAMCART 128KB by C.P.U.

Radek Štěrba (Raster) & Robert Petružela (Bob!k)

This Atari XE/XL cartridge made by raster & bob!k / c.p.u. makes possible to load, keep and run most of existing Atari XE/XL cartridge games or other special software. It has memory 128 KB SRAM powered by Atari computer or by one small 3V battery when the computer is turned off.

General description - version "G1.04 FIX3+"

• 128 KB SRAM with 3V battery - years of lifetime, unlimited number of overwriting, no block-save necessity.
• Full XEGS cartridge bank switching compatibility. All the great 32/64/128KB XEGS cartridge games is possible to play on Atari with this one RAMcart (without need of ANY modifications).
• Usable for standard 16KB cartridge games, also most of classic 8KB cartridge games are working.
• SXEGS switchable mode.
• Read only mode for cart memory protection.
• XEGS RAMcart File Feeder Atari software for easy loading of cart dump files.
• With special Atari DOS it can works also as ramdisk (D8: device with cca 120KB, battery keeps its content).
• CreaXin1 PC software for easy making of programs/games packages.
• Components' price cca 250 Kc (8 EUR).

Bank switching

This cartridge uses bank switching with 16x8KB banks in two memory locations. Lower area $8000-$9fff can map any from 16 banks (0-15) by storing bank number to $d500 ($d5xx), upper area $a000-$bfff has constantly mapped last bank (15). This system is fully compatible with so-called XEGS cartridge bank-switching style, so all the XEGS cartridge games/software is working very well.
If cartridge is in ”SXEGS mode” (switchable XEGS), then there is possible to enable/disable cart via software by bit 7 of stored bank number value (bit 7 is unset => cart is enabled; bit 7 is set => cart is disabled).

Controlling software

For loading of any cartridge ROM dump file, you can use program ”XEGS RAMcart File Feeder” (RFF). It’s easy to use it – you have to specify device and filename, or only device with colon (or you can use *.*, *.ROM, etc.) and press Return for selection from directory listing.
Supported file types are raw cartridge dump files (ROM, BIN), also CAR format with head information (cartridge type) is possible to use.
RFF will recognize size of cartridge (from 8 to 128 KB) automatically and then fill the cartridge memory banks as it’s needed. If some problem occurs, it shows relevant message or it will ask for next action.
Note: We were shortly testing most of available Atari XE/XL cartridge game dump files (all ROM sizes: 8, 16, 32, 64, 128 KB) published on www.atarimania.com site and all of them was working perfectly.

Cartridge controls / indicators

• Enable button
  You can enable RAMcart by pressing this button. (Then you have to press Atari reset key generally.)
• Write / Read only switch
  In write mode, any program can write to cart memory banks area ($8000-$bfff) and modify it. In read only mode, reading from cart memory is allowed only.
• SXEGS / XEGS mode switch
  In XEGS mode program can select bank, but can’t enable/disable cartridge by bit 7 of bank number value. In SXEGS mode cart enabling/disabling by software (bit 7 of bank number value) is allowed. (Note: Manual enable/disable cartridge buttons are working in both modes always.)
• Battery on / off switch
  When cartridge is pushed in Atari computer, cartridge memory is powered by Atari computer. If computer is turned off and cart is pushed out, cart battery makes it. But if you don’t want to keep content of cart memory, you can turn off this switch.
• Disable & Reset button
  You can disable RAMcart by pressing this button. If you will hold down this button and press Atari Reset key simultaneously, Atari OS will perform the cold-start routine. (It can help with some programs, which persists after the Atari reset key.)
• LED diode
  Indication if cart is enabled / disabled.

Sample cartridge game dump files

Note: Classic Atari XE/XL cartridge games are running directly from the cartridges, so RAMcart will be enabled all the time. But following games are cartridge versions of originally no-cartridge games, that is why they need to disable the RAMcart after the game initialisation. In ”SXEGS mode” RAMcart will be disabled automatically. If RAMcart isn’t in ”SXEGS mode”, you will be asked for disable the RAMcart manually (by pressing cart disable button). 
If you want to run game from the RAMcart again, you have to enable RAMcart manually (by pressing cart enable button) and then press the Atari reset key.

• NATURIX.ROM
  Naturix game, by Raster, 1994
   
• MAGN2002.ROM
  Magnetit 2002 game, by Raster, 1993,2002

Special software

SXEGSD2P.COM
This is hastily patched version of DOS II+ by Stefan Dorndorf (freeware / PD software).
After execute SXEGSD2P.COM, DOS is stored into RAMcart memory and you can start it from the cartridge every time. It has default device D8: and this device uses SXEGS RAMcart memory as 120KB ramdisk (cart battery keeps his content when Atari computer is turned off). 
Warnings:

• RAMcart have to be switched to ”SXEGS mode” all along!
• RAMcart have to be in ”Read only mode” every time you will press the Atari Reset key! 
  (DOS and ramdisk data could be destroyed otherwise!)
  There is highly recommended to allow RAMcart ”Write” when you copy/write some data to ramdisk only, and let switch in ”Read only mode” generally.
• If green or yellow color is showed on screen background, it means that there is a problem with software enabling/disabling of RAMcart (green color => enable RAMcart request fail, yellow color => disable RAMcart request fail). Please, check RAMcart switch XEGS/SXEGS mode – it has to be in ”SXEGS mode”.
• If red color is showed on screen background, then there is a problem with writing operation. Please, check if RAMcart ”Write / Read only” switch is in ”Write” mode.
• DOS doesn’t clear the RAMcart memory, so you have to format ramdisk (command FM# at D8: device) before first using of it.

Other cartridge dump files

We recommend the site www.atarimania.com, where you can find a lot of cartridge dump files of classic old Atari games, as well as old great but lesser-known XEGS games, for example Rescue on Fractalus (1987, 64KB, with original game intro), Tower Toppler (1988, 64KB), Commando (1989, 128KB), etc.

Important notes

Two versions of GAL firmware exists, so you can choose which behavior seems to be better for you and use one of them:

1. If you will use firmware "sxegsramcartG104_GAL.jed" :
   Each time you turn on the Atari computer, the RAMcart is enabled by default and started automatically. If RAMcart memory is empty or it doesn’t contain any functional cartridge ROM image, system can crash immediately. In this case you have to disable RAMcart by pressing ”Disable&Reset” button and then press the Atari Reset key.
    
2. If you will use firmware "sxegsramcartG104_GAL_defaultdisabled.jed" :
   Each time you turn on the Atari computer, the RAMcart is disabled by default. If you want to activate RAMcart, you have to enable RAMcart by pressing ”Enable” button and then press the Atari Reset key.

Every time when RAMcart is enabled and "write" switch is turned on, you have to avoid pressing the Atari Reset key and/or turning on Atari computer, because OS ROM initial routines will clear the main part of RAMcart memory in the other way!

Disclaimer

The authors take no responsibility for any damages, which may take place during building and/or using of this hardware and/or software. 
YOU BUILD AND USE IT AT YOUR OWN RISK!

Additional PC software for S/XEGS RAMcart

• Creaxin1 ...Creaxin1 is PC Win9x tool. It makes possible to create package of Atari programs/games, which will be stored in S/XEGS RAMcart.