Altirra and XEGS emulation

[Atari Nut]

I'm trying to get the XE Game System emulation to run Missile Command.  I have the Rev 4 bios which is recognized by Altirra but the emulator just starts to Basic with a warm reset or the Self Test with a cold reset.  Shouldn't Missile Command launch if a cartridge is not attached?

[+Cafeman]

Are you using the real BIOS rom for the XEGS, or the default one pre-loaded into Altirra? I wonder if that is why.  The ROMs are usually named ATARIOSB.ROM or ATARIXL.ROM. 

 

(I'm just guessing but would also like to know the solution here). 

[+Cafeman]

Here is the help file from Altirra about XEGS - see ROM and Missile Command notes: 

 

Altirra Help

The XE Game System (XEGS)

Description

The XE Game System, or XEGS, is a mildly adapted version of the 800XL computer intended to double both as a game console and a computer. It is much more similar to the computer line than the 5200 and the vast majority of software that runs on an 800XL will also run on the XEGS.

Configuration

The XEGS is very similar internally to the 800XL: 64K of RAM, 16K OS ROM with built-in self test, 8K internal BASIC ROM, and the same ANTIC/GTIA/POKEY/PIA chips. It also takes the same cartridges and has a serial I/O bus connection for disk drives and other SIO peripherals. Thus, it can run the same cartridge programs, BASIC programs, DOS, etc.

There are a couple of minor hardware additions. The keyboard is detachable and optional on the XEGS, and software can detect if the keyboard is attached. The XEGS also has an additional 8K internal game ROM containing Missile Command, which activates if the keyboard is detached or SELECT is pressed. The OS ROM is also slightly revised over the XL/XE line, with a newer version 4 OS that contains support for booting without the keyboard.

Emulation-specific concerns

Emulating the XEGS in Altirra is nearly the same as emulating an 800XL. By default, the XEGS profile has its own hardware and firmware settings, but the majority of settings are shared with the rest of the computer line.

The keyboard can be "detached" or "attached" in System > Console Switches > Keyboard Present (XEGS). For this to work, the version 4 OS must be used, sometimes called atarixegs.rom. The common version 2 OS ("atarixl.rom") can be used if the version 4 OS is not available, but detached operation and Missile Command will not activate.

The version of Missile Command that ships with the XEGS is modified to work with the XEGS's version 4 OS. Some older versions of Missile Command were hardcoded to the 800's OS and will break if run on the XEGS; the symptom of a version mismatch is that game's keyboard controls won't work and the level parameters can't be changed.

[Atari Nut]

Hi Cafeman.  I do have the correct Atari ROMs.  Altirra recognizes them and they are listed in the Firmware Manager in addition to the Altirra built-in ones.  Thanks for the info and the section from the Help file.  I see that I need to detach the keyboard in System > Console Switches > Keyboard Present (XEGS) and add a ROM in Firmware Manager to XEGS Game ROM.  If I do this, it works!  If I wanted to keep the keyboard attached, how do I boot with the Select key pressed?

[bfollowell]

9 hours ago, Atari Nut said:

If I wanted to keep the keyboard attached, how do I boot with the Select key pressed?

 

I haven't tried this myself, but I'm assuming you'd boot the emulator while holding down the appropriate key that corresponds to the Select key in the emulator.

 

Edited December 30, 2020 by bfollowell

[Atari Nut]

Tried that...it doesn't work.

[scotty]

I have no problem running Missile Command when I disable the keyboard.  Works great.