Jonathan Cauldwell releases a custom ROM for the ZX Spectrum with built-in Arcade Game Designer (AGD)!

Jonathan Cauldwell, the father of the Arcade Game Designer and the Multi-Platform Arcade Game Designer, wrote me this morning to tell me he has just released a custom ZX Spectrum ROM that runs AGD, freeing up the entire Spectrum RAM for users’ games. Because of that, games can naturally be much bigger than before.

The new ROM is written from scratch, and since AGD is built-in now, some compromises had to be made to make everything fit in 16K, but the necessary functionality is present. While re-writing the ROM, Jonathan also improved keyboard handling. The new routine can now detect a new keypress before the previous one is released, allowing fast typing, unlike the original Speccy ROM.

One of the pet peeves of the regular AGD is that when you have a code error, you are on your own to find where the error is. While this ROM-based AGD still doesn’t have enough space for a proper syntax checking feature, it makes bug hunting a thousand times easier. When the script code has an error, AGD will now move the cursor to the line where the error was found!

The ROM can be used in a real ZX Spectrum, if you have the ability to burn a new one, or can easily be used in emulators. However, for the latter, you will need to disable any fast tape loader option since the emulators usually patch the original ROM to trap the save and load routines to implement the fast loader. This is necessary because AGD ROM relocated the tape routines, and the emulators won’t be able to find them anymore. Cauldwell adds that any emulator developer that wants to support AGD out-of-the-box can contact him, and he will inform where are the new addresses for SAVE and LOAD.

Because you will be working on real-life loading times, it is recommended that, while developing, you save your game using the emulator’s snapshot feature. After the game is ready for the masses, you should export the binary directly from RAM addresses 24832 to 65535.

The new AGD ROM is available free of charge following the link below. Of course, you are always welcome to name your own price as a token of appreciation for Jonathan’s hard work to bring more retro games to our lives!

UPDATE: The ZIP file contains the ROM using the .BIN extension. Some emulators will not let you load it unless you rename it to .ROM. I did that and it works just fine.

The ROM can be downloaded for free from here:

Author: Paulo Garcia

5 thoughts on “Jonathan Cauldwell releases a custom ROM for the ZX Spectrum with built-in Arcade Game Designer (AGD)!

  1. Good question! I was going to mention but I forgot. You can just rename it to .rom and load it in the emulators’ configuration,

  2. I’ve tested the ROM on with real ZX Spectrum hardware using my fairly new ZX ROM hardware, no issues, and the machine starts straight up into AGD! (I put some pics on my Twitter: @QuazarSamCoupe)

    I became fascinated with the failed ZX ROM cartridges from 1983/4 last year and over the last 12 months released a new ZX ROM Interface for the ZX Spectrum, that works on all models: 16k,48k,+,+2,+3,+2A/B and the new ZX Spectrum Next. To accompany it I’ve also released a programmable flash cartridge which stores 16 ZX ROM cartridge images or system ROMs. I also produced an interface allow the ZX ROM cartridges to run on the SAM Coupe – ZX-ECUTOR. Info:

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