Purchase a Monkey Wrench II Cartridge for BASIC Programming on your Atari 800 Computer (10-15 mins)

Task: Purchase a Monkey Wrench II Cartridge for BASIC Programming on your Atari 800 Computer (10-15 mins)

Needed: Web browser, Atari 800, Atari BASIC cartridge

Time: 10-15 minutes


I learned to program in BASIC on my Atari 400 and then 800 computers. I started with Atari BASIC and later BASIC XL. Atari BASIC was of course quite limited and didn’t have any macro functions to make it easier to work with long programs. The Monkey Wrench and The Monkey Wrench II augmented Atari BASIC by adding a bunch of useful commands such as renumbering the lines, scrolling through your code, and a machine language monitor. Interestingly, the Monkey Wrench cartridges took advantage of the right cartridge slot with Atari BASIC in the left slot. These were among a short list of cartridges released for the right slot. I previously wrote about Magic Dump II that also fits in the right slot. The cartridge used 8K of memory leaving the 48K stock Atari 800 with 32K for BASIC and programs.

Monkey Wrench was developed and released by Eastern House Software. Here is a link to their software catalog from 1983. They also marketed an EPROM board for loading your own software.

Monkey Wrench II in Right Slot
Monkey Wrench II in Right Slot


First, purchase a Monkey Wrench II cartridge from eBay or another source. Version II is much easier to find that the first one. These are somewhat rare and thus fetch about $75 to $100 each on eBay. I paid $75 for mine. There were four listed in this price range at the time of this post.

Second, you can read the instruction manual here.

Third, you will need an Atari 800 to use it. Plug Atari BASIC into the left slot and Monkey Wrench into the right slot. Power on. You should see the READY prompt followed by text that says The Monkey Wrench II followed by the copyright and the name of the published.

Fourth, a simple test is to type in a short program such as 10 PRINT “MONKEY WRENCH” and 20 GOTO 10. You can renumber the lines using the command >R 1 1. This will convert lines 10 and 20 to 1 and 2. You can also start the monitor with >* as shown in the photo below. This will display the 6502 CPU registers.

Monkey Wrench II
Monkey Wrench II Monitor


I recall owning and using this cartridge back in the day. Sadly, I seem to have lost it along the way and had to buy a new one.

I am not sure how much one would use this tool today as many choose to program on a modern computer before trying on original hardware. Owning a Monkey Wrench cartridge might be of more interest to collectors.

Not sure I have ever seen one of these in original packaging on eBay…