# Acorn ARM Second Processor

BeebEm emulates the Acorn ARM Second Processor board, also known as the ARM Evaluation System. The ARM interpreter and disassembler code is based on the Tarmac software written by David Sharp to whom we are grateful for allowing us to use it with BeebEm.

The Acorn ARM Second Processor was an 8MHz system running with 4MB RAM on an ARM 1 RISC processor.

You start the Acorn ARM by selecting ARM Second Processor on the Hardware → Second Processor menu. The ARM Second Processor has no operating system but relies on a sideways ROM to provide a command line prompt to the user.

Once you see the A* prompt, type *HELP SUPERVISOR to see what in-built commands are available.

The ARM Evaluation System came with 6 discs full of software. Disc 3 is included in the DiscIms folder which contains ARM Basic. Load the armdisc3.adl disc image (ensuring you are in ADFS mode), type *MOUNT 4 and *AB to load ARM Basic. Type HELP . to list all BASIC commands.

The remaining disc images plus a hard disc image containing all 6 disc images can be downloaded from Jon Welch's website: Acorn ARM Discs.

These discs contain the Acorn ARM application software including:

- TWIN - Editor
- ARM Assembler/Linker/Debugger
- ARM Basic
- Lisp
- Prolog
- Fortran 77
- General File Utilities

You will also find some manuals for the ARM Second Processor on Jon's site as well. If you have any manuals or other disc images that Jon does not have feel free to send them to Jon to add to the library.

To use the hard disc image:

- While BeebEm is not running, download the hard disc image and copy the file scsi1.dat to your DiscIms folder.
- Start BeebEm.
- Type CONFIGURE TUBE to use the ARM co-processor by default.
- Type CONFIGURE FILE 13 to make ADFS the default filing system (so you can read the disc image).
- Type CONFIGURE MODE 0 to switch to a screen mode with smaller font.
- Press `Ctrl` + `F12` to reset the machine so configuration changes take effect (presses `Ctrl` + `Break` in the emulator).
- Type MOUNT 1 to mount the hard disc image as drive 1.

To make sure all your settings are saved for next time so you don't have to repeat the process, select the Options → Save Preferences menu item.