larsonmars / sysvars

Setup environment variables that hold system Information to be used for a multi-system startup-sequence

Overview

sysvars is a small CLI tool for the Amiga that creates several environment variables holding valuable system information. These variables can be used, for example, in the startup-sequence to enable/disable certain patches, assigns, and so on.

Currently, the following variables are set:

• $CPU: installed CPU, for example 68030¹
• $FPU: installed FPU, one of 68881, 68882², internal² (for non-LC/EC 040 and 060 CPUs), or empty if no FPU is available
• $Chipset: installed graphics chipset, one of OCS, ECS, AGA³
• $VFreq: the vertical frequency of the native display, can be either 50 (PAL 50Hz) or 60 (NTSC 60Hz)
• $KickVer & $KickRev: Kickstart version and revision ⁴
• $BSDSockLib, $BSDSockLibVer, and $BSDSockLibRev: The id, version and revision of bsdsocket.library available, empty if bsdsocket.library is not available
• $UAEMajor, $UAEMinor, $UAERev: The version of UAE detected, empty if UAE was not detected⁵

Requirements

The tool works best with Amiga OS 2.0 or later. Here, it calls SetVar, which allows for local scope variables. Local scope is no limitation, because the workbench is also loaded in the scope of the startup-sequence. Another advantage is that it does not require ENV:. This means it can run very early, even before SetPatch.

However, for the purists, sysvars runs happily also on OS 1.3 and even down to OS 1.1. However, there are some limitations to consider

• In OS 1.3 and below, sysvars will currently detect CPUs above 68020 as 68020 and any FPUs as 68881.
• in OS 1.3, environment variables can only have global scope (i.e., they reside in ENV:). This means you must have ENV: mounted (e.g., to some folder on RAM:). This is not required for OS 2.0 and above.
• In OS 1.3, environment variables are not useable with every command, but only with IF. Thus, things like ECHO $CPU do not work. You must use something like IF $CPU GE 68010.
• Below OS 1.3, UAE detection does not work
• Below OS 1.3, the IF command does not support environment variables. You must use the IF command from Workbench 1.3. Also, only EQ (equal) seems to work here.

Installing

1. Copy sysvars to your hard or floppy disk drive (e.g., in the c directory)
2. Add it to your startup-sequence or User-Startup
   • For OS 2.0 or greater there is no issue to call sysvars very early, even before SetPatch
   • For OS 1.3 and OS 1.2, you must ensure that ENV: exists prior running sysvars (see previous section)

Building

The source should build with VASM, AsmOne, AsmTwo, and AsmPro.

You can also compile this in VSCode using a nice VSCode plugin, a suitable configuration is included in the .vscode directory.

Testing

There is a filesystem structure in test/echo-test that can be used for testing in vscode (virtual filesystem) or on a bootable floppy/partition on a real Amiga. There is a small script CreateTestDisk that creates such a bootable disk. The test can also be executed from Workbench (via IconX).

To make it also work with KS 1.2 and 1.3, some files from Workbench1.3 are required, which I cannot distribute. If you need this, just insert your Workbench1.3 disk and start the script Add OS 1.3 Support. Note that Workbench prior 1.3 cannot be used, due to the lack of support for environment variables.

Why such a Tool?

As many Amiga users, I have multiple Amigas, booting from flash memory. However, I do not want to maintain multiple operating system configurations. In the past, I have used several tools to branch during startup, which yielded a complex startup-sequence/user-startup and an extended boot time.

I wanted a small fast utility that gives me neat environment variables, so I can write something like this in the startup-sequence:

IF $CPU GE 68020
  MCP
ENDIF

or

IF $FPU EQ internal
  FastIEEE
ENDIF

Also, I always wanted to learn M68k assembler. After 30 years using an Amiga this was about time!

Future Plans/Known Bugs

The tool is already quite useable, but there are still some things missing, which I want to fix in future versions (no particular order):

• Add memory-related variables, such as $Chipmem, $Fastmem, and $Slowmem (especially to distinguish Amiga 5000 trapdoor/slow memory from actual Z2/Z3 Fast memory)
• Add $RTG variable to enable/disable stuff like FBlit or swap screen mode configurations
• For Os 1.3: add detection for CPUs > 68020 and at least the 68882
• Make use of boards.library and identify.library if available for even more expansions.
• Make a WinUAE/FS-UAE-based test suite for automated tests (CI/CD-like)

Footnotes

1. On OS 1.3 and below, CPUs > 68020 are currently detected as 68020. 68080 (Vampire) detection is implemented following http://adevnoo.wikidot.com/detect-080-code ↩

2. On OS 1.3 and below, all FPUs are detected as 68881. ↩ ↩²

3. Since version 0.12, SAGA (Vampire) detection is implemented following http://adevnoo.wikidot.com/detect-080-code ↩

4. Workbench 2.0 and above ↩

5. UAE is detected via the uae.resource, which is only there if a virtual hard drive or another UAE expansion to be enabled. Thus, detection will fail on floppy-only-unexpanded Amiga configurations. ↩