These are a number of notes gathering information.

Current status

Ideally

The current target is to simplify the emulator with the ultimate goal to rewrite it either in common lisp, Nim, Go or Julia. Nim is currently the most tempting candidate after seeing the impressively small size of Nimes NES emulator binary: sub 300k when the Go version on which it is based is around 11M. In the meantime, the pure C emulator might be looked into.

Currently, the clang compiler is used.

In the meantime, simplification/changes are ongoing with an ongoing integration test of merely compiling the genera runtime (i.e.not even running it - just successful compile).

Only 2 compile targets: genera (the current one) via the old makefile and genera_c, the C emulator via cmake. No iVerify or Minima. Only one platform: Linux. No FreeBSD, Darwin or MacOSF since I have no access to them. In due time, if Nim/Go/Julia work, FreeBSD and Darwin should be easier to port into.

The last commit at which Brad's version still compiles is https://github.com/Manny8888/vlm/commit/da42b63bdc4eb1b18f816f7fbb93bccef0f8b028

After that, changes are targeted to making the c-emulator compile with no attention whatsoever paid to that version.
Last version got the c-emulator compile, although NO VERSION HAS BEEN CHECKED THAT THE EMULATOR ACTUALLY RUNS!
Having a much reduced code base which is more understandable than Alpha assembly leaves me free to move to the next step: rewrite in Nim in another repo.

Current environment

What do I use:

Spacemacs + slime + SBCL for the lisp development
VSCode or KDevelop for the C development
VSCode for Nim
cmake is used in VSCode to build the c-emulator (add the relevant cmake extensions in VSCode if desired)

How to run:

Step 1: recreate the C files from the ALPHA assembly

From an SBCL prompt:

load/compile stub/convert-asm-to-c.lisp WARNING: output4.c had to be patched following the supplied diff file. Checked this is OK!
go into: (in-package :alpha-axp-internals)
run: (build)

Step 2: compile the Genera runtime

Ensure the following is available: usual build packages, clang, libpcap-dev

In the top directory:

make clean
make genera

Cross fingers...

Alternative Step 2: compile the Genera_c runtime

Ensure the following is available: usual build packages, clang, libpcap-dev, cmake, ninja Click the VSCode build button...

Structure of the emulator

The emulator is split into 3 parts:

the "life support" that emulates the hardware environment (console, FEP, disks, network)
the emulator proper which emulates everything but the CPU
the CPU

Life support

The life support is common to all emulators and is coded in C.

It grew out of the Mac Ivory environment where the life support package was software available on the Mac to interface with the Ivory add-on hardware card providing the Lisp Machine.

In the Genera version, the emulator replaces the physical add-on card, the purpose of life support remains the same.

Emulator

The emulator comes in different flavours: Alpha assembly, C version started but unfinished by Symbolics, C version by Brian PARKER. The Alpha version is written in lisp (the assembly) instructions are lisp functions/macros) that is then assembled by a lisp assembler. The Brian P. C version basically takes the Alpha version and assembles it into C instructions (instead of generating Alpha binary).

The CPU is provided by the Aplha assembly, the Alpha assembly compiled to C, or the C emulator (emulator.c).

Build system

.sid files

No idea where .sid files come from.

They are manipulated by assembler/alphadsdl.lisp (Does DSDL mean Document Schema Definition Language?). As best as I can see, DSDL is a LM facility that describes a file type and methods to convert it into other file types. Here, the .sid files are converted into .as (Alpha assembly), .c, .h and .lisp files.

Note that I have completely ignored the Power G5 version.

BP Emulator

(BP = Brian PARKER)

stub/process.lisp: converts Alpha ISA into C statements, then converts assembly (written in lisp) files to c files. It has been renamed convert-asm-to-c.lisp.

Various notes

The assembly file describe the instructions as list of symbols. Each item in a list must be a symbol; therefore no item must be evaluated past read time. This explains why many values are prefixed with the '#.' reader macro which forces a read-time evaluation (see http://www.lispworks.com/documentation/HyperSpec/Body/02_dh.htm). (Not entirely sure that this is a correct explanation, but the point remains.)

Far example fcallmac.lisp line 42: #.1_22 forces the read-time evaluation of 1_22 which is a constant defined as 2^22.

Manny8888/vlm