8088ify

8088ify is an Intel 8080 CP/M 2.2 to Intel 8086 (8088) MS-DOS assembly language translator. This means that 8088ify reads in assembly language written for the Intel 8080 and outputs an equivalent assembly program for the Intel 8086/8088. As many of us home computer users begin transitioning to the IBM PC with its 16-bit Intel 8088 CPU and new IBM PC DOS operating system, we need not bid farewell to our CP/M programs. 8088ify is the tool to bring our home computing out of the 1970s and into the 1980s and beyond. No need to depend upon expensive and unreliable 8080 emulators!

8088ify was written for PCjam 2021.

We're famous!

8088ify has been featured on Hacker News and Hackaday. We are even mentioned on Wikipedia.

Thanks to everyone for sharing this project.

Why?

I could not find an open source translator between Intel 8080 and Intel 8086/8088. The 8080 and 8088 CPUs were contemporaries from the introduction of the 8088 in 1979 to the discontinuation of the 8080 in 1990. Not being able to easily find such a translation tool surprised me.

It may be lesser-known that Intel had the porting of 8080 assembly code to 8086/8088 in mind when designing the 8086/8088. According to this retrocomputing forum post, Intel even produced documentation of conversion tables between the 8080 and the 8086/8088. Unfortunately, I was unable to find that document. However, there was a commercial tool written by Digital Research, Inc., XLT86, that could translate from 8080 to 8086/8088 assembly. XLT86 was designed for translation from CP/M-80 to CP/M-86 and related DRI operating systems. The XLT86 users manual, which contains DRI's own 8080 to 8086/8088 conversion tables, is available, and which I used for 8088ify.

Later, @bilegeek altered me to an official Intel document for Intel's own 8080 to 8086 translator program.

Building

Run your C compiler on 8088ify.c. It is a single-file C utility and written in ANSI C. As 8088ify was written on OpenBSD, I can verify that it works equally as well on Unix as MS-DOS. It even runs on CP/M and Windows!

8088ify should compile with any ANSI C compiler that includes a strtol() function. I may remedy this in the future with a built-in strtol() function, but as Open Watcom v2 has the function, I have not (yet) found a need.

8088ify can be compiled as a standalone application for Unix, as a standalone application for Windows using the Digital Mars C/C++ Compiler, natively compiled on MS-DOS using Open Watcom v2, cross compiled on Unix for MS-DOS using the Amsterdam Compiler Kit, or cross compiled on Unix for CP/M using the Amsterdam Compiler Kit.

When compiling for Unix, the following compiler invocation is recomended:

$ cc -O2 -pipe -o 8088ify 8088ify.c

When compiling for Windows, the following compiler invocation is recommended:

> dmc 8088ify.c -o

When compiling for MS-DOS with Open Watcom v2, the following compiler invocation is recommended:

> wcl -0 -ox -mt 8088ify.c

When compiling for MS-DOS with the Amsterdam Compiler Kit, the following compiler invocation is recommended:

$ ack -mmsdos86 -O2 -o 8088ify.com 8088ify.c

When compiling for CP/M with the Amsterdam Compiler Kit, the following compiler invocation is recommended:

$ ack -mcpm -O2 -o 8088ify.com 8088ify.c

The included Makefile is for creating a Unix binary, sorry.

Running

usage: 8088ify infile.asm outfile.asm

So long as your system is able to open the input and output files, 8088ify will not fail. That is to say, it is only a mechanical translator. 8088ify does not perform any semantic or syntactic analysis; it assumes the input assembly is valid. The user should review the output before attempting assembly.

Assembling translated programs

8088ify targets nasm. It has been a long time since nasm built 16-bit DOS binaries. In this repository you will find binaries of nasm 0.98.31, as found on Sourceforge, which do work on an 8086 (tested via DOSBox-X).

To create binaries, the following nasm command can be used:

nasm -f bin -o prog.com prog.asm

Where prog.asm is the name of your assembly program output from 8088ify and prog.com is the name you want for your final binary. This also means that all programs translated by 8088ify target the tiny memory model only. This could be improved in the future.

NOTE: This version of nasm is licensed under the LGPLv2.1+. You can find a copy of the LGPLv2.1 license here. This license does not affect the license of 8088ify.

Examples

In the examples directory you will find two example programs: hello.asm which is a typical hello world program and TST8080.ASM which tests all the opcodes of the 8080 to ensure correct functionality.

To demonstrate 8088ify, there are two additional example programs: test1.asm and test2.asm. The test1.asm file is the result of running TST8080.ASM through 8088ify. The test2.asm file is the result of fixing all the nasm errors reported on test1.asm. A diff between the two files can be found in test.diff.

Caveats

8088ify assumes no single line of input assembly code will exceed 255 characters. It will truncate lines longer than 255 characters, but still output assembly for what it did read in before truncation.

Comments are carried over to the output assembly. They may not make sense for an 8086/8088 CPU.

An attempt is made to detect calls to the CP/M BDOS: call 0005h. The first equ statement to assign the value 5 to a label will be assumed to be the BDOS label and used for all call and jmp checks.

Calls to 0000h are also special-cased and will result in an MS-DOS termination call. As with 0005h, the first equ statement to assign the value 0 to a label will be assumed to be the warm reboot label and used for all call and jmp checks.

Line separation with ! is detected but not properly used. Split those lines before running 8088ify.

No macro facilities. Preprocess your assembly before running it through 8088ify.

I don't actually know if 8088ify or the programs it generates will work on the original IBM PC DOS. But I didn't want to ruin the anachronistic sales pitch at the top of this file. 8088ify was tested on DOSBox-X with the 8086 core. Both it and the programs it generates work with the 8086 core.

Not all programs can be mechanically translated and just work. There exists fundamental differences between 8080 and 8086 assembly that need to be smoothed over by hand if such incompatibilties exist in the original 8080 assembly.

If you see the following warning from nasm: warning: uninitialized space declared in .text section: zeroing everything is fine. This is in fact the desired behavior. Newer versions of nasm have a command line option to disable this warning but the older 16-bit versions of nasm do not.

Bugs

None! As far as I know...

If you find one, please open an Issue or (better!) a Pull Request with a diff.

License

ISC License. See LICENSE for details.

Releases

The current release is 8088ify-1.2; a tarball can be found in the Releases section.