In order to create Commando 2084, I had to disassemble Commando. My original intention was to patch what was only needed and stop there. But I got carried away and I ended up analyzing and commenting the entire Commando code.
The commented code (that can be recompiled to generate the exact original binary) is here:
A few months ago I got an Atari 1040 STF. I knew nothing about it when I got it, except that it was a similar to the Amiga.
The Atari ST, the Amiga and the Macintosh were computers released in the mid 80’s, all of them based on the Motorola 68k, and all of them came with a windows-based GUI. This was a revolutionary step compared to the 8-bit machines which were CLI text-driven.
The base “ST” model includes:
8 Mhz Motorola 68000 CPU
Yamaha YM2149 3-voice square-wave plus 1-voice white noise (mono)
Compared with the 8-bit home computers like the C64/C128, the Atari ST is a good improvement. From only 64K/128K RAM to 512K (or 1024K) RAM, an 8 Mhz CPU (vs. 1 or 2 Mhz) and Midi. But there are no hardware sprites (no blitter), and the music is chiptune, like in the C64. The C64 SID chip might be even better. The video modes are OKish. Having a 320×200 @ 16 colors from a palette of 512 is nice, but not that impressive. It is worth noting that the Atari ST (like the Amiga and the Macintosh) don’t have “text video modes”, they only have “graphic” ones.
The demo is divided in the boot loader and demo 3 parts
The demo is intended to work with a 64K RAM (or more) PCjr. Booting from its own boot loader is needed to save precious memory. DOS alone takes ~20K of RAM. That is 30% of the total memory. You don’t want to waste that memory.
The Cromemco System Three is a Z-80 based computer. Which is nice, because I always wanted to learn Z-80 (this is my second Z-80 computer, the other one is a MSX2).
But What I like about the Cromemco is how well-built it is. I love it.
The computer is that not big, but it is a very heavy computer.
At the moment I don’t have the needed cables to test it. If I can’t find them, I might be able to build them myself (or not). If manage to get the cables, and provided that the computer works, I promise to write a game or something for it 🙂
But how fast is an IBM PC 5150 compared to a PCjr ? or to a Tandy 1000? or how fast is the Tandy 1000 HX in fast mode (7.16Mhz) compared to the slow mode (4.77Mhz) ? Or how fast is a nop compared to a cwd ?
I created a test (perf.asm) that measures the performance of different opcodes and run it on different Intel 8088 machines. I run the test multiple times just to make sure the results were stable enough. All interrupts were disabled, except the Timer (of course). And on the PCjr the NMI is disabled as well.