We’re not exactly sure how old [SnailMail] is, but he’s probably a member of Generation Alpha considering that to our wizened eyes the lad looks only slightly older than a fetus– which makes it all the more impressive that he’s written his own text editor, from scratch, in C– on a 386. See, [SnailMail] tried to learn the modern way, with IDEs that have code completion and AI integration, but his thoughts couldn’t gel in the modern environment. So he went online and bought an old IBM-compatible complete with monochrome amber monitor, and a whole 4MB of RAM. Big spender that he is, [SnailMail] upgraded that to 8MB.

Rather than fall victim to the siren song of Wolfenstien 3D or SimCity, he set out to learn to code: C, specifically, since that language bridges four decades between [SnailMail] and his new PC. Even more specifically, he got ahold of disks for Borland Turbo C and Turbo C++, which brings back memories for some of us. Of course the lad also had to learn how to use a DOS PC at the same time, but a teen in the 80s with a fresh box would have climbed the same steep learning curve. Some of you probably remember doing so yourselves. Just like you–or the hypothetical teen in the 80s–[SnailMail] did it not by googling or begging Claude for answers, but by digging into books. Many books.

After all the reading, he started with a text editor, something we remember being a pretty big project not given to first year students. Video evidence suggests he pulled it off. He describes how his solution works from about 8:00 in the video, so you greybeards in the audience can judge his work for yourself.

If you’re a member of Gen Alpha reading this and looking to learn to program, we cannot recommend this technique highly enough– [SnailMail] is going to have a better understanding of the underlying logic of computer science than a lot of CS grads being frocked today. Especially when you consider he ends by promising to learn assembly, something we heartily endorse.

The Intel 80386 is a rather fascinating slice of computer history. It marked the first 32 bit X86 processor, and was a staple of early desktop computing. Like all chips, it has a number of quirks, one of which being the fact that all commands are executed in microcode. By this nature, it was a rather excellent prospect to be re-implemented in an FPGA core called the z386. However, it was lacking a feature native to the original 386, early start memory access. So to bring some performance to the z386 project, [nand2mario] went forth to fully implement this feature for FPGA 80386s.  

Instead of taking a cycle to find and allocate the memory required for executing the next instruction, the 386 would start this in the previous cycle. This is achieved in hardware by nature of having a separate memory management unit. In the FPGA, the key difficulty proved to be in getting the computation fast enough to execute within a single cycle. This change netted an approximate 9% performance benefit. However, for [nand2mario] this was too small a performance uplift. 

Some rewrites of the store cue allowed for cutting a cycle out of the process further improving the performance. However, more performance required slight deviations from the design of the original 386. Because code-branches are performance critical, the z386 project now computes the branch memory jump several cycles earlier than the 386, reducing the cycle time for the jumps from 9.25 to a mere 6. Some final changes to the microcode decode frontend rounded out the optimizations covered in this latest blog post.

The net result is an approximate 39% increase in performance in the all important DOOM benchmark. The z386 still not a complete project, the performance is still lacking compared to the 386, and it remains unable to boot Windows. X86 is complicated, which will take time, so make sure to stay tuned for more coverage! While you wait, make sure to check out our original writeup of the z386 project. 

Pauli Rautakorpi, CC BY 3.0.