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I remember not having any idea what to do in this game as a kid. Granted, I had no clue what an RPG was at the time.

I love how simple COM format is.

Programming languages were incomprehensible, then I saw Assembly. It's the only one that makes sense to me.

I am currently playing this on my handheld. I janked the controls to Dpad being up and down and the buttons diagonal movement. So fun

No mention of how DOS keeps track of blocks of RAM - there is a 16-byte area in front of each allocated chunk, with links forward and backward to the next and previous allocations. Being in real mode, any program can follow these links and work out what else is going on in the machine.

2024… Starfield stole their ship control design from this game. Take that algorithm

I dunno what the fuk your talking about minabytes that is a modern term so your video is all wrong and stupid

A wise man once said: "640 kB or memory should be enough for everybody!" A wise man said: "I'll be glad to accept the invitation to your island Mr. Epst**n!"

I remember playing this Shareware on a Demo disk, "250 Dos games," when I was a kid. This was one of the first computer games I played on Windows 95 back in 1996.

I had to make a DOS emulator a while back the DPMI system (INT 31h) I found pretty interesting.

I like the mod music in the background.

I'm a university student, who struggle to learn this topic, and this video was extremely helpful. thank you very much for putting so much effort into it!!!

@2:02 I swear it sounds like you're saying 'meba byte'.

mebibyte ??? 👎👎👎 perhaps somehow correct, but well, this crazy wording was invented for people who cannot get their mind around that 1kb are 1024 bytes and not 1000 bytes

You made all that sound quite straight forward and approachable which is saying something when you're introducing assembly!

I want to write an OS that sits atop MS-DOS that runs on ELF, similar to how Windows 3 uses NE. Lol.

Your content is super accurate. But are you using voice changers or robotic voice - it is so boring to listen to it - so many times turned off the video.

You keep talking in past tense but they are megabytes if you are speaking in past tense.

You completely forgot to mention unofficial "unreal" mode, where you first switch the CPU to protected mode, extend the segments to 4GB and switch back to real mode. Boom, you can now access full 4GB of RAM from real mode, with real mode DOS, drivers, TSRs, etc. all functioning normally.

When I worked on my first PC, knowing it could have 640k of RAM, it seemed, and it was, an inexhaustible ocean of RAM.

"You are more ugly!"

QEMM

That was great, thank you!

I remember back in the day having a 20MB 386 that was tricked out, and having to have a multiple choice config / autoexec depending on what I needed as I didn't have enough base / umb / himem to get all of the drivers in and be able to run a half decent dos game. one config also had a 16MB ram drive that copied games I would play into it and run the game from ram. it was a long copy time, but games ran fast.

If i remember correctly one can generate COM files with the DOS debugger, too. No need for an assembler 😊

Dr. DOS was VAASTLY superior to CRAP DOS, and EVIL M$ tactics destrpyed it! .....NO FORGIVENESS!!!!!!!! EVIL EVIL EVIL EVIL!!!!!!!!!!!!!!!!!!!!!!!!!

The worm reverse code appears to be: Compare obj-velocity-x with “direction to Jason” (stored in $01) the EOR is a quick way to see if the signs match or not. BPL decides no reverse (bit 7 matches - ie the worm is going towards Jason) Then the reverse code is: Set velocity to F (going right) If vector to Jason (LDX $01) is left, then negate. Store result in obj-velocity-x.

Do you have the commented disassembly posted on GitHub or anything like that? I’d be happy to contribute my own findings. I’m interested in poking through the audio engine and music pattern data.

This is pretty cool! I just got into 8086 - 80486 era and memory management of the 1MB barrier in real mode and protected mode. If only I was more into it when I was younger lol

Best game ever so nostalgic

8:45 "Extended Memory - XMS maps extended RAM to UMBs". What UMBs does XMS use? or does it use conventional memory?

Mebibyte... Ugh.

1:58 you forgot the 186 2:33 the 286 was only mostly compatible, it didn't roll over at the 1MB limit like the 8086/8088 and 186, which is why the A20 gate was needed 3:00 the 386 can run real-mode apps in protected mode using virtual 8086 mode

Is the code published somewhere?

this is a great video, subscribed

This is awesome, I look forward to seeing much more.

The difference between the 8086 and 8088 is that the 8086 has 16 of it's address pins duplexing as data pins, while the 8088 only has 8 of them duplexing as data pins, but they are otherwise identical. This means that the 8086 is capable of accessing it's memory 16-bits at a time instead of 8-bits like the 8088. What I'm curious about is whether or not any motherboards actually implemented this. Given that the 8086 was more popular among business-oriented machines, I'm guessing somebody did, but I'm not familiar with any specifically.

Do you have a GitHub page?

Nobody who used a computer in that time would call a megabyte "mibibyte".

From my experience the memory area above 640 Kb was only available as RAM when a memory manager program like 386MAX or QEMM was installed. DOS 5.0 and higher has a similar memory manager included. Plus you could only do this on a 386 or higher CPU. There were some DOS games that needed this because they needed 600 Kb+ of RAM to run. These memory manager programs also supported the EMS memory interface in software by reserving a 64 Kb UMB area. They also scanned the entire upper memory area to map all free UMB's which included unused areas that were reserved for the system BIOS Typically these programs would load device drivers and TSRs into these recovered UMBs.

the good old days of messing with autoexec.bat and config.sys to to free up memory to maybe run a game

You just have to know your config.sys and autoexec.bat files.

"We'll never need more than 640K " - some guy that was completely wrong.

ms tres

To get Falcon3.0 with expansion packs running.. you needed to know all this shiet in this video - front and back.

The first KB was not occupied by the BIOS. It was RAM and was the BIOS Data Area (BDA); the values were populated by the BIOS. The first KB was actually the Interrupt Vector Table (IVT), then came BDA values for items such as COM/LPT port addresses, memory size, keyboard buffer, soft reset behavior, etc. MS-DOS boot sector would load initial code to 0:7C0, and would use 70:0 as the DOD data area.

Bah humbug, I think no one needs more than 64k 😂

The music goes hard

no, el 8088 es una variante del 8086, mas economica, el 8086 es de 1976 y el 8088 es de 1979

Talk about a blast from the past! When I was a teenager (pre-internet), I remember fighting with DOS and reading deep into manuals to squeeze out every free byte of RAM for my games. It could be quite intricate, and it took a while. It was almost like a game itself to find the right combinations.