Long ago, before access to the Internet was cheap and plentiful, and way before search engines made finding this kind of information easy, this was a priceless find for an aspiring low-level programmer. All the (semi-)common PC hardware and software documented in one place.
Endless hours spent exploring VGA hardware registers and trying to apply them for cool visual effects. Learning how the then-new 32-bit Windows interacted with DOS extenders, and trying to make a homemade - very basic - operating system that could do it, too. The thrill of writing a Terminate and Stay Resident alarm clock, and having it finally not explode...
I have very fond memories of the Ralf Brown's Interrupt List.
I was using this before 2018. I used to write TSR applets for data collection. Knowing what interrupts were being was critical. It could mean the difference between your code working and it dying somewhere in expanded memory space.
Linux system calls WERE 80h. If your code is still using an interrupt to access kernel functions then you've got problems. Syscall exists for the simple reason that interrupts are expensive.
x86-64 introduced a `syscall` instruction to allow syscalls with a lower overhead than going through interrupts. I don't know any reason to prefer `int 80h` over `syscall` when the latter is available. For documentation, see for example https://www.felixcloutier.com/x86/syscall
Running disassembly on the system, VGA, and other add-in card BIOSes was often helpful. I recall figuring out how to cycle the palette faster than calling an interrupt, although it would still require vsync to prevent snow* and tearing.
* When updating the overscan region border color on some video cards DACs via direct port I/O, there would be random speckling of dots of previous and new colors like analog snow if synchronization to wait for the vertical blanking interval wasn't observed. This is the sort of shit emulation doesn't reproduce faithfully. It sometimes took having access to a lot of hardware to verify a program doing hardware-specific VGA tweaks worked correctly.
There was unloved informatics in school and loved informatics at home. Unloved informatics consisted of graph flow optimizations. Loved informatics consisted of EGA programming and IRQ interrupt handling for multiple keypress detection and other stuff. Both informatics were in Turbo Pascal, but in sport olympiads going to interrupts or assembler was prohibited. Not that it was going to help, but… when olympiads end, I was going those doors again, and others did not. For others my loved informatics was door remaining shut.
20 years later it is an excercize to find a device where loved EGA programming tricks work. Only unloved informatics remained
86Box is what you want for this kind of nostalgic programming, comrade.
Our teachers didn't know much about this stuff in school. The origin of my username here (and elsewhere) is from those classes at school; I once submitted an assignment that, under certain conditions, used inline asm in Turbo Pascal to do "INT 19h". Had to explain it later, but thankfully that particular teacher was more amused than offended.
This was, and for some purposes still is, one of the most useful documentation sets for the PC architecture. It's worth noting that Ralf himself isn't a specialist low-level programmer, as this came from an era when there was a far smaller divide between users, power users, and developers.
For those way to young to even know what this is, it's basically like MDN web documentation but for the DOS era. It was a community-maintained API reference for IBM PC hardware, DOS operating system, and other software.
I remember looking at a print out of some of it in the late 80's and learning about the "list of lists", the critical section flag, and the alternate stack.
I'm not quite old enough to have needed to use this while writing my own software. But I've come back to it repeatedly while learning enough about the operation of DOS PCs to try my hand at reverse-engineering some games. That was at least 10 years ago. (It became clear that I'd bitten off more than I could chew, so no full game RE, but I documented a couple more file formats, wrote some file viewers, and learned a lot).
I too have spent hours of assembly code on PC hardware. My freshly downloaded copy of the interrupt list has always been at my (virtual) side when designing tests or libraries.
I think that has been one of the very first and largest information collection shared for free on the internet.
Kudos to Ralf Brown and whoever participated in keeping the list compete, accurate and timely.
This was invaluable when I was tasked with writing a stay-resident boot loader just after the turn of the century. Even then, such information was considered arcane and Ralf Browns Interrupt List was much better than any official documentation I could find.
When I came upon this list, and I don't remember how, I went from the The 97 Pound Weakling to a perfectly developed hacker. Seriously, it was a game changer and launched me into a game of catchup on the PC (I was a Apple II and C64 guy). I had so much fun at work with hacks but also making cool utilities.
presumably nothing because its about old devices which dont have UEFI.
that being said, i suppose you mean BIOS interrupts are silly and you dont really want to know about them these days. that's true. (theres more than bios stuff in this list tho).
for ppl looking to discover BIOS interrupts and their meanings in this list, follow the breadcrumb given and go and checkout EDK2.
Before there was PC Interrupts, there was the The Prgrammer's PC Sourcebook and similar available at specialized bookstores like Computer Literacy Bookshops. Regular bookstores would generally contain a few computer and programming titles, but they weren't necessarily the best references.
Long ago, before access to the Internet was cheap and plentiful, and way before search engines made finding this kind of information easy, this was a priceless find for an aspiring low-level programmer. All the (semi-)common PC hardware and software documented in one place.
Endless hours spent exploring VGA hardware registers and trying to apply them for cool visual effects. Learning how the then-new 32-bit Windows interacted with DOS extenders, and trying to make a homemade - very basic - operating system that could do it, too. The thrill of writing a Terminate and Stay Resident alarm clock, and having it finally not explode...
I have very fond memories of the Ralf Brown's Interrupt List.
I was using this before 2018. I used to write TSR applets for data collection. Knowing what interrupts were being was critical. It could mean the difference between your code working and it dying somewhere in expanded memory space.
Absolutely. Title says 2018 but it really comes from the dawn of pc. DOS was at 21h, and now linux system calls in x86 are INT 80h.
Linux system calls WERE 80h. If your code is still using an interrupt to access kernel functions then you've got problems. Syscall exists for the simple reason that interrupts are expensive.
What do you mean by that? Most syscalls are still interrupt based.
x86-64 introduced a `syscall` instruction to allow syscalls with a lower overhead than going through interrupts. I don't know any reason to prefer `int 80h` over `syscall` when the latter is available. For documentation, see for example https://www.felixcloutier.com/x86/syscall
32 bit x86 also has sysenter/sysexit.
Int 80h still works as well as ever on i386.
I recently found out about swi 0x123456 on ARM...
many of the int 21h interrupts were virus install checks, telling for the future direction of microsoft?
Running disassembly on the system, VGA, and other add-in card BIOSes was often helpful. I recall figuring out how to cycle the palette faster than calling an interrupt, although it would still require vsync to prevent snow* and tearing.
* When updating the overscan region border color on some video cards DACs via direct port I/O, there would be random speckling of dots of previous and new colors like analog snow if synchronization to wait for the vertical blanking interval wasn't observed. This is the sort of shit emulation doesn't reproduce faithfully. It sometimes took having access to a lot of hardware to verify a program doing hardware-specific VGA tweaks worked correctly.
There was unloved informatics in school and loved informatics at home. Unloved informatics consisted of graph flow optimizations. Loved informatics consisted of EGA programming and IRQ interrupt handling for multiple keypress detection and other stuff. Both informatics were in Turbo Pascal, but in sport olympiads going to interrupts or assembler was prohibited. Not that it was going to help, but… when olympiads end, I was going those doors again, and others did not. For others my loved informatics was door remaining shut.
20 years later it is an excercize to find a device where loved EGA programming tricks work. Only unloved informatics remained
86Box is what you want for this kind of nostalgic programming, comrade.
Our teachers didn't know much about this stuff in school. The origin of my username here (and elsewhere) is from those classes at school; I once submitted an assignment that, under certain conditions, used inline asm in Turbo Pascal to do "INT 19h". Had to explain it later, but thankfully that particular teacher was more amused than offended.
This was, and for some purposes still is, one of the most useful documentation sets for the PC architecture. It's worth noting that Ralf himself isn't a specialist low-level programmer, as this came from an era when there was a far smaller divide between users, power users, and developers.
I wonder how things were done in this thing: https://en.wikipedia.org/wiki/Sun386i
Was that DOS emulation running some real DOS that though it was invoking BIOS calls?
According to a HN submission 3 years ago, evidently, Peter Norton once wrote a book on the 386i:
https://www.amazon.co.uk/exec/obidos/ASIN/0136616127/ref%3Dn...
For those way to young to even know what this is, it's basically like MDN web documentation but for the DOS era. It was a community-maintained API reference for IBM PC hardware, DOS operating system, and other software.
Oh the memories :) I still have somewhere a dot-matrix printed copy of the list I used religiously in the 90's
I remember looking at a print out of some of it in the late 80's and learning about the "list of lists", the critical section flag, and the alternate stack.
I'm not quite old enough to have needed to use this while writing my own software. But I've come back to it repeatedly while learning enough about the operation of DOS PCs to try my hand at reverse-engineering some games. That was at least 10 years ago. (It became clear that I'd bitten off more than I could chew, so no full game RE, but I documented a couple more file formats, wrote some file viewers, and learned a lot).
I too have spent hours of assembly code on PC hardware. My freshly downloaded copy of the interrupt list has always been at my (virtual) side when designing tests or libraries.
I think that has been one of the very first and largest information collection shared for free on the internet.
Kudos to Ralf Brown and whoever participated in keeping the list compete, accurate and timely.
HTML version if you're just curious about what it looks like (all the links on the linked site seem to be zip files).
https://www.ctyme.com/rbrown.htm
This was invaluable when I was tasked with writing a stay-resident boot loader just after the turn of the century. Even then, such information was considered arcane and Ralf Browns Interrupt List was much better than any official documentation I could find.
Many hours spent reading this even if I was quite late to the party.
When I came upon this list, and I don't remember how, I went from the The 97 Pound Weakling to a perfectly developed hacker. Seriously, it was a game changer and launched me into a game of catchup on the PC (I was a Apple II and C64 guy). I had so much fun at work with hacks but also making cool utilities.
Are there any interviews with Ralph Brown around?
It doesn't help that he's not the only RB.
how much of this info has been subsumed by standardized uefi?
presumably nothing because its about old devices which dont have UEFI. that being said, i suppose you mean BIOS interrupts are silly and you dont really want to know about them these days. that's true. (theres more than bios stuff in this list tho).
for ppl looking to discover BIOS interrupts and their meanings in this list, follow the breadcrumb given and go and checkout EDK2.
Before there was PC Interrupts, there was the The Prgrammer's PC Sourcebook and similar available at specialized bookstores like Computer Literacy Bookshops. Regular bookstores would generally contain a few computer and programming titles, but they weren't necessarily the best references.
Was my bible at some point. Thanks for memories