4 ms·
> Assembly language is the lowest level of abstraction in computers - the point at which the code is still readable. For simple enough instruction sets it was
by dwc 10y ago
> Assembly language is the lowest level of abstraction in computers - the point at which the code is still readable.
For simple enough instruction sets it was not unheard of that people memorized the actual opcodes. In school, at the transition from terminals to micros, a friend of mine walked up to one of the new Commodore 6502 machines and entered a simple program in hex directly into the monitor program. For a while I had the common opcodes for the RCA 1802 memorized, due to working with a project board without an assembler (writing assembly on paper, then hand assembling into opcodes, then keying in the opcodes).
There's no returning to those days and I wouldn't if I could, but I can't help but think that I was lucky to have experienced that for the knowledge and perspective.
- Graham24 10y agoA9008502
- wolfgke 10y agoIf it is 6502 code, it is in assembly language: A9 00 LDA #$00 85 02 STA $02 But what is the intention of the code?
- mrkgnao 10y agoLooks more like an OEIS sequence identifier to me.
- wolfgke 10y agoThere is no OESIS sequence with this number, since by > http://oeis.org/eishelp2.html http://oeis.org/eishelp2.html "The A-number (for example A000108) is the absolute catalogue number of the sequence. It consists of A followed by 6 [not 7!] digits." Indeed: > https://oeis.org/A9008502 https://oeis.org/A9008502 "Sorry, the page you requested was not found"
- flohofwoe 10y agoWe used to test each other about Z80 opcodes staggering home drunk from the pub late at night as teenagers... LDIR? ED B0! LD HL,nnnn? 21! ... Ah... those were the times ;)
- sporkenfang 10y agoYou can still do that with MIPS and some of the other assemblers only used with embedded chips! A lot of people in my computer organization class five years ago ended up memorizing most of them, since it was sort of a side effect of having to go from opcodes to assembler and back again on quizzes.
- ajross 10y agoWoz famously hand-assembled the Apple ][ ROM, in fact.
- mrkgnao 10y agoWhy do people write ][ for the Apple II? I've seen it in a bunch of places now.
- rpeden 10y agoProbably because that's exactly how it was written on the machine's original logo[1]. I think it changed later on, though. [1] http://www.vintage-computer.com/images/apple2logo.jpg http://www.vintage-computer.com/images/apple2logo.jpg
- dwc 10y agoIt was also ][ on-screen.
- rpeden 10y agoNice, thanks for adding that. My first programming experience happened on an Apple ][ we had in my kindergarten classroom. It's been a long time since I've used one, though, so I didn't remember the on-screen logo.
- ajross 10y agoExactly that. It's how the machine announced itself at boot. You can see that right here: https://www.scullinsteel.com/apple2/ https://www.scullinsteel.com/apple2/
- vram22 10y ago> In school, at the transition from terminals to micros, a friend of mine walked up to one of the new Commodore 6502 machines and entered a simple program in hex directly into the monitor program. For a while I had the common opcodes for the RCA 1802 memorized, due to working with a project board without an assembler (writing assembly on paper, then hand assembling into opcodes, then keying in the opcodes). Ha ha, nice. Early on in my learning programming, I got a book about the Commodore 64. Written by a 16 year old (!) kid from the UK (IIRC), it had, in Commodore BASIC, the complete listing (using POKE statements :) of an assembler program for the C64. I typed the program into a C64 I had access to, over some days (making mistakes with the hex codes in the middle of the listing, a couple of times, and having to start the whole thing over), and finally ended up with a working assembler. Then wrote some 6502 assembly language C64 programs using the assembler, including for simple graphics. >There's no returning to those days and I wouldn't if I could, but I can't help but think that I was lucky to have experienced that for the knowledge and perspective. Agreed - and a lot more along the same lines, later on DOS and Unix too :)
- vram22 10y agoInteresting, just saw here: https://en.wikipedia.org/wiki/MOS_Technology_6502 https://en.wikipedia.org/wiki/MOS_Technology_6502 under section 1.5, "Computers and games", it says that: The 6510, a direct successor of the 6502 with a digital I/O port and a tri-state address bus, was the CPU utilized in the best-selling[48][49] Commodore 64 home computer. https://en.wikipedia.org/wiki/MOS_Technology_6510 https://en.wikipedia.org/wiki/MOS_Technology_6510