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Yes. There's an even more extraordinary story about them travelling to demonstrate their implementation of BASIC to the MITS team. They realise they have not

Yes. There's an even more extraordinary story about them travelling to demonstrate their implementation of BASIC to the MITS team. They realise they have not written a bootloader for the Altair, and Allen writes out a bootloader on the plane, which works when they get to MITS. https://en.wikipedia.org/wiki/Altair_BASIC#Origin_and_development https://en.wikipedia.org/wiki/Altair_BASIC#Origin_and_develo... My first encounter with a real Microsoft BASIC wasn't for another 15 years; the interpreter-only QBASIC that came with Halvorson & Rygmyr's Learn BASIC Now, which was a great book I gave away and now feel the urge to repurchase for nostalgia's sake. I used it for my GCSE Computer Science project.

WalterBright 5y ago
Writing an 8080 emulator on the -10 is not extraordinary, after all, it's a trivial instruction set. What was extraordinary is Allen realizing he could do this as a shortcut.
- WalterBright 5y ago
  An 8080 has what, 40 opcodes? All doing simple things like "add" and "mov". https://altairclone.com/downloads/manuals/8080%20Programmers%20Manual.pdf https://altairclone.com/downloads/manuals/8080%20Programmers...
  - phkahler 5y ago
    I learned on an 8080 system (Interact) that also had MS basic. Almost every one of 256 op-codes is used on the 8080. That's not to say there were that many instructions. For example register-to-register move might be considered one instruction but the source and destination register are encoded into that one byte so there are many reg-reg moves. Same with add sub, etc... My father wrote a disassembler in basic to read out the ROM and he made his own mnemonics which amounted to probably 20-40 actual instructions (I still have it and could look it up), but there were maybe 8 entries in the opcode table that did nothing.
    - WalterBright 5y ago
      https://pastraiser.com/cpu/i8080/i8080_opcodes.html https://pastraiser.com/cpu/i8080/i8080_opcodes.html As a pragmatic manner, I don't regard having the register and/or addressing mode encoded into the opcode as a separate opcode. Emulating a modern 64 bit processor would be a major chunk of work, but the old 8 bit ones are simple.
      - phkahler 5y ago
        If we exclude addressing mode then I think there are less than 26 instructions. Our mnemonic format was one letter (verb/op), one for source (a,b,c,d,e,h,l,w,x,y) and one for destination. I dont recall the letter for immediate, probably i but MIA for move immediate to a doesnt ring a bell for me. :-)
    - billforsternz 5y ago
      Yes, around 8 spare opcodes, and they were the ones Zilog used to escape into a large set of extensions for the (backwardly compatible to 8080) Z80.
      - phkahler 5y ago
        Can a Z80 be dropped into an 8080A socket? I'm thinking there were hardware differences.
        billforsternz 5y ago
        No absolutely not. 8080 was a 3 chip solution from memory. The 8085 was, like a Z80, a 40 pin DIP, but even here the compatibility was strictly software not hardware. And in fact the software compatibility was a little less than 100% because Zilog decided to add an overflow flag by changing the 8080/8085 parity flag to actually reflect overflow instead of parity on arithmetic instructions.
pieter_mj 5y ago
Interesting! Could you explain in a bit more detail how you used it for your CS project?
- unfocussed_mike 5y ago
  Oh I just mean, QBasic was the language I used for that project. I can't actually remember it in detail now, but this was when I was 15 or 16. It was a database application; I guess mine would have been music lending. I wonder if I still have the code. I definitely still wish I had the book. I really enjoyed QBASIC because of the gentle way you were exposed to better programming practices; I've always admired that. Five or six years later, my uni project was a BASIC-to-C transpiler for a simple dialect of BASIC as a teaching language with some specific language extensions for message-passing parallel programming. It had a simple IDE, too. In some ways it is a shame BASIC itself is really gone; modern implementations only have a whisper of its original simplicity.
  - pjmlp 5y ago
    Python seems to have taken its place, specially with all school calculators having some variant of MicroPython. It isn't the same thing though.
    - unfocussed_mike 5y ago
      Yes -- I think sort of the most basic BASIC programming is done with Scratch, and then they graduate to Python. In the UK I gather kids are taught Scratch and Python in an overlapping fashion, so they see the structure on the Scratch view and then have a better chance of understanding how the code works without being thrown off by the symbols. This is probably better in a pedagogical sense, and I am sure Scratch programmers have a better early understanding of flow control and things like loop termination conditions than BASIC programmers did; Scratch makes it more physical. But it does lose that absolute immediacy of being able to type simple words onto an empty screen and see it do things.
      - 5y ago

WalterBright 5y ago

Writing an 8080 emulator on the -10 is not extraordinary, after all, it's a trivial instruction set. What was extraordinary is Allen realizing he could do this as a shortcut.

WalterBright 5y ago
An 8080 has what, 40 opcodes? All doing simple things like "add" and "mov". https://altairclone.com/downloads/manuals/8080%20Programmers%20Manual.pdf https://altairclone.com/downloads/manuals/8080%20Programmers...
- phkahler 5y ago
  I learned on an 8080 system (Interact) that also had MS basic. Almost every one of 256 op-codes is used on the 8080. That's not to say there were that many instructions. For example register-to-register move might be considered one instruction but the source and destination register are encoded into that one byte so there are many reg-reg moves. Same with add sub, etc... My father wrote a disassembler in basic to read out the ROM and he made his own mnemonics which amounted to probably 20-40 actual instructions (I still have it and could look it up), but there were maybe 8 entries in the opcode table that did nothing.
  - WalterBright 5y ago
    https://pastraiser.com/cpu/i8080/i8080_opcodes.html https://pastraiser.com/cpu/i8080/i8080_opcodes.html As a pragmatic manner, I don't regard having the register and/or addressing mode encoded into the opcode as a separate opcode. Emulating a modern 64 bit processor would be a major chunk of work, but the old 8 bit ones are simple.
    - phkahler 5y ago
      If we exclude addressing mode then I think there are less than 26 instructions. Our mnemonic format was one letter (verb/op), one for source (a,b,c,d,e,h,l,w,x,y) and one for destination. I dont recall the letter for immediate, probably i but MIA for move immediate to a doesnt ring a bell for me. :-)
  - billforsternz 5y ago
    Yes, around 8 spare opcodes, and they were the ones Zilog used to escape into a large set of extensions for the (backwardly compatible to 8080) Z80.
    - phkahler 5y ago
      Can a Z80 be dropped into an 8080A socket? I'm thinking there were hardware differences.
      - billforsternz 5y ago
        No absolutely not. 8080 was a 3 chip solution from memory. The 8085 was, like a Z80, a 40 pin DIP, but even here the compatibility was strictly software not hardware. And in fact the software compatibility was a little less than 100% because Zilog decided to add an overflow flag by changing the 8080/8085 parity flag to actually reflect overflow instead of parity on arithmetic instructions.

pieter_mj 5y ago

Interesting! Could you explain in a bit more detail how you used it for your CS project?

unfocussed_mike 5y ago
Oh I just mean, QBasic was the language I used for that project. I can't actually remember it in detail now, but this was when I was 15 or 16. It was a database application; I guess mine would have been music lending. I wonder if I still have the code. I definitely still wish I had the book. I really enjoyed QBASIC because of the gentle way you were exposed to better programming practices; I've always admired that. Five or six years later, my uni project was a BASIC-to-C transpiler for a simple dialect of BASIC as a teaching language with some specific language extensions for message-passing parallel programming. It had a simple IDE, too. In some ways it is a shame BASIC itself is really gone; modern implementations only have a whisper of its original simplicity.
- pjmlp 5y ago
  Python seems to have taken its place, specially with all school calculators having some variant of MicroPython. It isn't the same thing though.
  - unfocussed_mike 5y ago
    Yes -- I think sort of the most basic BASIC programming is done with Scratch, and then they graduate to Python. In the UK I gather kids are taught Scratch and Python in an overlapping fashion, so they see the structure on the Scratch view and then have a better chance of understanding how the code works without being thrown off by the symbols. This is probably better in a pedagogical sense, and I am sure Scratch programmers have a better early understanding of flow control and things like loop termination conditions than BASIC programmers did; Scratch makes it more physical. But it does lose that absolute immediacy of being able to type simple words onto an empty screen and see it do things.
    - 5y ago