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28861Re: Altair 8800 Web Emulator

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  • corey986
    Jan 8, 2013
      I think Bill wasn't complete in his explanation of "backspace". Yes it's unsupported, but 4k basic supports "rub out". Which is what makes the vintage feeling when using the altair with basic cool. Rubout is simply an underscore to erase the last character. However it looks like this on a monitor. I'm not sure if a teletype backs up and strikes out the character, I can just tell you what happens on the altair when on terminal.

      For exc_ample....

      10 prr_int "hellll__o"

      Is actually read as

      10 print "hello"

      Since most "modern" people tend to hit the delete key not underscore, just map it to that.

      Btw, since the altair isn't the only vintage machine like this, the apple-1 is the same, so it must have been normal back then. On the Apple though the most common keyboard was a Datanetics which didn't have an underscore unless you hard wired one with jumpers, people I guess never used it much. Me my typing sucks, so how to "rub out" a character, is one of the first things I try to figure out on a platform.

      Fyi, Also I can't seem to get you simulator to work on my iPad...


      --- In midatlanticretro@yahoogroups.com, "who88777" wrote:
      > I would still like for backspace to not leave the page even if it won't be read properly by the software.
      > Paste is obviously not a feature of the original altair, but when pasting it should simulate typing of characters. The only way you will be able to load new software onto the emulated altair is through my program to read hex files from the terminal. It would be very tedious to do so without copy and paste working. Ditto for large BASIC programs.
      > The memory map is as follows after boot:
      > 0x0000 - JMP 0x8000 program
      > 0x4000 - End of RAM and top of stack for menu/loader (it automatically seeks the end of memory to set SP)
      > 0x8000 - Start of loader program ROM
      > 0x????? - End of ROM varies based on code size. It is over 20K because of the ASCII art
      > When loading altair BASIC or other programs the image is copied into memory and a JMP is executed to the base address. To save time for pre-loaded software the emulator itself memcpy's it into RAM via a command through port 250. If you use my hex-loader then the emulated CPU is doing all the work.
      > The base address for the Altair BASIC is 0x0000. You could reach the loader again if you can execute a JMP 0x8000 but its not expected you will ever get back.
      > The BASIC image I have is the one from SIMH. I also saw the 8K version but have been unable to get it to work. If I ever get around to emulating a disk drive I would like to see CP/M running.
      > --- In midatlanticretro@yahoogroups.com, "B. Degnan" wrote:
      > >
      > >
      > > > A few known issues:- Backspace doesn't work in the terminal- Paste
      > > > doesn't work in the terminal- Some layout issues on Safari- LEDs operate
      > > > more like hollywood computer lights rather than the PWM you'd see on the
      > > > real thing- Switches on the control panel don't look like the originals
      > > > (If somebody can get me a straight on photo of the Altair with switches
      > > > in various positions I could fix this)
      > >
      > > The backspace key does not work on the real terminal when using 4K BASIC.
      > > You may be able to backspace but then you'll get an error. So you're ok.
      > > why *would* paste work?
      > >
      > > what is the memory map of BASIC after successful load?
      > >
      > > Bill
      > >
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