Note: 0056 is considered the most recently opened address. You can also examine several locations at once, with all addresses on one command line. Note: Only the first location of the block 4F is considered opened. We can also combine the previous two examples into one command: Note: 004F is still considered the most recently opened location. Now let us examine a block of memory from the last opened location to the next specified location. Note: The bold typed characters are what the user types.Īll other characters are responses from the Apple 1. You can examine the contents of a single memory location by typing a single address followed by a Return. ![]() If an error is encountered during the parsing of the input line then the rest of the line is simply ignored, without warning!Ĭommands executed before the error are executed normally though. Tip: This can also be used to your advantage to correct typing errors, instead of using the back arrow key. Thus entering 12345678 as address will result in the address 5678 to be used. In that case it would be easiest to cancel the input and start all over again.Ĭanceling the input is done by pressing the ESC key.Īddress inputs are truncated to the least significant 4 hexadecimal digits.ĭata inputs are truncated to the least significant 2 hexadecimal digits. It's obvious that you can easily get confused when a line contains too many corrections or when an error is detected all the way at the other end of the input line. You'll have to keep track of the changes yourself. You can press the back arrow key to erase characters from the input buffer, but the erased characters will not be erased from the screen nor will the cursor position back-up. This overflow situation is indicated by a new back slash after which the cursor drops one line again.īecause of the primitive nature of the terminal there are not many line-editing features available. The input buffer can hold up to 127 character, if you type more characters before hitting the Return key the input line will be erased and will start again from scratch. You can now type address, data and commands which will be executed as soon as you press the Return key. The cursor position is represented by a flashing symbol. Once you do that a back slash '\' is printed on the screen and the cursor will drop down one line. The original Apple 1 did not come with a Reset circuit, which means that the user has to press the RESET button in order to get the machine started. It allowed the user to examine and change memory contents and it allowed machine language programs to be started. This ROM was filled with the legendary Woz Monitor. ![]() Remember that memory used to be very expensive at the time the Apple 1 was developed. ![]() The basic version of the Apple 1 had a total of 256 bytes of ROM! The Apple 1 was far more advanced, it did contain some ROM memory. You had to flip a few hundred switches in order to enter the first program, which was then able to load the real stuff in. When you powered that machine up it did absolutely nothing. The most popular "personal computer" back then, the Altair 8800, had no ROM at all. This software is programmed in ROM memory because ROM chips are non volatile and will not forget the contents when power is removed. Since the computer has just been powered up there must be some software in memory somewhere. It goes without saying that a piece of software must be executed. When a computer is powered up it must know what it must do.
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