How to use the Apple-1  (2020 firmware version only)

 

The 2020 firmware contains some major new features:

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• The KIM Uno is now compatible with both the KIM-1 and Apple-1. At the same time.
  FF00 <GO> to enter WozMon. FDDD <GO> (or FDDDR from Wozmon) to enter the Baum-Wozniak mini-assembler. It complements the KIM-1 programming style beautifully, now you don't need to memorise all the hex codes for instructions. A few keystrokes flip you between KIM-1 hex editing and the mini-assembler.

• The 1K EEPROM in the Arduino can now be used as a cassette tape. So you can save your programming work on the road.

An Apple-1 test drive

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Enter FF00 <go> (remember, <go> is Ctrl-G on the KIM Uno serial port!) to start the Apple-1's Wozmon.

Having the original Apple-1 manual at hand will be useful (link), see Page 3. There's quite a bit more to Wozmon (it is a user-friendly monitor after all), but the basics to get you going:

300: A9 00 AA 20 EF FF E8 8A 4C 02 03
            -- Enters series of values starting in address 0300
300.30A     <- Display contents of memory from 0300 to 030A
0300R       <- run the program starting at 0x300
               (character set will be printed, hit reset: <RS> or Ctrl-R)

You need some more Apple-1 knowledge, for instance you should not locate your program at 0x0200, as that is WozMon Workspace (it is where it stores its command line buffer). Anyway, entering a program from hand-assembled hex values is a step up from machines like the Altair (where you toggled in binary values using switches), but next-gen technology like an Apple-1 is quite powerful enough to assemble and disassemble for you.

For this, use the Baum/Wozniak mini-assembler. Originating from an amazing little disassembler that appeared in Dr. Dobb's in 1976, Mike Barry on the 6502 forum backported its later evolution, the mini-assembler, down from the Apple II. The program made its first appearance on the Gigatron (link for story). Wozniak needed just 850 bytes of 6502 code for all the functionality shown below:

FDDDR            -- fire up the mini-assembler (Run from FDDD).
                    Instructions are printed on-screen. Remember: Shift-R
300: LDA #$00    -- enter the same demo program at 0400
 TAX             -- note the leading space before add'l instructions
 JSR $FFEF
 INX
 TXA
 JMP $0302
300L             -- list the program just entered
<Return>         -- return to Wozmon
300R             -- run program
FDDDR            -- return to mini-assembler (to fix bugs & repeat)

<Ctrl-R>         -- reset back into the equally suave ROM of the KIM-1

FDDD <Ctrl-G>    -- aaaand back to the mini-assembler.

If you've ever used a real Apple-1 (emulator), you'll appreciate the luxury of this built-in additional software! It took a long time to load something like this from tape. A manual is here (link).

 

Loading and saving to your terminal/PC:

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You can load and save from the terminal emulator using Wozmon's hex dump and hex display functions, similar to what the KIM-1 ROMs offer as well. Make sure your terminal emulator can insert a delay between each character it sends so the 6502 can keep up. TeraTerm is a good choice.

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To save:

- type 300.30B if that is the range you want to save;

- start capture on your terminal emulator;

- hit return and once all the data has scrolled by, close and save the captured file.

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To load:

- just send the captured file, WozMon will 'type it in'.

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Loading and saving to cassette tape through the Apple-1

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The optional ACI (Apple Cassette Interface) is included in the KIM Uno. It uses the 1K EEPROM of the Arduino as a virtual cassette tape, and you can save up to 5 files on your 1K of tape space. In the old days, you would spool your cassette to an empty spot, note down the tape counter and start saving. It is now 2020, so this is what you do with today's 'solid state' tapes:

- store a tape counter number (a hex digit between $01 and $FE) in address $17F9

- the tape will instantly 'spool' to that place on the tape

- and you're ready to start saving using the ACI.

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The 256 byte ACI ROM is relocated from C100 to F100 to keep things nice and compact on the KIM Uno's memory map. Before you start saving or loading, spool the virtual tape to the right location. In WozMon:

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17F9: 03          - 03 is the location on the tape

                   (or actually, the filename, same thing)

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Then (you should read the ACI manual (link), or at least this nice summary (link)), but from WozMon:

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F100R            - run the ACI ROM from WozMon;

300.30BW         - W as in Write.

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Reading is done the exact same way, replacing the W with the R for Read.

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See the KIM-1 cassette tape functionality below for some other functions, like getting a directory of your tape; deleting files and initialising the tape. You do need to initialise the tape before you can do the above example of saving.

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Getting to know the Apple-1: Links

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I found the SB-Project website a great way to learn more about the Apple-1: link. It has an in-depth description of history, hardware and loads of PDF manuals.