| Concept                       | SCSC             | AS65             | Merlin |
|-------------------------------+------------------+------------------+--------|
| origin                        | .OR              | org              |        |
|                               |                  |                  |        |
| target address                | .TA              |                  |        |
|                               |                  |                  |        |
| include                       | .IN              |                  |        |
|                               |                  |                  |        |
| comment                       | *                | ;                |        |
|                               | >1 space         |                  |        |
|                               |                  |                  |        |
| label                         | at left          |                  |        |
|                               |                  |                  |        |
| equ                           | .EQ              | =                |        |
|                               |                  | equ              |        |
|                               |                  |                  |        |
| binary                        |                  | %00000001        |        |
|                               |                  |                  |        |
| macro                         | .MA macro_name   | macro_name macro |        |
|                               | .EM              | endm             |        |
|                               |                  |                  |        |
| if                            | .DO              | if foo = 1       |        |
|                               | .ELSE            | endif            |        |
|                               | [.ELSE] (toggle) |                  |        |
|                               | .FIN             |                  |        |
| data                          |                  |                  |        |
| - word (LE)                   | .DA expr         |                  |        |
| - byte (LSB)                  | .DA #expr        |                  |        |
| - byte (MSB)                  | .DA /expr        |                  |        |
|                               |                  |                  |        |
| ascii string                  |                  |                  |        |
| - normal use                  | .AS "foo"        |                  |        |
| - arb. delimeter              | .AS dfood        |                  |        |
| - high bit set                | .AS -"foo"       |                  |        |
| - last high bit opposite      | .AT "foo"        |                  |        |
|                               |                  |                  |        |
| hex string                    | .HS              |                  |        |
|                               |                  |                  |        |
| reserve space (block storage) | .BS <bytes>      |                  |        |
|                               |                  |                  |        |

Things to ignore
| Concept | SCSC                   | AS65 |
|---------+------------------------+------|
| title   | .TI <lines/page>,title |      |
| file    | .TF filename           |      |
  


* AS65 notes
https://github.com/Klaus2m5/6502_65C02_functional_tests/blob/master/6502_functional_test.a65


* SCSC notes

    .DO -- Conditional Assembly                 5-9
    .ELSE -- Conditional Assembly               5-9
    .FIN -- Conditional Assembly                5-9
    .MA -- Macro Definition                     5-11
    .EM -- End of Macro                         5-11


* Edasm notes
http://mirrors.apple2.org.za/ftp.apple.asimov.net/images/programming/assembler/EDASM.DSK

** How to run
Boot from the disk
type "- edasm.system"

** Differences from manual
The manual claims that "MSB ON" is the default.

:ASM FOO.TXT
SOURCE   FILE #01 =>FOO.TXT
0000:41 42 43        1           ASC   "ABC"
0003:                2           MSB   OFF
0003:41 42 43        3           ASC   "ABC"
0006:                4           MSB   ON
0006:C1 C2 C3        5           ASC   "ABC"

* Sweet 16
http://amigan.1emu.net/kolsen/programming/sweet16.html
http://twimgs.com/informationweek/byte/archive/Apple-II-Description/The-Apple-II-by-Stephen-Wozniak.pdf

| R0  | Accumulator                                     |
| R12 | Subroutine stack pointer                        |
| R13 | Comparison results                              |
| R14 | Status (prior result register << 8 + carry bit) |
| R15 | PC                                              |

| 00 | Return to 6502 mode    | RTN      | 1 |                                         |
| 01 | Branch always          | BR       | 2 |                                         |
| 02 | Branch if no carry     | BNC      | 2 |                                         |
| 03 | Branch if carry        | BC       | 2 |                                         |
| 04 | Branch if plus         | BP       | 2 |                                         |
| 05 | Branch if minus        | BM       | 2 |                                         |
| 06 | Branch if zero         | BZ       | 2 |                                         |
| 07 | Branch if nonzero      | BNZ      | 2 |                                         |
| 08 | Branch if minus 1      | BM1      | 2 |                                         |
| 09 | Branch if not minus 1  | BNM1     | 2 |                                         |
| 0A | Break                  | BK       | 1 | BRK                                     |
| 0B | Return from subroutine | RS       | 1 | PC <- [----R12]                         |
| 0C | Branch to subroutine   | BS       | 2 | [R12++++] <- PC(R15); PC(R15) += offset |
| 0D | -                      |          |   |                                         |
| 0E | -                      |          |   |                                         |
| 0F | -                      |          |   |                                         |
| 1n | Set                    | SET R7   | 3 | Rn <- constant                          |
| 2n | Load                   | LD R7    | 1 | R0 <- Rn                                |
| 3n | Store                  | ST R7    | 1 | Rn <- R0                                |
| 4n | Load indirect          | LD @R7   | 1 | R0 <- byte[Rn++]                        |
| 5n | Store indirect         | ST @R7   | 1 | byte[Rn++] <- R0                        |
| 6n | Load double indirect   | LDD @R7  | 1 | R0 <- word[Rn++++]                      |
| 7n | Store double indirect  | STD @R3  | 1 | word[Rn++++] <- R0                      |
| 8n | Pop indirect           | POP @R3  | 1 | R0 <- byte[--Rn]                        |
| 9n | Store pop indirect     | STP @R3  | 1 | byte[--Rn] <- R0                        |
| An | Add                    | ADD R3   | 1 | R0 <- R0 + Rn                           |
| Bn | Sub                    | SUB R3   | 1 | R0 <- R0 - Rn                           |
| Cn | Pop double indirect    | POPD @R3 | 1 | R0 <- word[----Rn]                      |
| Dn | Compare                | CPR R3   | 1 | R13 <- A0 - Rn                          |
| En | Increment              | INR R3   | 1 | Rn++                                    |
| Fn | Decrement              | DCR R3   | 1 | Rn--                                    |

* Horrible error messages
** redbooka
       CPY   $#0 COMMENT TEXT

* The plan
- Make instructions simple data.
- Make the first pass do almost everything: pass two just sees data variants.

It's a bit tricky:

1. Parse instruction.
  1. Set the current label to the current address, unless it's an equate
  2. Set the org/target immediately, updating current address.
  3. Force equates to evaluate immediately.
  4. Evaluate instructions.



** How it works now
asm.Load
  for each line:
    Flavor.ParseInstr(...)
    passInst
      Set address if ORG
      in.Compute
      Update addr
asm.Pass2
  passInst