a2audit/audit/notes.org

* Common bytes in FP and INT D0 ROMS
D17B 53
D1B3 54
D267 54
D273 54
D307 20
D32A 20
D337 20
D347 20
D51C 00
D57C F0
D665 20
D667 D6
D694 85
D69B FF
D6DC B1
D6F7 84
D729 4C
D72B D7
D747 F0
D74B D7
D768 85
D76E 65
* Links to things to test
** TODO [[https://groups.google.com/d/msg/comp.sys.apple2/RMnus8p6xp8/TDfD2HVtDwAJ][csa2: question on HGR behavior with enhanced 128K Apple //e]]
* Language card operation


| Bank 2 | Bank 1 |     | Action     | RAM          | Alt Bank 2 | Alt Bank 1 |
|--------+--------+-----+------------+--------------+------------+------------|
| C080   | C088   | R/W | WRTCOUNT=0 | READ ENABLE  | C084       | C08C       |
| C081   | C089   | R   | WRTCOUNT++ | READ DISABLE | C085       | C08D       |
|        |        | W   | WRTCOUNT=0 | READ DISABLE |            |            |
| C082   | C08A   | R/W | WRTCOUNT=0 | READ DISABLE | C086       | C08E       |
| C083   | C08B   | R   | WRTCOUNT++ | READ ENABLE  | C087       | C08F       |
|        |        | W   | WRTCOUNT=0 | READ ENABLE  |            |            |
Writing to high RAM is enabled when WRTCOUNT >= 2
Source: UtA2e, pg 5-24.
* Floating bus notes
17030 cycles for repeat: 2*5*13*131

UtAIIe: 5-40: Reading video data from a program
UtAII: 3-16: Switching screen modes in timed loops

My plan:

- A. Check that the floating bus works at all
- B. Save the address at each tick
  - Write the screen full of the lower byte of its address (0x00 -> 0xFF, so we can use 0 for timing)
  - Synch to a run of zeros, then delay to 000000000 counter.
  - Read 17030 values in a fixed-cycle, prime-relative-to-17030 cycles loop, and write to RAM
  - Write the screen full of the upper byte of its address (+ 0x80 if the lower byte is 0, so we can check 0x00->0xFF bytes)
  - Read the upper bytes
  - Check that they all match - should be able to add cycle count, then mod 17030 to find actual cycle number.

17030 * 2 = 34060 (0x850C)
If we end at 0xC000, we have to start at 0x3af4.
Perhaps we do lower bytes first, then upper? Then we can start at 0x7d7a
* Printing disassembly notes
$3A - PCL
$3B - PCH
Call PCADJ to update with length of currently-pointed-to instruction, then save A to PCL, Y to PCH.

Disassemble an instruction:
FE5E (LIST): Set counter to 20, call disassembler 20 times:

FE5E: 20 75 FE  920  LIST     JSR   A1PC       ;MOVE A1 (2 BYTES) TO
FE61: A9 14     921           LDA   #$14       ;  PC IF SPEC'D AND
FE63: 48        922  LIST2    PHA              ;  DISEMBLE 20 INSTRS
FE64: 20 D0 F8  923           JSR   INSTDSP
FE67: 20 53 F9  924           JSR   PCADJ      ;ADJUST PC EACH INSTR
FE6A: 85 3A     925           STA   PCL
FE6C: 84 3B     926           STY   PCH
FE6E: 68        927           PLA
FE6F: 38        928           SEC
FE70: E9 01     929           SBC   #$01       ;NEXT OF 20 INSTRS
FE72: D0 EF     930           BNE   LIST2
FE74: 60        931           RTS
FE75: 8A        932  A1PC     TXA              ;IF USER SPEC'D ADR
FE76: F0 07     933           BEQ   A1PCRTS    ;  COPY FROM A1 TO PC
FE78: B5 3C     934  A1PCLP   LDA   A1L,X
FE7A: 95 3A     935           STA   PCL,X
FE7C: CA        936           DEX
FE7D: 10 F9     937           BPL   A1PCLP
FE7F: 60        938  A1PCRTS  RTS

F8D0: 20 82 F8  225  INSTDSP  JSR   INSDS1     ;GEN FMT, LEN BYTES
F8D3: 48        226           PHA              ;SAVE MNEMONIC TABLE INDEX
F8D4: B1 3A     227  PRNTOP   LDA   (PCL),Y
F8D6: 20 DA FD  228           JSR   PRBYTE
F8D9: A2 01     229           LDX   #$01       ;PRINT 2 BLANKS {ACTUALLY JUST 1}
F8DB: 20 4A F9  230  PRNTBL   JSR   PRBL2
F8DE: C4 2F     231           CPY   LENGTH     ;PRINT INST (1-3 BYTES)
F8E0: C8        232           INY              ;IN A 12 CHR FIELD
F8E1: 90 F1     233           BCC   PRNTOP
F8E3: A2 03     234           LDX   #$03       ;CHAR COUNT FOR MNEMONIC PRINT
F8E5: C0 04     235           CPY   #$04
F8E7: 90 F2     236           BCC   PRNTBL
F8E9: 68        237           PLA              ;RECOVER MNEMONIC INDEX
F8EA: A8        238           TAY
F8EB: B9 C0 F9  239           LDA   MNEML,Y
F8EE: 85 2C     240           STA   LMNEM      ;FETCH 3-CHAR MNEMONIC
F8F0: B9 00 FA  241           LDA   MNEMR,Y    ;  (PACKED IN 2-BYTES)
F8F3: 85 2D     242           STA   RMNEM
...
...


F882: A6 3A     180  INSDS1   LDX   PCL        ;PRINT PCL,H  {PRECEDED BY CR, FOLLOWED BY '-'}
F884: A4 3B     181           LDY   PCH
F886: 20 96 FD  182           JSR   PRYX2
F889: 20 48 F9  183           JSR   PRBLNK     ;FOLLOWED BY A BLANK {3 SPACES, FINISH WITH X=0}
F88C: A1 3A     184           LDA   (PCL,X)    ;GET OP CODE
F88E: A8        185  INSDS2   TAY
...
...

300: LDA #0
 STA PCL
 LDA #3
 STA PCH
 LDX #0
 LDA (PCL,X)
 PHA
 JSR F88E
 LDX #3
 JSR F8EA
 JSR F953
 STA PCL
 STY PCH
 PLA
 RTS
* Auxmem tests

0000-01ff Zero
0200-03ff Main
0400-07ff Text
0800-1fff Main
2000-3fff Hires
4000-bfff Main
d000-ffff Zero