1.27 changes
* 10M08 flash read bug fix (which was broken from 1.24->1.26)
* Some cycle exact fixes. e.g.:
  - Timing on exiting init mode
  - audctl delay
* External clock fixes, there was a regression on the external clock in general. Also fixed it to create a pulse on both edges instead of just the rising edge! Fixes SIO2Midi for instance.
* Minimum paddle count corrected from 0 to 1 

1.26 changes:
*DO NOT USE ON 10M04 or 10M08*

* Cut 6581 bias (distortion on Basil!)
* Synchronous clock enable length fixed
* Disabled chips are no longer writable!


1.25 changes:
*DO NOT USE ON 10M04 or 10M08*

* Two tone timing fix recently discussed on atariage (suppress pulse on two reset cycle)
* Add per audio channel disable flag (user request)
* Updated pokeycfg to match (has a screen per section now too)


1.24 changes:
*DO NOT USE ON 10M04 or 10M08*

* Timing sdc constraint corrections
   - Fixes v3 flash issues on some builds
* Flash controller timing improvements
* Backported sid improvements from sidmax
   - Envelope timing matches 100%
   - Zero wave
* Mix some sio rxd noise into audio


1.23 changes:

 Pokey:
     Use schmit trigger input on SID and BCLK
     Additional synchronizers on sio clock in and sio input data
     Fix misalignment with enable signal issue on synchronous input
  v3:
     Add spdif output
     Add ps2 keyboard input (iso keyboard only for now)
     Use real clock oscillator
  config:
     Fix bug in init of pal/ntsc mode
     Default to pal mode
     Flash switched to wrapping mode (smaller)


1.22 changes:

  Environment:
    Upgraded to Quartus 20.1.1
  IP:
    Disabled wrapping burst mode on 10M08 flash access - it saves space but is non-functional! Issue raised with Intel.
  Config tool (1.0):
    Add some safety checks to the flashing tool
    - Allow halting and restarting the process (press break)
    - Check stdio error codes properly!
    Skip 0xff values (faster)
    'Secret key' (x!) to allow displaying some flash contents!


1.21 changes:
  SID/PSG:
    1MHz and 2MHz clock are generated using the C64 method.
    - PAL: 5/9 PHI2
    - NTSC: 4/7 PHI2
    (2MHz is 10/9 and 8/7)
    Previously the SID/PSG clock varied up to 0-10% by device since its using the internal oscillator (now the internal oscillator only leads to a jitter change, since it counts the phi2 length)
  Config tool (0.9):
    Add PAL/NTSC selection for these clock dividers


1.20 changes:
  SID:
    Wave and envelope timing verified/corrected vs 6581
    - 0 when all disabled, not 1
    - noise init fix
    - noise enable delay 2 cycles
    - pulse delay fix (asymmetric)
    - envelope stall bug fixed
    Fixed read of osc c register
    Sample support (dc offset in 6581 amplitude modulation, dc offset in 8580 ext in if digifix enabled)
    Filter
    - 6581 f distortion
    - Corrected 6581 and 8580 phase differences
    - Attenuate band pass (iirc) on 6581
 Common
   GTIA mixer fix
 Config tool
   Added sid digifix support (select 6581,8580 or 8580Digi)


1.19 changes:

  Platforms
    PokeyMax v1 backport
  Common
    Stereo auto version code corrected to SA
    Remove some whistling (different dac frequencies)
  Keyboard scan
    Works with TKII well enough, though will be further improved in future TKII firmware
  Sample
     Tested/fixes: Clipping, correct data nibble, irq
  SID
     Fixed corrupted Q values
  Config tool
     Much improved display refresh time
     No need to press control for arrow keys
     Fixed apply settings for 2nd flash location


1.18 changes:
SID
   filter q in flash (6581 or 8580)
   mixed waveforms in flash (6581 or 8580)
Pokey
    Force break anded in (turbo tape fix)
    Volume to flash (In large FPGAs)
Keyboard scan
   Inversion corrected
   Scan uses interrupts
   Scan run off pokey timer
   I2C clock run at 1.5MHz (over spec but stable until 3.5MHz)
   TKii/AKI should work
PSG
    volume to flash
Config
    Can disable devices by a register
Flash control fairness fix

1.17 changes:
Added sample player - Paula style with ADPCM (alpha test)
PSG volume linear or log
SID filter f in flash (6581 or 8580)
Pokey non-linear curve improved

1.16 changes:
i) 2nd order sigma delta dac excludes unstable top and bottom of range
ii) config tool update reads from the registers for the initial state
iii) right channel detection based on xor rather than 5 bits (covox 2 channel fix)

1.15 changes:
* Added flash support to M04 cores
* Added M04 support to flash program
* Flash program renamed to pokeycfg.xex

1.14 changes:
* Registers initialized from flash
* Flash access from the core
* Register to disable automatic mono detection
* Fix quad pokey mixer overflow bug
* Serial input 5 cycle clock delay (brings sio timing closer to pokey)

1.13 changes:
* Doubled clock rate of second order sigma delta
* Changed version type of some cores:
   xel stereo(pokey) => M02SX
   psg quad(pokey) covox => M08QP -> wire up like quad pokey with covox (A4,A5,A7)
   sid quad(pokey) => M08QS  -> wire up with A4,A5 and A6

1.12 changes:
* Second order sigma delta
* Improved pokey non-linear volume curve
* Channel playing detection (if R not playing, it plays L)
* xel stereo build (disables CS1)
* New SID core developer build
* New PSG core developer build

1.11 changes:
Implemented IRQ enable reg.

1.10 changes:
i) covox left channel: channel 1 + channel 4
ii) covox right channel: channel 2 + channel 3
iii) covox volume halved
iv) Added quad with covox memory map.
v) Added 4 channel covox.


... lots of early/pre-release changes...