hw_build.txt

KickSmash Hardware Build
------------------------

Use the files in the desired `rev*` directory to have a fabrication
house build a PCB. I use JLCPCB with HASL for most of my builds.

** SOURCING

74FCT162244 is becoming difficult to find, but are still readily available
if you know what to locate. The part must be TSSOP-48 and 5V supply and
I/O with TTL signal compatibility. You can also use 74FCT16245 or 74FCT162245.
The main difference is drive strength, and either is more than a suitable
replacement for the drive strength of an EPROM. Known options:
+ IDT74FCT162244ATPAG8 -- I personally use for hand-soldering, sourced
                          from ebay.
+ 74FCT162244CTPAG - the part which is called out in the BOM, which is
                     unfortunately no longer available from LCSC.
+ 74FCT162244ATPACT - available from Rochester Electronics (qty 25+).
+ CY74FCT16244TPAC - Chucky uses these and knows that they work.
+ SN74ABT162244DGGR - these parts are still available from Mouser and
                      have been tested as compatible.
+ 74FCT162244CTPACT - this part appears to be compatible (untested)
+ QS74FCT162244ATPA - quantity from Rochester Electronics (untested)
+ CD74FCT162244ATMT - available from Rochester Electronics (untested)
+ 74FCT16244CTPAG8 - this part appears to be compatible (untested)
+ 74FCT16245ATPAG8 - ROTATE 180 degrees. Tested and confirmed working.
                     The 74FCT16245 and 74FCT162245 parts should work as
                     suitable replacements for 74FCT162244, but they MUST
                     be rotated 180 degrees from the footprint marking.
+ 74FCT162245CTPAG - ROTATE 180 degrees. See the comment above.


** IMPORTANT NOTE **
   Although it's listed in the BOM of some boards, do not use AO3400A
   for Q2 / Q3. Use 2N7002 MOSFETs instead. The AO3400A are too slow
   for reliable flashing from AmigaOS.

My recommended assembly order is:
    1. Top side STM32
    2. Top side Flash chips
    3. Bottom side 8 MHz oscillator and AM1117-3.3 voltage regulator
    4. Bottom side 74FCT162244 parts
    5. USB-C connector
    6. All passives
    7. LEDs are last
    8. Right angle header for STM32 SWD (if desired)
    9. Right angle header for KBRST pin (required)
   10. Right angle header for console (I usually don't install this)
   11. Bottom pin headers

For better in-system fit, you might choose to install the right angle
headers from the bottom side of the board.

The bottom pin headers are two 20-pin and two 9-pin. Note that they are
20-pin, not 21-pin, unless your Amiga has been modified to add more
address lines from a device such as Romy. Before installing any headers,
I recommend that you jump to programming with the ST-Link or by USB DFU.
If you need to remove shorts, improve soldering, or correct part
orientation, it's much easier to do without the pin headers in place.

You can choose to use machined pin (round) or lead frame (aka Flip-Pins).
Don't use standard Dupont-style male headers. These are too thick (0.5mm+)
and will damage your ROM sockets. Machined pins are around 0.35mm, and
lead frame pins are around 0.25mm. I like the lead frame pins, but have
discovered they are much more difficult to install in the Amiga ROM sockets
than machined pins. They also bend very easily.

For the LEDs, I use Purple (ultraviolet) for POWER, Orange for READ, and
Green for WRITE. You may choose to use a different color scheme. The reason
I like Purple for POWER is that it's the only LED which is on all the time,
and I found that Green is too bright for that.

After completing the build, follow the hw_programming.txt guide.