Base64 fx68k gateware — v1.2.0

Base64 fx68k gateware — v1.2.0

Updates the embedded SD card driver to sfsd.device v2.4, which is
noticeably faster.

Drive speed measured with SysInfo goes from 1,310,720 to 1,759,355
bytes/sec — about 34% — on otherwise identical hardware and gateware.

No gateware changes. Everything in
v1.1.1 is unchanged: 42.5 MHz fx68k, 24 MB
of fast RAM, mapROM from boot, SD card boot, cold boot from power-on.
Requires Base64 carrier board Rev C and an iCESugar-Pro module.

Driver by Matt Harlum (LIV2), maintained at
LIV2/amiga-par-to-spi-adapter.

Only the driver ROM baked into the bitstream changed. The RTL, the autoconfig
layout and the product IDs are the same, and sfsd.device still binds
unmodified. The SPI clock is unchanged, so the gain is entirely
in the driver.

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Installing

Plug a USB-C cable into the FPGA module. The on-board iCELink appears as a
virtual disk — drop the .bit file onto it and wait a few seconds while it
writes the SPI flash.

⚠ Do this with the module OUT of the Amiga

There is no protection on the module between its 5V rail and USB 5V.
Plugging in USB while it is seated ties the Amiga's 5V to your PC's with
nothing in between, and whichever is higher back-drives the other. If USB
has to stay attached while the module is installed, use a data-only
cable with the 5V conductor cut, leaving D+, D- and GND.

MapROM from v1.1.0 is unchanged and works with this bitstream, so there is
no need to replace it.

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Known limitations

Unchanged from v1.1.1: no DMA into the Zorro II fast RAM (set the mountlist
Mask to 0x001FFFFE), passive mode untested, and place-and-route variance
comparable to the timing margin.

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Checksums

SHA256  a34202d763e2d80f6bb2a34652dc794711e43a33fc85b360970abfa5074e4bac  base64_fx68k_v1.2.0.bit