Version 1.6 September 7, 2020

• ISA: QNICE Instruction Set Architecture updated to version 1.6. The changes
  are:

  • Interrupt system added.
  • HALT instruction changed. The semantics opened the way for CONTROL
    instructions such has HALT, RTI, INCRB and DECRB. The latter two mean that
    instead of adding/subtracting something to the upper byte of the SR, one
    can use these new commands.
  • SHL and SHR now modify Z and N condition flags.
    The new ISA is documented in doc/intro/qnice_intro.pdf.

• PERFORMANCE: The new ISA leads to a speed increase of about 7% as documented
  in q-tris_perf_test.asm compared to the old ISA. The main reason is that
  the new INCRB/DECRB only need two cycles compared to 4 cycles when switching
  banks the old way. This leads to faster sub-routine calls.

• MMIO: Cleaned up the MMIO address space and by doing so, changed all the
  locations of MMIO devices in sysdef.asm. This breaks binary compatibility
  with all software from version 1.5 and older, and therefore all this
  software needs to be reassembled and recompiled to run on version 1.6.

• CPU: Updates to reflect the new ISA. Added interrupt system. And a
  comprehensive CPU test was added (test_programs/cpu_test.asm) and multiple
  CPU bugs were fixed both in the emulator and in the hardware.

• MEGA65: Ported QNICE-FPGA to the MEGA65 (https://mega65.org/). This includes
  adding HDMI and HyperRAM support for the MEGA65.

• TIMER INTERRUPT GENERATOR: Added. Is internally running on 100 kHz and
  contains two independent counters (see sysdef.asm for details).

• INSTRUCTION COUNTER: Added. Counts all instructions executed by the CPU.
  Can be used for performance testing as shown in
  test_programs/q-tris_perf_test.asm and test_programs/mandel_perf_test.asm.

• UART: Added a 32 Byte FIFO to the UART. This was necessary because the
  MEGA65 serial over JTAG does not support RTS/CTS and therefore we needed
  more stability. Now RTS/CTS should be unnecessary in most cases.

• VHDL REFACTORINGS: The following system-wide refactorings have taken place
  with the goal to improve the code quality and the FPGA performance:

  • register_file optimized to use LUTRAM instead of registers.
  • replaced Tristate based inout DATA bus by separate DATA_IN and DATA_OUT.
  • got rid of the large if/elsif/then section in mmio_mux and replaced by
    more elegant direct logic assignments.
  • line endings in source files are now consistent with the unix scheme.

• MONITOR: Disassembler can now handle the new ISA.

• EMULATOR: Updated to reflect the new ISA.

• EMULATOR: Usability improved: At the "Q>" prompt the emulator now displays
  the address from which the last instruction was read from. When an emulator
  run is interrupted by CRTL/C (SIGINT) the statistics page now also lists
  the last 16 addresses from which instructions were executed.

• EMULATOR: Made the WebAssembly target compatible with Emscripten 1.39.14
  (and newer and it still works with 1.39.10 and some of the older versions,
  but not with the versions in between). The background of this phenomenon is
  explained here: emscripten-core/emscripten#10746

• EMULATOR: Adjusted the standard emulation speed to 13.0 MIPS because this
  is the average Q-TRIS performance. Peak performance observed so far is in
  test_programs/mandel_perf_test.asm: 13.62 MIPS

• Q-TRIS: Adjusted (slowed down) to match the CPU's speed increase by 7%.

• TOOLCHAIN: Native assembler updated to reflect the ISA changes.

• TOOLCHAIN: C code emitter and standard C library and Monitor library
  updated to reflect the MMIO changes. Standard C library recompiled to
  use register bank switching instead of the stack in all function calls.

• TOOLCHAIN: qtransfer: Convenient mechanism for transferring software
  (.out files) from the host computer to QNICE-FPGA. Details: doc/README.md

• TOOLCHAIN: Added support for Xilinx Vivado and made Vivado the main
  toolchain for our project. ISE is still supported though. Structured all
  hardware dependencies in the new folder 'hw' and added documentation
  in 'hw/README.md'.

• TOOLCHAIN: Added Ubuntu Linux support, which means it should also run on
  any other Debian based distribution. You might want to install xclip for
  more convenience (.out copied to clipboard after assembler ran).

• QBIN: All sample applications have been rebuilt due to changes in the ISA
  and the MMIO. A new download-link for the sample disk image is available:
  http://sy2002x.de/hwdp/qnice_disk_v16.img

• DOCUMENTATION: Added:

  • CONTRIBUTING.md
  • doc/README.md
  • doc/best-practices.md
  • doc/how-to-release.md
  • doc/int-device.md
  • doc/mips.md
  • hw/README.md
  • vhdl/hw/MEGA65/README.md

Version 1.5 March 22, 2020

This version greatly enhances the capabilities and the stability of the
emulator. Detailed description: emulator/README.md

• qnice-vga: VGA screen and PS/2 keyboard emulation
• qnice-wasm: WebAssembly/WebGL version that runs in the web browser

Version 1.41 December 30, 2016

• CPU: Fixed a bug which prevented things like ADD @--R4, R4 from working
  correctly, i.e. when a register was pre-decremented, then used for
  indirect reading and then the same register was the target register.
  See test_programs/predec.asm for a thorough description of this bug.
• EMULATOR: Can emulate the SD Cards introduced in Version 1.4 by being able
  to mount raw binary images of FAT32 devices. Have a look at doc/emumount.txt
  to see how it works.
• EMULATOR: 'dump' now shows ASCII values additionally to the hex values.
• Fixed a bunch of typos in various places and improved the documentation.

Version 1.4 December 26, 2016

1. Hardware read-only support for SD Cards. Make sure to read the hints and
   constraints in doc/contraints.txt. To directly test the hardware without
   using the new Monitor libraries, use test_programs/sdcard.asm

2. Software read-only support for FAT32 (new Monitor Libraries sd_library.asm
   and fat32_library.asm).

3. Monitor: It is now possible to browse directories and to load/run files
   directly from the monitor. Partition #1 of the SD Card is automatically
   mounted when using directory or file related functions.
   New top level folder "qbin" contains demo programs that can be executed.

4. C Compiler, Standard C Library: VBCC toolchain including VBCC compiler,
   VASM assembler and VLINK linker: Stable basic C environment including
   file system access (via fopen, fread, ...) and including convenient
   editing functions due to the fact, that the Monitor's new versatile
   gets_slf() function is used when reading from stdin. Everything is
   located in the "c" subfolder.

   Partition 1 of the SD Card is automatically mounted on-demand (upon first
   call of fopen). To test it, try c/test_programs/fread_basic.c

   Monitor library is available, that wraps monitor functions. To test it, try
   c/test_programs/shell.c

5. EAE: Extended Arithmetic Element added: This is a 16-bit signed/unsigned
   integer multiplication (with 32bit results), division and modulo
   co-processor. An example of the impressive speedup can be seen in the
   source code comments of mandel_perf_test.asm, which shows a speedup of
   factor 4.5 compared with release version 1.3.

   For testing it, use the following programs:
   test_programs/eae.asm
   test_programs/32bit-mul.asm

6. Further Library enhancements:

   • IO Library (Monitor): New gets function that supports CR or LF or CR/LF
     for ending the editing and that supports backspace (BS). New get_s that
     only function that reads until the buffer is full. get_slf that adds a LF
     in case the string input is ended by CR, LF or CR/LF.
   • Math Library (Monitor): mulu, muls, divu, divs, mulu32, divu32
   • String Library (Monitor): chr2lower, split, h2dstr

Version 1.3 May 6, 2016

• CPU: Significant speed improvement by removing old tristate driver:
  Evolution can be seen in mandel_perf_test.asm, which is now ~32% faster.
  Q-TRIS was even ~56% faster (now adjusted back to normal speed).
• CPU: Fixed a bug that prevented things like CMP 0x00AA, 0x00FF or things
  like OR @r0++, @r0, i.e. situations, where both operands perform an
  indirect access, where the source and destination operands are identical
  and where the source operand is post-incremented.
• ALU: Fixed CMP opcode behaviour: using the N flag it now treats the
  operands as unsigned and using the V flag it treats them as signed.
• ALU: Fixed V flag CPU bug (AND, OR, XOR)
• CYCLE COUNTER: Added. Counts clock cycles. Can be used for performance
  testing, as shown in test_programs/mandel_perf_test.asm.
• DEBUG MODE: If switch #2 is ON, then the LEDs are showing the current
  address bus value in real-time and on HALT the TIL shows the address
  of the executed HALT command.
• ASSEMBLER: Is able to handle labels on separate lines, improved error
  handling, CMP allows a constant as second operand.
• EMULATOR: Fixed CMP opcode behaviour (see above), fixed similar CPU bug
  as described above. Outputs address of HALT instruction. Also emulates
  the new cycle counter (register compatible), but instead of counting
  clock cycles, it is counting instructions.
• DOCUMENTATION: Added a programming card.

Version 1.21 February 13, 2016

• Fixed predecrement CPU bug
• Q-TRIS V1.0: Tetris clone and first game ever programmed for Q-NICE.
  Needs VGA and keyboard. Located in demos/q-tris.asm, starts at 0x8000 when
  being run via the monitor. Additionally, there is a special stand-alone
  autostart bitstream for the Digilent Nexys 4 DDR in dist_kit/q-tris.bit

Version 1.2 January 10, 2016

• UART: 115.200 baud, 8-N-1, CTS from now on
• VGA: now supports hardware scrolling and the lat9w-12 font, which supports
  besides the U.S. english charset also the German charset.
• MONITOR: system call table, supports scrolling on VGA using CTRL+F(orward)
  and CTRL+B(backward) and PgUp/PgDn as well as the cursor keys
• KEYBOARD: support for US and German keyboard locales and support
  for special keys like cursor keys, page-up/down, etc.
• HALT LED implemented as LED #15
• PORE system implemented. Most notably, this leads to not needing to
  press the reset-button after startup. Additionally, a reset message is
  displayed.
• ASSEMBLER: bugfixes and .DW now supports .EQUs and labels as arguments

Version 1.1 December 30, 2015

By default, version 1.1 behaves like version 1.0, i.e. input/output is done via UART, 8-N-1, 9.600 baud, RTS/CTS. But from version 1.1 on, you can now route the input via a PS/2 keyboard and the output via a 640x480 VGA monitor (80x40 characters):

• PS/2 keyboard support: enable via SW0
• VGA support: enable via SW1

Version 1.0 August 30, 2015

Classic "Environment 1" (aka env1), inspired by the classic QNICE/A evaluation board environment. Features:

• the original address layout: lower 32kB are ROM, upper 32kB are RAM
• 16bit words stored at each address word
• 256 registers
• memory mapped IO beginning at 0xFF00
• 4 TIL-311 displays at 0xFF10:
  0xFF10 is the value to be displayed
  0xFF11 lower 4 bit are a display bit mask
• Serial interface 8-N-1, 9600 baud, RTS/CTS beginning at FF20:
  0xFF21 status register
  0xFF22 read register
  0xFF23 write register

The package contains a working monitor application (version 0.2) including the mandelbrot demo application. Furtheron, the assembler and the emulator are included.

V0.9: ISA V1.2 on env1

Feature complete QNICE CPU, original instruction set architecture (ISA V1.2) as of December 2007, is running on a simulated version of the QNICE/A evaluation board. Slighly enhanced TIL display (4 digits instead of two plus a mask register). Lower 32kB are ROM, upper 32kB are RAM. No UART, yet. For convenient simulation in ISIM, the amount of register bank is restricted to 16 and RAM to 256 bytes; just change env1_globals.vhd to get the full amount of RAM of the real QNICE/A and the full register file size of the QNICE CPU.