Project Logs

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• Small-C port

  Leon • 04/17/2021 at 16:54 • 0 comments

  I almost finished the porting of Small-C to the Lion computer with 32bit integers instead of the 16bit that the original made for x86. I also made a linker for combining the object files it produces to a single executable file.

  I had a hard time with the different cpu endianness and the different cpu word size but I believe now I have solved all these problems.
  

  I almost finished the c library routines. Tiny Basic in Lion plays the role of a command line interpreter and so I added file and memory handling routines to it.
  

  If I could add structures in Small-C compiler it would be perfect and floating point would be nice too.

• Lion's Color Palette

  Leon • 01/12/2021 at 21:50 • 0 comments

  Lion32's controller now has 64Κ of video ram and supports 256 colors in mode 1.
  

  In 16bit Lion mode 1  the resolution is 320x200 and every pixel's color is defined by 4bits so 16colors/pixel but  I just added the feature to choose the 4bit combination from a palette of colors.

  Every bit can be assigned to any of the 3bits per RGB color of the ladder DAC in the base board.

  This is an example of a palette choice with more shades of red and a bit of blue, a mandelbrot calculated using the 64bit fixed point arithmetic of Lion's Tiny Basic:

• Lion shield board

  Leon • 10/19/2020 at 17:04 • 0 comments

  I made a shield board for the QMTECH Cyclone V Core Board to make the Lion computer circuit less messy.

  The board hosts:
  

  - XYZ DACs with separate voltage regulator

  - audio mixer opamp

  - the VGA resistor dac and connector
  

  - 512K fast 16bit sram

  - headers for all other connectors

• 32-bit Lion

  Leon • 07/19/2020 at 15:30 • 0 comments

  The paged memory thing was troubling me a lot, so I made a new version 32 bit Lion CPU, I'll not surprisingly call it Lion32. Lion32 can have a 32bit address bus with tons of linear addressed memory.
  

  I made it as compatible as possible with the 16bit Lion and so the software had not to be rewritten although it needed much debugging but system software and Tiny Basic are working now with the 32bit Lion.

  I have to make the java grinder compiler 32bit version to be able to run the games and develop new 32bit software.

  Most new commands have the .D extension to indicate that they use a 32 bit length.
  

  MOV A1,10 is the 16bit operation while the MOV.D A1,10 is the 32bit

  the same with ADD.D SUB.D AND.D CMP.D etc

  All JUMPS and indirect addressing use 32 bits  
  

  Maybe I'll create a new project page for Lion32.
  

• Lion core for MiSTer

  Leon • 03/24/2020 at 20:30 • 1 comment

  A friend lend me his MiSTer board and as I had a lot of time because of  various restrictions due to corona virus (here in Greece) I ported Lion to the mister board.

  Most things work well but there are some differences in keyboard behaviour and so to play the games well you need a usb joystick, also there is no serial port and XY-Display support as in the original Lion.

  VGA output is a bit dark and redish I don't know why. (now fixed)
  

  HDMI is better but both outputs are darker than in the real Lion computer (now fixed).

  You can find the core in a zip file at the files section.

• Sound improvements

  Leon • 03/02/2020 at 11:40 • 0 comments

  In order to have better sound effects to add in the future to Galaxians clone or other games, I made some additions.
  

  In every channel I added the option to add a second frequency related to the playing one. This frequency can be up to an octave higher. It is controlled with a 4 bit parameter n.
  

  An other change is that the noise generator is clocked by the frequency of a channel when noise is enabled in that channel and its output is less harsh.

• Lion got vector graphics too!

  Leon • 10/19/2019 at 14:38 • 0 comments

  Added a vector graphics controller in the fpga with 4K dedicated ram for 1024 vector end points.
  

  Now it uses 3x MPC4822 12bit dacs for all channels.
  

  It produces the x,y,z output signals that I feed in my recently acquired HP-1330A X-Y Display Monitor.

  I implemented the Bresenham's line algorithm in the fpga to draw a line from the previous drawn point to the last one.
  

  I converted the Astro java demo game for vector graphics!

  Raster and Vector graphics are totally independent and can display concurrently.

  The following picture was taken before implementing the line draw algorithm:
  

  
  And the next photo is with the line algorithm, unfortunately with my phone camera lines look fat, in reality they look much better:
  

• Sound

  Leon • 09/08/2019 at 17:30 • 0 comments

  Sound capabilities are not advanced in Lion but...
  

  I increased the sound channels to 3 and added 255 step 8bit digital volume control for each one.

  A channel outputs a square wave signal with frequency  obtained by dividing 200khz by a 13bit number.
  

  A channel can be mixed with the white noise (lfsr) channel, noise comes with a frequency bandwidth limit.

  Every channel can be enabled with 8 different duration values 2sec, 1sec, 0.5 sec,  ....

  Status of any channel is available to determine if it has finished playing the previous note in order to send it a new note but a channel can be interrupted any time to start a new note.
  

• Cyclone V FPGA

  Leon • 09/07/2019 at 09:58 • 0 comments

  Moved the project to Cyclone V FPGA 5CEFA2F23I7, now I don't use an external static ram chip because this FPGA has enough internal ram for Lion's 128K ram + 32K Video ram + 12K sprite ram. It also has plenty IO pins for new features and it's logic elements are faster.
  

• PS/2 keyboard controller

  Leon • 07/14/2019 at 23:30 • 0 comments

  At last I wrote a controller for PS/2 keyboard in the fpga. It has a 16 key queue.

  I was postponing it and was using an external board instead, but once I started, it was easy and fun.

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