I’ve been very busy for the last few months, with many different things. This post will therefore be a bit of a mess, unfortunately. I’m at a place where I’ve been before a few times: not knowing the most interesting road to explore, since there are so many, and they are all fascinating and rewarding in their own way. First… Read more »
Since the last post I have added functionality necessary to make it possible to use the computer from a directly connected keyboard and screen. This required two things: Making the already written PS/2 controller VHDL implementation available to the Linux kernel by adding a PS/2 driver. Modifying the existing, and somewhat hacky, VGA controller for my video card and writing… Read more »
Whilst I did attach the graphics card to MAXI030 it was only to confirm that I could turn the card’s LED on and off. The VHDL for the Cyclone FPGA is in a sorry state and needs major work before I use it in any kind of meaningful way. Continuing on with MAXI030 my first port of call was to… Read more »
While working on the design for MAXI030 I completed another project: a new workbench microscope. After watching various videos on the topic, I came to the conclusion that a setup with just a camera and large TFT screen would be best for me, ie. one without eye pieces. I have various things wrong with my eyes, including poor stereoscopic vision,… Read more »
Though the 68020 based MIDI020 computer is a workable design, it suffers from a few problems: The main one is the board is not 100% reliable. Very occasionally it will fail to start. I’ve tried to diagnose this problem but without success I can only run the processor at half the rated speed, 12.5MHz if the SIMM slot is used… Read more »
Three PCBs arrived promptly from JLCPCB: The version 2 Test+SRAM board The version 2 Ethernet+Printer+Joystick board The version 1 Video+Sound board The version 1 of the top two boards are described at the bottom of the post about the MIDI020 68020 computer, if you haven’t read it. The first job was to build up the version 2 Test+SRAM board. Whereupon… Read more »
The build of MIDI020 is nearly finished. There’s been some hickups along the way, but I have managed to overcome them. My order to jlcpcb.com consisted of three boards: The MIDI020 main board The Test+SRAM expansion card The Ethernet+Printer+Joystick expansion card To make things interesting, and because I wanted to try them out, each came with a solder paste stencil…. Read more »
I2C, I²C or Inter Integrated Circuit is a synchronous serial protocol designed by Philips in the early 1980s for linking together ICs on PCBs so that they can exchange data. It operates in the same area as SPI, which I’ve talked about in this blog a few times. I’ve also talked about I2C before though not for a long time…. Read more »
My very first exploration of the 68000 family of processors involved designing a 68020 based computer consisting of 64KB of 16 bit wide EEPROM, 2MB of 32 bit wide SRAM and a quad UART. This board was called the MINI020, and in the end I did not get the PCB made up. I was not particularly happy with the PCB… Read more »
The physical construction of MAXI000 is complete: It looks good with the SIMM installed. I first attached the joystick parts. Testing the 9 pin Atari joystick went exactly as expected, as did testing the buttons on the Game port joystick I have. After writing a quick test routing for the SPI based MCP3002 (PDF) ADCs, I quickly encountered a problem… Read more »