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• Nasty firmware bug fixed!

  Michael Wessel • 10/18/2025 at 14:14 • 0 comments

  I had a pretty nasty firmware bug encountered during my RetroChallenge 2025/10 contribution:

  https://hackaday.io/project/204153-3d-graphics-on-the-microprofessor-mpf-1b

  
  This is fixed now: 

  An uncaught "glitch" in the SRAM emulation due to noisy ADC button decoding. I have pushed a firmware update to PicoRAM Ultimate and PicoRAM 6116. The problem was that due to bad and noisy ADC thresholds button presses were detected that weren't real. Now, each time a button press is registered, the SRAM emulation is temporarily halted... but it requires the Z80 WAIT line to be connected, which I had not. This caused the issues. Obviously, you can't just halt SRAM emulation and not halt the CPU and expect it to run properly. The problem was fixed by adjusting the ADC threshold levels in the 6116.INI. But I added some UI Error Message now if such a "spurious" button press is detected caused by noisy ADC and inappropriate analog threshold levels in the init files. Hopefully, this will make the effect at least visible if it should happen again to someone. Because it really was a head scratcher, given that there was no visible indication for this error other than the CPU crashing or glitching. Now we at least see what's going on, and can the manually adjust the thresholds in the init files. Phew! So, it wasn't really a "firmware bug", as it worked as intended. But, I wasted a lot of time chasing red herrings because the spurious button presses were happening without me becoming aware of them. This specific ADC button level fell through the button decoding "switch / case" in the UI thread running on the second core, and a default case was missing - this is where the error message is being raised on the display now to make the user aware that his ADC threshold levels in the init files are inadequate. 

  Checkout the new firmware here: 

  https://github.com/lambdamikel/picoram6116

• New build and demo video by "Mein Elektronik Hobby" (in German)

  Michael Wessel • 10/17/2024 at 03:59 • 0 comments

  New build and demo video on the YouTube channel "Mein Elektronik Hobby" (in German). Glad it worked out of the box for you, Werner, and thanks for the positive review!
  

  
  

• Using EPROM Images without EPROMS

  Michael Wessel • 07/08/2024 at 14:21 • 0 comments

  The U7 socket on the Microprofessor MPF-1 is usually occupied by a 2716 EPROM containing user programs (or Tiny BASIC). However, by cutting a few PCB traces and setting the J1 jumper accordingly, it can also accommodate an additional 2 KBs of memory, using a 2nd 6116 SRAM. Hence, PicoRAM 6116 can be used instead of a standard 2716 user EPROM in U7. I got a couple of programs in a 2716 EPROM BIN image from the user DISCMIX on the German Classic Computing (Vintage Computer) Forum. In this video we are running his programs via PicoRAM 6116, and I also demonstrate how to convert EPROM BIN images such as the ones I got from DISCMIX into a PicoRAM digestible HEX format.

• John's MT-80Z Microprofessor variant with PicoRAM 6116

  Michael Wessel • 06/12/2024 at 16:12 • 0 comments

  John W. added PicoRAM 6116 to his E&L MT-80Z MPF-1B clone and, after initial troubles, got it to work flawlessly. Very nice machine and progress - thanks for sharing, John! Good to know that PicoRAM 6116 also works well with the less common Microprofessor family members.

• Using the MPF-1P Printer and PicoRAM 6116 simultaneously

  Michael Wessel • 04/13/2024 at 19:46 • 0 comments

  Let's print out a solution for the Towers of Hanoi with 5 disks:

• The Towers of Hanoi on the MPF-1P!

  Michael Wessel • 04/12/2024 at 17:53 • 0 comments

• Next-Level Software Development with PicoRAM 6116

  Michael Wessel • 02/26/2024 at 05:56 • 0 comments

  PicoRAM 6116 is taking Microprofessor MPF-1B software development to the next level - instead of keying in hex codes with the monitor, use a comfortable state-of-the.art Z80 assembler on the PC or Mac, assemble / compile the HEX file there, put it on SD card, and feed it to the Microprofessor! In this video I am developing a "Towers of Hanoi" program for the MPF-1B (recursive version) using asm80.com:

• Github repo available!

  Michael Wessel • 12/27/2023 at 17:08 • 0 comments

  https://github.com/lambdamikel/picoram6116

• Firmware v1.1 Release - "6116.INI File" Support

  Michael Wessel • 12/26/2023 at 22:42 • 0 comments

  Given the difference in ADC level configuration for the MPF-1P and MPF-1B, I decided to make these configurable. PicoRAM 6116 now reads the 6116.INI file on startup. The file specifies the machine type (MPF-1B or MPF-1P), ADC analog levels for the 5 buttons, 4 auto-load programs for the 4 banks which are loaded on startup, and one more flag (0 or 1) which can be used to debug / determine the voltage ADC levels for the analog buttons. If 1 is used, PicoRAM enters a "debugging loop" which constantly prints the ADC value on the display. The user can then press the buttons and note the values to be specified in the INI file for button configuration.
  

  I am attaching two 6116.INI files to the files section of the project (one for the MPF-1B, one for the MPF-1P). These need to be renamed as 6116.INI.
  

  This is the 6116.INI file for the MPF-1B - note that the file requires UNIX EOL (i.e., single LF EOL): 
  

  MPF-1B
  D00
  C00
  900
  700
  300
  100
  CLOCK.MPF
  DICE2.MPF
  COUNTER2.MPF
  EGGTIME.MPF
  0

  
  

• PicoRAM and the Microprofessor MPF-IP (One Plus)

  Michael Wessel • 12/25/2023 at 16:08 • 0 comments

  To my surprise, PicoRAM 6116 () worked almost out of the box on the faster (Z80A-driven) MPF-IP. The only thing I needed to adjust was the analog input for reading the UI buttons - VCC is much more noisy on the MPF-IP; I guess that's because of the VFD. Also, this is Rev. 4 now of the PCB - the little bodge wire pulls down the WAIT line of the Z80. I hence no longer have to hold the Microprofessor in RESET while operating the PicoRAM (or during boot / power cycle).

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