MB03+ Ultimate will be a classic ZX Spectrum interface connected to edge connector. My goal is to create an interface based on modern FPGA and other chips compatible primary with it's predecessor MB02+ and others interfaces later. It's still in progress of development.


  • Z80 DMA, MBIDE, TurboSound, SAA1099, SounDrive/Stereo Covox/Specdrum, K-mouse implemented to FPGA.
  • CF and microSD cards socket.
  • MB02+ compatible memory addressing and expanded addressing to new BS-DOS (8KB pages)
  • 8MBytes SRAM, 2MBytes SPI FLASH
  • RTC DS3234 - extremely Accurate RealTimeClock with SRAM (possibility use as bios config) - full compatible with RTC72421 due to FPGA (ports, regs, etc.)
  • no FDD, no 8255 PIO on mother board
  • ULAplus compatible - no ports collision , FADI compliant, use with all ZX Spectrum (ZX 128+2 recommended)
  • WiFi ESP8266 - wifi module
  • powered by ZX Spectrum


  • GeneralSound all in FPGA
  • DivIDE and DivMMC all in FPGA,
  • Diskface, D40/D80, Beta disk memory support
  • WD2797A Floppy Controller on kid board


LMN128's Diary

2018/10/02: New World Record. ZX Spectrum with 8 Mega Bytes RAM! I got it to work on MB03+ Ultimate a made first test by run original MB02+ boot loader. This my loader is 23 years old. Unbelievable.

2018/10/02: After one week hard work i have implemented DMA to FPGA. I had to leart VHDL, because i got zxndma source code from Victor Trucco. I stopped coding my own DMA implementation and adjust and correct zxndma to works with real ZXS a MB03+. There was some timing differences, small bugs and other. There is still a lot of things to improve, but the main features are done.

2018/09/21: The v1.0 is finished finally. The soldering was rather demanding. I tested all from v0.0 and works very well.

2018/09/12: Routing is finished. The board 06- MB03+Ultimate v1 is going into production. Besides others i finally add support for Wifi module ESP8266. Internet is coming to MB03+ Ultimate.

2018/09/3: I have finished development of scheme of next test board. Next step is build board.

2018/08/31: I am hard working on next test board. It tooks me more time than i expect. I added 8MB SRAM, micro SD and USB sockets to it.

2018/08/24: I am chatting with Mario Prato, author of divMMC. It looks good. He promised send me source code of Xilinx.

2018/08/11 : I bought SD micro to CompactFlash adapter. It works very well. There is no speed problem. It will be good to find what is inside and use it in MB03+ Ultimate or implement it inside FPGA.

2018/08/10 : I have started the work on next board. Almost things are tested and current board v0.0 filled it's purpose.

2018/08/10 : I discussed with Andrew Owen about ZXI standard yesterday. I din't hear about it before. It's good idea. Finally he allocated 8 ports from ZXI range for MB03+ Ultimate purpose. Range is #203B to #273B. https://faqwiki.zxnet.co.uk/wiki/ZXI_standard.

2018/08/9 : I have soldered and tested RTC. I only implemented it as binary clock. It's enough for now. More on next test board.

2018/08/8 : Today is the day. 8/8/2018 , around at 8:00 I will say about MB03+ Ultimate to my friends.

2018/08/6 : I got the final logo. Many thanks to my friend Sharks (Zbynek Krajca).

2018/08/05 : I couldn't wait and added SounDrive, Stereo Covox and Czech Digital/Analog converters. I remembered my unfinished sound card MonsterBlaster. It was practicaly 8channels 8bits sound board. I have to find the scheme....

2018/08/04 : I am starting to work on RTC. I have chosen DS3234. It's rather big, but I think it's going to be very good.

2018/07/30 : I love General Sound and NeoGS. I re-soldered socket to Preci-Bus. I'm listening to some GS songs and I'm enjoying it. I'm also watching my older video.

2018/07/26 : I need a break but I am still working. I added Turbo sound! I must say the simulation model MikeJ's YM2149 from Jan 2005 is very good. I compared it with real AY-3-8912 in ZXS128+2 i don't hear a difference. Very good work MikeJ. I improved audio mixing to ACB stereo support. I can play SAA1099, TurboSound and ULA Beep. I like music.

2018/07/25 : I improved IDE implementation a bit and tested a lot of CF cards. All works on 3.3V. Both old and new.

2018/07/23 : CF - IDE works. It was harder than I expected, but it works very well.

2018/07/17 : I have started to work on implantation of IDE interface.

2018/07/17 : First test of MB03+ Ultimate v0.0 (04 board) together with it's older sister MB02+. No interfacing problem. This is my first board with 4 layers.

2018/07/13 : I decided to use new sockets for connecting ZXS peripherals including MB03+ Ultimate. Preci-Dip is high quality. I have improved my ZXS 128+2 and made ZX bus expander (05 board). Everything fits in perfectly . I call it Preci-Bus.

2018/07/12 : My ZX 128+2 needed ULA socket improvement for a long time. A lot of testing caused damage original socket. The worst was that ULAplus spreaded out pins and original ULA had a problem to fit it.

2018/07/09 : No more soldering wires. Finally the first test board connected directly to ZXS. Code name: MB03+ Ultimate v0.0

2018/06/26 : I made a MBIDE40 Compact Flash IDE interface (03 board) for practice with Eagle and for work and testing 3.3V CF cards.

2018/06/25 : First success. Interfacing of the 02 board looks good and due to it I implemented ULA Beep and SAA1099 (Sam chip) and it plays. WOW. Thanks a lot Miguel Angel Rodríguez Jódar for help and explanation about implementing the SAA1099.

2018/06/21 : Second interface 02 testing board done. But I still have to solder the connection wires. After that the board will be ready for testing audio output if interfacing will work.

2018/06/10 : Damn it. It seems every ZX Spectrum has different signal levels. It depends on the CPU brand/technology, PBC and others.

2018/06/06 : I am starting to test and measure of ZXS to FPGA interfacing. I have made the first 01 test board for this purpose. I have decided to use 3V3 Xilinx Spartan 6 FPGA. I have to solve the interfacing.

2018 May : I playing with FPGA. It's very cool. The possibilities are huge.

Spring 2018 : I am starting to learn Verilog, FPGA, Xilinx, Autocad Eagle, etc. So I am thinking about the best way to practice it and today I came up with an idea to make something for ZX Spectrum. So I told myself why not make a better, more modern version of MB02+. The development of MB03+ Ultimate begins!!!