MOnSter 6502

Complete working transistor-scale replica of the classic MOS 6502 microprocessor! The 6502 processor is renowned for its pivotal role in powering a multitude of iconic computer systems. It served as the heart of influential devices including the Apple ][, the Commodore PET, the Atari 400 and 800 gaming consoles, the BBC Micro, and even the beloved Tamagotchi digital pet.

Variants of the 6502 were also utilized in other popular machines like the Commodore 64, the Atari 2600, and the original Nintendo Entertainment System. The widespread adoption of the 6502 speaks to its lasting impact on the world of computing and gaming.
Due to the significantly increased capacitance of its design, the MOnSter 6502 operates at approximately 1/20th of the speed of the original processor. The maximum reliable clock rate achievable is approximately 50 kHz. The gate capacitance of the MOSFETs used in the

MOnSter 6502 serves as the primary factor limiting the clock speed. This gate capacitance surpasses that of the MOSFETs found on the original 6502 die, thus impacting the overall performance and speed of the MOnSter 6502.
As of the second revision of the board, the design statistics are as follows:

• Components that correspond 1:1 with transistors in the original 6502:
  • Total active transistors: 4237
  • 3218 enhancement mode n-channel MOSFETs
    • 2588 discrete
    • 630 located on 164 quad transistor array chips (26 of these 656 transistors are not used)
  • 1019 resistors (the original 6502 used depletion mode MOSFETs in place of resistors)
• 998 Additional parts present only in the MOnSter 6502:
  • 313 LEDs (The first revision board, shown in the video, has only 167 LEDs)
  • 270 extra MOSFETs for driving the LEDs
  • 20 filter capacitors
  • 32 bus capacitors
  • 2 zero-ohm jumpers for net tie reasons
  • 8 current limit resistors
  • 314 resistors for the LEDs
  • 36 diodes for ESD protection
  • 2 jacks for 5 V power: main and alternate location
  • 1 rectangular connector for the 40-pin "ICR" ribbon cable
• Total parts: 4769