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TGL-6502 Hardware Design

In this post I describe the hardware design of the TGL-6502 emulator board. The full schematic is available in the GitHub repository (PDF), it might be worth opening it in another window for reference while reading this post. I started this project as a challenge to see how much I could get out of the 8 pin DIP version of LPC810 microcontroller from NXP. This is one of the few ARM based controllers available in DIP format (the only other one I know of is also from NXP - the LPC1114. Some time ago I bought a Adafruit LPC810 Starter Kit and then later a handful of discrete LPC810 chips to fill u…

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Programming the TGL-6502

This post describes how to develop software for my TGL-6502 emulator board. The most recent update to the GitHub repository includes a desktop implementation of the emulator software so you don't need to build the hardware to write and test programs. Overview This is going to be a very long post unfortunately so I thought a brief executive summary would be useful. My goal in this post is to describe how you can develop and test software targeted at my 6502 emulator - to achieve that I will describe how to; Compile a version of the TGL-6502 firmware that runs on a desktop computer (Linux or Win…

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A Simple Serial (I2C/SPI) EEPROM Programmer

This is a small ATtiny84 based device to program I2C and SPI EEPROM chips over a serial port. As usual all code and schematics are available in GitHub. Background The TGL-6502 project uses an SPI EEPROM (the Microchip 25AA1024) to simulate the ROM exposed to the 6502 processor. To get the content into the ROM I added a simple serial protocol to the TGL-6502 firmware but as the firmware grew this functionality had to be dropped to free up some of the limited flash memory so I had to find an alternative method. I considered using a generic tool such as the Bus Pirate to program the EEPROMS or ev…

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