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In this video I build a basic input circuit for the trainer board. This consists of up to 8 switches connected to the Z80 data bus via a 74xx244 buffer IC.
I show the schematic diagram of this circuit, then show how I'm using ASM80.com to write and download a test program. I then show the process of uploading that program to the EPROM using the TommyPROM.
Finally, I single step through the program and demonstrate how the input is isolated from the data bus until the point the Z80 program issues a "in" instruction.
Github repo
github.com/sra...
74HC244 video
• SN74HC244N Octal Buffer
TommyPROM
tomnisbet.gith...