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Showing posts from January, 2023

Pinouts

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 Eeprom programmer uses Mcp23008, 4040 with 28C64. Below is 28C64

eeprom programmer

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 Wanted to be able to program 28C64s and 28C256s because they looked easy and cheapish for up and coming boards, eg 1802, 6502. Was learning Vim at the time and was quite slow at getting code into Arduino IDE via Vim edit page. Also got preoccupied with tweaks and tips. Today, finally got Uno system to program clunky breadboards to read in 5 bytes and program them and verify via terminal. Here's the pic: (NB, numbers seem to be one off. Was expecting 65,66,67... but got 66,67,..Will sort it out. Here's the breadboard lashup: The schematic isn't all in one place, so that will be the next job. The main idea is to use the I2C bus of the Arduino to drive the two MCP23008s which have 8 I/O pins each. These, in turn, connect to the 28C64's I/O, and to the 4040 which generates 12 address lines and the control lines: CE*,OE* and WE*. The 28C64 was used because there were some already ordered from AliExpress and the MCP23008s were used because they were available at the local Ja...