28C256 EEPROM Writer

email: info@homebrew8088.com

This is a simple homemade EEPROM writer that any one can make.

To make a writer It requires the following

Breadboard w/jumpers
2 - MCP23S17 16-bit SPI I/O Expander
Raspberry PI

*note the project is 100% directed towards the 28c256 EEPROM's. but you should be able to adapt the concept to other sizes of EEPROM's

Schematics

Python code

32k.zip To run go to the command terminal in the folder with the files and type python3 32k.py

Includes

32k.py
SPI32k.py
unlock_code.asm (this is for unlocking 28c256 on my 8088 motherboard see attached video)

32k.py

#pyinstaller --onefile --hidden-import tkinter new.py

from tkinter import *

from tkinter import filedialog

from tkinter import messagebox

import os

from os import system

import SPI32k

def donothing():

print("Hello World")

def new_file():

text_field.delete(1.0,END)

main_window.title("32K 28C256 Writer")

main_window.file_and_path = ''

def open_file():

file_name = filedialog.askopenfilename(initialdir = "/home/pi",title = "Open",filetypes = (("Assembly","*.asm"),("all files","*.*")))

if file_name:

file_open = open(file_name)

file_data = file_open.read()

file_open.close()

text_field.delete(1.0,END)

text_field.insert(END, file_data)

main_window.file_and_path = file_name

main_window.title("32K 28C256 Writer " + main_window.file_and_path)

def save_file():

if(main_window.file_and_path == ''):

file_save = filedialog.asksaveasfile(mode='w', initialdir = "/home/pi",title = "Save",filetypes = (("Assembly","*.asm"),("all files","*.*")))

if file_save:

file_save.write(text_field.get(1.0,END))

main_window.file_and_path = file_save.name

main_window.title("32K 28C256 Writer " + main_window.file_and_path)

file_save.close()

else:

file_save = open(main_window.file_and_path, 'w')

file_save.write(text_field.get(1.0,END))

file_save.close()

def save_as_file():

file_save = filedialog.asksaveasfile(mode='w', initialdir = "/home/pi",title = "Save As",filetypes = (("Assembly","*.asm"),("all files","*.*")))

if file_save:

file_save.write(text_field.get(1.0,END))

main_window.file_and_path = file_save.name

main_window.title("32K 28C256 Writer " + main_window.file_and_path)

file_save.close()

def Compile_and_Upload():

if(main_window.file_and_path == ''):

messagebox.showinfo("Compiler Error", "File not open or saved!")

else:

file_save = open(main_window.file_and_path, 'w')

file_save.write(text_field.get(1.0,END))

file_save.close()

main_window.file_and_path_bin = main_window.file_and_path[:-4] + '.bin'

os.system("nasm " + main_window.file_and_path + ' -o ' + main_window.file_and_path_bin)

if os.path.exists(main_window.file_and_path[:-4] + '.bin'):

file_open = open(main_window.file_and_path[:-4] + '.bin', mode='rb')

file_data = file_open.read()

file_open.close()

Jump_code = [0XEA, 0X00, 0X00, 0X00, 0XF8]

SPI32k.Write_Memory_Array(0xFFF0, Jump_code)

print("JUMP CODE DONE JMP 0XF800:0X0000")

SPI32k.Write_Memory_Array(0x0000, file_data)

print("CODE DONE AT ADDRESS 0X0000")

else:

messagebox.showinfo("Compiler Error", "bin file was not compiled check NASM output for errors")

def Compile_code():

if(main_window.file_and_path == ''):

messagebox.showinfo("Compiler Error", "File not open or saved!")

else:

file_save = open(main_window.file_and_path, 'w')

file_save.write(text_field.get(1.0,END))

file_save.close()

main_window.file_and_path_bin = main_window.file_and_path[:-4] + '.bin'

os.system("nasm " + main_window.file_and_path + ' -o ' + main_window.file_and_path_bin)

if os.path.exists(main_window.file_and_path[:-4] + '.bin'):

print("COMPILE COMPLETE")

else:

messagebox.showinfo("Compiler Error", "bin file was not compiled check NASM output for errors")

def Read_Back():

print("JUMP CODE")

SPI32k.Read_Memory_Array(0xFFFF0, 16)

# Create the main window

main_window = Tk()

main_window.title("32K 28C256 Writer")

main_window.minsize(800, 600)

menubar = Menu(main_window)

filemenu = Menu(menubar, tearoff=0)

filemenu.add_command(label="New", command=new_file)

filemenu.add_command(label="Open", command=open_file)

filemenu.add_command(label="Save", command=save_file)

filemenu.add_command(label="Save As", command=save_as_file)

filemenu.add_separator()

filemenu.add_command(label="Exit", command=main_window.destroy)

menubar.add_cascade(label="File", menu=filemenu)

buildmenu = Menu(menubar, tearoff=0)

buildmenu.add_command(label="Compile -> Upload", command=Compile_and_Upload)

buildmenu.add_command(label="Compile", command=Compile_code)

buildmenu.add_command(label="Read Back 0xFFFF0", command=Read_Back)

menubar.add_cascade(label="Build", menu=buildmenu)

main_window.config(menu=menubar)

main_window.file_and_path = ''

main_window.file_and_path_bin = ''

text_field = Text(main_window)

#text_field.wrap (WORD)

text_field.pack(expand=True, fill='both')

# Run forever!

scrollbar = Scrollbar(text_field)

scrollbar.pack( side = RIGHT, fill = Y )

SPI32k.Start_SPI()

main_window.mainloop()

SPI32k.spi.close()

SPI32k.py

import spidev

import time

MCP23S17_WRITE_00 = 0b01000000

MCP23S17_READ_00 = 0b01000001

MCP23S17_WRITE_01 = 0b01000010

MCP23S17_READ_01 = 0b01000011

IOCON_0A = 0x0A

IODIRA = 0x00

IODIRB = 0x01

GPIOA = 0x12;

GPIOB = 0X13;

ALL_OUT = 0x00;

ALL_IN = 0xFF;

spi = spidev.SpiDev()

def Start_SPI():

spi.open(0, 0)

spi.max_speed_hz = 10000000

#Enable address pins

spi.xfer([MCP23S17_WRITE_01, IOCON_0A, 0b00001000])

#Setup ports

#8 bit Data

spi.xfer([MCP23S17_WRITE_00, IODIRA, ALL_OUT])

#Address 0-7

spi.xfer([MCP23S17_WRITE_00, IODIRB, ALL_OUT])

#Address 8-15

spi.xfer([MCP23S17_WRITE_01, IODIRA, ALL_OUT])

#Control Port

spi.xfer([MCP23S17_WRITE_01, IODIRB, ALL_OUT])

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00000111])

def Read_Memory_Array(Address, Count):

#8 bit Data out put

spi.xfer([MCP23S17_WRITE_00, IODIRA, ALL_IN])

#Turn on power

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00001111])

time.sleep(10000/1000000)

oAddress = Address

while Address < (oAddress + Count):

spi.xfer([MCP23S17_WRITE_00, GPIOB, Address])

spi.xfer([MCP23S17_WRITE_01, GPIOA, Address >> 8])

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00001010])

val = spi.xfer([MCP23S17_READ_00, GPIOA, 0x00])

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00001111])

print(hex(val[2]))

Address += 1

time.sleep(10000/1000000)

#Turn off power

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00000111])

def Write_Memory_Array(Address, code_for_8088):

#8 bit Data out put

spi.xfer([MCP23S17_WRITE_00, IODIRA, ALL_OUT])

#Turn on power

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00001111])

time.sleep(10000/1000000)

for i in code_for_8088:

spi.xfer([MCP23S17_WRITE_00, GPIOB, Address])

spi.xfer([MCP23S17_WRITE_01, GPIOA, Address >> 8])

spi.xfer([MCP23S17_WRITE_00, GPIOA, i])

time.sleep(10000/1000000)

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00001001])

time.sleep(10000/1000000)

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00001111])

Address += 1

time.sleep(10000/1000000)

#Turn off power

spi.xfer([MCP23S17_WRITE_01, GPIOB, 0b00000111])

Unlock Code 8088 assembly

ORG 0X0000

;Setup 8255

MOV AL, 0X80 ;MODE 2 PORT B OUTPUT

OUT 0X63, AL ;WRITE TO 8255 COMMAND PORT

MOV AL, 0XAA ;WRITES 0XAA TO PORT 0X60

OUT 0X60, AL ;

MOV AX, 0XF000 ;SET UP DATA SEGMENT

MOV DS, AX ;

MOV BYTE [0X5555], 0XAA ;UNLOCK BYTES

MOV BYTE [0X2AAA], 0X55 ;

MOV BYTE [0X5555], 0X80 ;

MOV BYTE [0X5555], 0XAA ;

MOV BYTE [0X2AAA], 0X55 ;

MOV BYTE [0X5555], 0X20 ;

MOV BYTE [0X7FF0], 0X20 ;LEAVES A MARKER IN THE END OF THE ROM

HLT