I am having trouble time writing the EPROM chip, like the datasheet told me to have 12-13v connect to VPP while GVpp is on high, I add 8 more volts with button so 4.5 plus 8v is 12.5-13v(8-9v battery minus goes to ground, and plus goes to vpp). But the chip would not write. How do I get the chip to write?

Datasheet: https://media.digikey.com/pdf/Data%20Sheets/ST%20Microelectronics%20PDFS/M27C801.pdf

Schematics: https://prnt.sc/j4iqqp (Math mistake, 0.2 ohm suppose to be 0.5 ohm)

I tied 4-5v to vcc. But I didn't tie any address to high nor low which should have a default address to 0000000000000000000.

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    \$\begingroup\$ What convinces you that floating address lines -> zero address? Unless the datasheet guarantees built-in pulldowns or other measures, a floating input is invalid, doesn't have a well-defined function, and certainly cannot be guaranteed to result in address zero. \$\endgroup\$ – Andrey Akhmetov Apr 12 '18 at 22:47
  • \$\begingroup\$ A floating address would typically be all ones. There is no such thing as an invalid address, the bits are either high or low logic levels. Floating is normally considered high if there is any leakage current (here it's about 10uA) \$\endgroup\$ – Jack Creasey Apr 12 '18 at 23:08
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    \$\begingroup\$ Connecting 9V and 5V together like that doesn't give you 14V... \$\endgroup\$ – brhans Apr 12 '18 at 23:37
  • \$\begingroup\$ My battery is not exactly 9v, its 8-8.5v. But I'll tie all address to ground and see if this works. \$\endgroup\$ – Sup Boy Apr 13 '18 at 3:16
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    \$\begingroup\$ @SupBoy You also noticed that VCC is specified to be 6.25V ± 0.25V. when programming? Be kind and post your working answer to. \$\endgroup\$ – Dorian Apr 13 '18 at 12:13

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