I am building an eeprom programmer for the 28C64A (dip package) with my old basic stamp ii "homework" board (lost my arduino in the move). I have the first four address and data pins, as well as W E and G connected from P0 to P10. I am working with what I already have, so buying shift registers and friends is not an option. My question is that I read over the eeproms datasheet and it said nothing about leaving unconnected pins floating, so is it okay to do that, or must they be grounded?
Floating EEPROM (28c64A) pins an option
eepromfloating-pinground
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First of all: Memory IC nomenclature is not robustly standardized; There is a lot of variation and even conflicting coding between manufacturers, on the order and meaning of the codes making up the part identifier.
That being said, here is an attempt at providing an overview:
The initial 2-digit code is the device family. A leading "24" indicates a I2C serially accessed EEPROM. Some other families are 95 (SPI serial EEPROM), Flash (e.g. 28F, 29F) and "standard" EEPROM (28).
Some manufacturers precede the 2 digits by a letter code, M for memory devices (STMicroelectronics, Atmel and others) optionally followed by an additional letter e.g. MX = Macronix memory.
Thus the device family becomes M24 for these examples.
The next letter or two usually indicates logic family / device voltage, but different manufacturers differ in their use of these codes:
- C = 5 Volts
- W = 2.7-3.6 Volts (sometimes 2.5 to 5.5 Volts)
- V = 3-3.6 Volts
- L = 4.5-5.5 Volts
- R = 1.8-5.5 Volts (typically STMicro)
- AA = 1.8-5.5 Volts (typically MicroChip)
- LC = 2.5-5.5 Volts
The digits after this do typically indicate memory capacity, but this is not simply the number of bits or bytes of memory. For instance, 512 = 512 Kilobits 8-bit EEPROM, but 516 = 512 Kilobits 16-bit EEPROM (usually, but not always!)
Some memory devices follow this up with a 2-digit access time code, i.e. access speed of the memory. Here again, 25 = 25 nanoseconds, but 10 = 100 nanoseconds usually.
This may be followed by a single or two-letter package indicator (B = Plastic DIP, N = TSOP, and a variety of other codes).
Last, a single-character (number or letter) device grade code may be added, i.e. various temperature ranges, military-grade, automobile grade, etc.
The only reliable way to interpret a particular memory IC's code, is to look it up in the datasheet, since there are wide variations, and even outright discrepancies, between manufacturers (and I suspect sometimes between production years too).
There are Application Notes for memory nomenclature by STM and several other manufacturers out there. Also, a fair guide to memory ICs, if somewhat incomplete, is here.
AFAIK Memories don't have an instruction set. Thy may have some commands to do a bulk erase or so.
In your case you have to know how big is your program/data and what addresses it will occupy.
You don't need a compiler. All you need is:
- Device programmer (physical hardware)
- Your data to be programmed in i-HEX format or
- Your data to be programmed in S-record format or
- Your data in binary format
Here are your answers taken from the device datasheet:
Edit: On second thoughts: you can build your own programmer as I did long time back using dip switches, de-bounce circuit, push-button for PGM and LOTS of TIME :)
Best Answer
Read the part about input current. Close to zero, right? It's a CMOS chip, so you must tie all the inputs to appropriate logic levels (high or low, depending on what you want).