The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Chapter 4
Figure 4-2. Pinout for 8K EEPROM.
commands verify each byte after programming it, so the inverted data automatically keeps
BASIC-52 from programming another byte until the EEPROM is ready to receive it.
Other EEPROMs have a busy output, usually at pin 1, which goes low when the EEPROM
is busy. For this type, you can tie the busy output to pin 12 of U1. BASIC-52’s programming
commands wait for a high logic level at this pin after programming each byte. Note that
this means that pin 12 of the 8052-BASIC must be high (or not connected) during
programming of any device. However, using the BUSY output is optional, since programming
won’t continue until the programmed byte verifies.
Whether you choose EEPROM or NVRAM, be sure to ask for a data sheet for the device
you buy, so you can verify its pinout, capacity, and timing characteristics.
Adding NVRAM or EEPROM
Figure 4-3 shows the added circuits for the NVRAM or EEPROM at U8. Because the circuits
are an addition to Figure 3-1’s circuits, the parts continue the same numbering sequence,
beginning with U8. AND gate U3C is the third gate of Figure 3-1’s U3. Table 4-1 is a parts
list of the components needed to add Figure 4-3’s circuits to Figure 3-1.
50 The Microcontroller Idea Book