Z8038018FSG Zilog, Z8038018FSG Datasheet - Page 49

• Manufacturer Part Number: Z8038018FSG
• Description: IC 16 BIT Z80 MPU 100-QFP
• Manufacturer: Zilog

Specifications of Z8038018FSG

• Processor Type: Z380
• Features: 16-Bit, High-Performance Enhanced Z80 CPU
• Speed: 18MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 100-QFP
• Processor Series: Z80380x
• Core: Z380
• Program Memory Size: 64 KB
• Maximum Clock Frequency: 18 MHz
• Operating Supply Voltage: 0 V to 5 V
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PS010002-0708
The size of the data element being addressed depends on the instruction being executed as
well as the Word/Long Word mode. A bit can be addressed by specifying a byte, and a bit
within that byte. Bits are numbered from right to left, with the least significant bit being bit
0 (Figure 35).
The address of a multiple-byte entity is the same as the address of the byte with the lowest
memory address in the entity. Multiple-byte entities can be stored beginning with either
even or odd memory addresses. A word (either 2-byte or 4-byte entity) is aligned if its
address is even; otherwise, it is unaligned. Multiple bus transactions, which may be
required to access multiple-byte entities, can be minimized if alignment is maintained.
The formats of multiple-byte data types are also shown in Figure 35. Note that when a
word is stored in memory, the least significant byte precedes the more significant byte of
the word, as in the Z80 CPU architecture. Also, the lower-addressed byte is present on the
upper byte of the external data bus.
Bits within a byte:
16-bit word at address n:
32-bit word at address n:
Memory addresses:
7
D7-0 (Least Significant Byte)
D15-8
D23-16
D31-24 (Most Significant Byte)
15
6
14
Even address (A0=0)
Least Significant Byte
Least Significant Byte
Most Significant Byte
5
Figure 35. Bit/Byte Ordering Conventions
13
4
12
3
11
2
10
1
9
0
8
7
Address n
Address n+1
Address n
Address n+1
Address n+2
Address n+3
6
Odd address (A0=1)
Most Significant Byte
5
4
3
2
Z380 Microprocessor
Product Specification
1
0
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