Intel MCS-48 Introductory Information Page

MCS-48 Single Component System

First I must define some terms. In this system, a word is 8 bits (a byte). I will try to make sure that I don't use that term. However, if it shows up, you know what I mean. Unless otherwise noted, the details in this section apply to all versions.

Basics:

• 8-bit CPU
• 8035 uses external memory
• 8048 has a 1K mask programmed ROM
• 8748 has a 1K EPROM
• single 5 volt supply
• Over 90 instructions
• 64x8 RAM
• 27 I/O lines
• Interval time/event counter
• Expandable memory and I/O
• compatible with 8000 series peripherals
• Single level interrupt

Architecture:

The Arithmetic Logic Unit accepts 8 bit instructions/data. The instruction set allows for the following functions:

• Add with or without carry
• AND, OR, and Exclusive OR
• Increment/Decrement
• Bit Complement
• Rotate Left & Right
• Swap Nibbles
• BCD Decimal adjust

Memory:

Program Memory:

Memory is available as 1024, 2048, or 4096 bytes. The Program Counter is only 12 bits wide. However, only 11 bits of resolution are avaliable.

Data Memory:

Data Memory is organized as 64, 128, or 256 bytes in the 8048AH, 8049AH, and 8050AH.

Input/Output:

Ports 1 & 2:

Bus:

Test & INT:

PC & Stack:

PSW:

Interrupts:

Timer/Counter:

External Access Mode:

Sync Mode:

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last modified 11JUN04

this home page is maintained by Lowell O. Turner. Please email 4C2E54@gmail.com with comments and corrections.