Intel MCS-48

  • Intel
  • Philips Semiconductors
  • NEC
  • Siemens AG

MCS 48 is the name of a set of 1976 Intel family of 8 -bit microcontrollers. In a microcontroller in the optimal case, all parts of a computer system (processor, program memory, data storage and input-/output ) are combined in a single device. The MCS-48 series is one of the first such systems. At the beginning they had only three members with the designations 8048, 8035 and 8748 In 8035, the application is in an external module, whereas there is the application program in the block even when 8048 and 8748 -. Either in a mask-programmed ROM ( 8048 ) or in an EPROM ( 8748 ).

In 1980 was introduced with the introduction of the Intel 8051 a more powerful successor family, which was known as the MCS -51. The success of the 8048 series in many applications made ​​but that he was still used later massively and even in use today.

History and Use

In 1978, the "low-cost " versions 8020, 8021 and 8022 that had fewer connections and therefore could only be operated with internal program memory appeared. In the same year, the complementary module number UPI -41 (Universal Peripheral Interface) was presented. Here, the 8-bit data bus is directly led out, so that the processor can be used as a slave processor. Compared to 8048 with 96 commands has the 8041 90 commands. In the beginning, the series only of the two members with the designations 8041 and 8741, the most famous is probably the use of the later published 8042 featured as a keyboard controller in the 1984 IBM PC AT.

In 1978, the corresponding variants 8039 and 8049, the 8749 introduced in 1981, each with dual ROM and RAM.

The family was initially then manufactured in NMOS technology, from the beginning of the 1980s, in today's conventional CMOS technology.

Philips Semiconductors (now NXP) had a license to produce this family and has developed based on the architecture of their own MAB8400 family, which among other things the first I ² C interface and contained in the first Philips CD - players (eg CD -100) was used.

Also in the spread in the 1980s Genius Computer mice was a 8048 used, as well as a co- processor was also used in the Sinclair QL. Invisible are MCS -48 devices even today in a myriad of devices from the bedside clock to find a VCR to the washing machine.

Architecture

The MCS-48 series is basically constructed according to the Harvard architecture, where the program and data address space still is a separate Ein-/Ausgabeadressraum. The length of the program address is 12 bits, so 4 Kbytes can be addressed. These are organized as two independent 2- Kbyte program benches. Since bank 2 is always external ( except 8050 ), additional program memory can be addressed through the use of output lines.

The internal data memory ( 64 to 256 bytes ) can be extended externally by a further 256 bytes. The memory cells are made static, it can be powered by a standby supply line even when turned off with power and so obtain the data.

An extension of input-output lines takes place in the simplest case, the Portextender block 8243 that provides four 4-bit ports. Here is the 8243 integrated with specially designated commands in the overall system. In addition, standard can MCS-80/85 I / O modules are operated in the data address space.

During the development special attention was paid to a command set that provides powerful bit operations, on the other hand also as compact as possible. Most commands are only 1 byte long with implicit operands, a few have coded an operand in a second byte. This very short programs that are tailored to the given memory size arise.

A great disadvantage of the architecture was that only conditional jumps could be completely performed within a 256- byte page. This led to readjustment program extensions subsequent conditional jumps by the downstream direct long jumps, to overcome the 256 -byte page boundary, which subsequently led to further displacements code with corrections. Several interventions in the assembler code and subsequent assemblies were the result. During the subsequent MCS -51, this disadvantage was eliminated by the condition jumps relative ± 127 bytes could be carried out to the jump command and were not tied to page limits.

Common features of all MCS-48 modules:

  • 8-bit processor core
  • Min. 64 bytes of internal RAM
  • Optional external RAM and ROM
  • Interval timer
  • 2 interrupt sources

Variants

Known devices with MCS-48 blocks

  • Philips G7000 video game, as the main processor
  • Sinclair QL computer, as a coprocessor for peripheral
  • IMSAI 8048 Controll computer
  • Nintendo Donkey Kong game machine ( 8035 -clone MB8884 as sound CPU)
  • Cosmos CP1 learning computer
  • Entex Adventure Vision game console (1982 ) similarly Vectrex, but with red LEDs
  • Engine control unit Digijet VW Bus T3 ( 2.1 liter injection engine code: DJ)
  • Roland CR -78 drum machine (1978), working with a 8048
  • Korg Poly -61 Synthesizer (1982 ), working with two 8049
  • Korg Polysix Synthesizer (1981 ), working with a 8048 to 8049 as a parameter control and keyboard controller
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