The Macintosh SE was introduced in 1987 and marks an improvement over the Macintosh Plus. The SE was introduced at the same time as the Macintosh II. The main improvements were:
- An internal drive bay for a hard disk or a second floppy disk
- An expansion slot
- Standard SCSI connector and faster data throughput
- Cooling fan (prior models had no fan)
- Additional fonts and kerning in ROM
- Speed improvement when accessing RAM
THe Macintosh SE came with 1MByte of RAM, expandable to 4MByte. The processor was still the 68000 running at 8MHz. Graphics was 512x342 monochrome, which used 21888 bytes of main memory as video ram.
The expansion slot on the SE allwos for cards such as a MicroMac accelerator, which upgrades the SE to 50MHz. Putting an expansion card in the slot meant opening the case, which exposed the user to the high voltage that is present on a CRT, even when turned off, and Apple recommended that expansion was done by a qualified technician.
Motorola 68000 CPU Family
The Motorola 68000 is a 16/32-bit microprocessor that was first released in 1979. It was widely used in computers and other electronic devices during the 1980s and early 1990s. The 68000 was known for its advanced architecture, which included a 32-bit internal bus and a 24-bit address bus, allowing it to access up to 16 megabytes of memory. This made it more powerful than many other processors of its time, such as the Intel 8086 and Zilog Z80. It was also designed to be highly modular and expandable, with a large number of on-chip and off-chip peripherals.
Some of the most famous and successful computers that used the 68000 was the Commodore Amiga and the Atari ST, both of which were popular in the home and personal computer markets. Additionally, it was also used in workstations, such as the Sun 3 and Apollo DN3000, and in a wide variety of embedded systems and industrial control systems. The 68000 was also used in the Macintosh, the first model of the Macintosh was powered by a Motorola 68000 CPU. The processor was eventually succeeded by the 68020 and 68030, which offered improved performance and additional features.
The 68000 has a 32-bit instruction set, with 32-bit registers and a 16-bit internal data bus. The address bus is 24-bit and does not use memory segmentation, making it easier to address memory. There are three ALU's (Arithmetic Logic Unit), two for calculating addresses, and one for data, and the chip has a 16-bit external address bus.
The 68000 architecture was expanded with 32-bit ALUs, and caches. Here is a list with some 680x0 versions and their major improvements:
- 68010 - Virtual memory support
- 68020 - 32-bit ALU & Instruction Cache
- 68030 - On-Chip MMU, 2x 256 byte cache
- 68040 - 2x 4K Cache, 6 stage pipeline, FPU
- 68LC040 - No Floating Point Unit (FPU)
- 68060 - 2x 8K Cache, 10 stage pipelinet
Source: WikiPedia - Motorola 6800
Source: WikiPedia - 68000 Series