Here is the break down of the different areas of the DTK PIM Turbo 8088-2 Motherboard.

CPU Area – Power connector is the white connector on top.

Keyboard connector is just off the left.

The CPU is a FUJUTSU 8088-2 – Intel at one point licensed their CPU technology there were a few companies the produced some 8088 variants.

There is a socket for an 80887 Math Co-Processor.  The 80486 was the first of the x86 line to combine both in one package.


Project 8088 – DTK PIM Turbo Motherboard 8088-2 Components


The 8288 IC –  Pictured below was there so that the CPU can interface with the 8087 co-processor if present.  It was there so that the 8088 can operate in maximum mode.


Project 8088 – DTK PIM Turbo Motherboard 8088-2 Components


The 8284A was the clock generator for the 8088. The 8284 contains a clock generator capable of a third the frequency of the input clock (up to 8MHz with the 8284A), with sources selectable between an external crystal and clock input. The main clock output consists of a 4.5V (Vcc @ 5V) square wave at a 33.3% duty cycle, with an additional peripheral clock running at half of the main clock and a 50% duty cycle.

Something to note about the above – the 8088 operates at a 33.3% duty cycle. Thus the main reason for the 8284.

The DTK system board also has 8 – 8bit ISA slots.

Project 8088 – DTK PIM Turbo Motherboard 8088-2 Components


This board has a OTP (one time programmable) BIOS Chip. A 2764.  Which holds the 8K BIOS software for the system – there are 5 additional bios sockets.  In the IBM PC this would hold the ROM Basic.

Next to the BIOS Chip – is the 8253 which perform timing and counting functions using three 16-bit counters.

Below the 8253 is the 8259 a Programmable Interrupt Controller. The 8259 combines multiple interrupt input sources into a single interrupt output to the host microprocessor, extending the interrupt levels available in a system beyond the one or two levels found on the processor chip.


Project 8088 – DTK PIM Turbo Motherboard 8088-2 Components


Now the 640K of RAM held in 34 DRAM chips.  These can be identifed by the markings.. 41256, which 9 of them 1 chips is used for parity make up 256K – each chip holds 1 bit of the 8bit byte.  The 4164 are 64K versions.


Project 8088 – DTK PIM Turbo Motherboard 8088-2 Components


The 8088 system boards – at least the ones I have come across in my life – do not use a CMOS setup program.  Meaning the board configuration is not stored in CMOS and requires a battery.  You might find a battery on other boards – but this was mainly used for the real time clock.  Which was not present on any of the 8088 boards and I am aware of or have seen.

The board configuration is set by dip switches.

In the upper right is the 8255 Programmable Peripheral Interface (PPI) chip. The 8255 gives a CPU or digital system access to programmable parallel I/O. The 8255 has 24 input/output pins.

Below the 8255 is the 8237 DMA (direct memory access) Controller. It enables data transfer between memory and the I/O with reduced load on the system’s main processor by providing the memory with control signals and memory address information during the DMA transfer.

The 8237 is a four-channel device that can be expanded to include any number of DMA channel inputs. The 8237 is capable of DMA transfers at rates of up to 1.6 megabyte per second. Each channel is capable of addressing a full 64k-byte section of memory and can transfer up to 64k bytes with a single programming.


Project 8088 – DTK PIM Turbo Motherboard 8088-2 Components

Something You Might Be Intrested In


10F32X Rapid Prototype Board

Make The PIC10F322 and other PIC10F Processors Breadboard Friendly for Quick and Easy Prototyping.

{Click to learn more}

Project 8088 – DTK PIM Turbo Motherboard 8088-2 Components