DTK PIM Turbo XT Motherboard System Board Switch Settings

Unlike newer computers – I don’t know of an 8088 that has a CMOS setup program.  Instead the configuration was set by jumpers and switches. Here are the ones for DTK PIM Turbo.

The DIP Switch (SWI) is used to set the system configuration and specify the amount of memory installed on the main board.

The System Board Switch Settings

Position Function
1 : Normal Operation Off
2 : Off for 8087 not installed – ON of 8087 Installed

3 – 4 : Amount of System Memory
3 = Off 4 =On : 128K Installed
3 = On 4 = 4 Off : 192K Installed
3 = Off 4 = Off : 256K Installed

5 -6 : Type of Display Connected
5 = On 6 = On : No Display
5 = Off 6 = Off : Monochrome Display
5 = Off 6 = On :Color 40×25 Mode
5 = On 6 = Off : Color 80×25 Mode

7 – 8 : Diskette Drive Installed 5 1/4
7 = On 8 = On : 1 Drive
7 = Off 8 = On : 2 Drives
7 = On 8 = Off : 3 Drives
7 = Off 8 = Off : 4 Drives

 

DTK Configuration Switches

 

How to Change the System Board Memory (256KB/640KB)

If you want set TURBO-XT to 256KB then.
You must plug RAM Bank 0,1,2,3 full with 64K Dynamic 4164 chips.
or plug RAM Bank 0 full with 256K Dynamic 41256 chips.
And set JP3 and JP4 as indicated in the below table.

If you want set TURBO-XT to 640KB then.
You must plug RAM bank 0,1 full with 256K Dynamic 41256 RAM chip.
And plug bank 2,3 full with 64K Dynamic 4164 chips.
And set JP3, JP4 as following table.

 

DTK RAM Jumpers

 

RAM Banks

 

DTK Ram Jumper Location

The TURBO-XT Supports both software switch as well
as hardware switch to allow switching from Normal mode (4.77Mhz) to Turbo mode (8Mhz) and vice versa.

We are going to use the hardware version or switch.
TO do this – Set Jumper JP6 to ON
When JP5 is shorted or ON – The machine will operate at 8MHz
In the Off Position JP5 – The machine will operate at 4.77Mhz
A toggle switch can be installed from JP5 to enable and disable turbo mode.

JP9 is the power LED and Turbo Led indicator connector.

Pin 1 – Turbo LED
Pin 2 – Turbo LED
Pin 3 – LED Power
Pin 4 – Ground

 

DTK Turbo Switch

 

DTK Power and Turbo

 

If you are looking for the complete installation guide for DTK-PIM Turbo XT – the link is below.