Beta disk 128 interface clone with pass through connector.

Due to a problem with COVID-2019, delivery time may increase, please don’t buy if you can’t wait for more then 3-4-weeks. 

 

For sale Beta disk 128 interface ( BDI ) clone for any Sinclair ZX Spectrum.

Version 2.4 with pass through ZX-BUS connector. I have black and red versions.

You can use other expansion interfaces together with Beta disk interface.
All system lines pass through except IORQ  line - managed by beta disk interface.

 

Features:

1. BDI can be connected to the following models with some individual limitations:

Sinclair ZX Spectrum 48K

Sinclair ZX Spectrum + 48K

Sinclair ZX Spectrum + 128K

Sinclair ZX 128K Spectrum +2 gray

Sinclair ZX 128K Spectrum +2A/2B

Sinclair ZX 128K Spectrum +3

Harlequin ZX Spectrum clone ( Harlequin 128K internal Kempston joystick should be disabled ).

2. The BDI can be configured for use with any models with the help of five DIP switches.

3. There is one button traditionally called MAGIC, also used for run the built in test.

4. The BDI contains an FDC chip ( FDC1793 / KR1818VG93 / MB8877A ).

5. The BDI 64 KB of ROM. If necessary, the internal ROM of the controller can substitute the ROM of the computer.

6. Two floppy disk drives are supported

 

 Attaching the BDI

The BDI is inserted vertically into the ZX BUS connector.

 

ROM chip contain:

BASIC128 in the first quarter

It may contain any test for Spectrum that you like in the second quarter

BASIC48 in the third quarter

TR-DOS 5.04T in the fourth quarter

 

How to run the built-in test

The built-in test mentioned above is run in the following way:

Press the MAGIC button, hold it down and press the RESET button on the computer ( or turn it ON ). It is possible to exit the test mode only by pressing the RESET button on the computer.

 

The description of BDI switches

The BDI has a unit of five DIP switches (SW1 - SW5) and a jumper (JP1).

SW1

If it is ON, the ROM of the computer is substituted by the ROM built into the BDI.

If it is OFF, the native ROM of the computer is used.

SW2

It works only in the 48K mode. If it is ON, the computer is reset to TR-DOS. If it is OFF, the computer is reset to BASIC48.

SW3

If it is ON, the 48K model of the computer is used. The analysis of ports 7FFD and 1FFD is disabled.

If it is OFF, the 128K model of the computer is used.

SW4

If it is ON, the 128K model with a heat sink or the +2 gray model is used. The analysis of port 1FFD is disabled.

If it is OFF, the +2A/B (black) / +3 model is used

SW5

If it is ON, the BDI is disabled

If it is OFF, the BDI is enabled

 

Two pin jumper

Jumper should be removed for 48K models and inserted for +2A/+2B/+3 models.

It makes no difference for 128K models with a heat sink and for +2 gray models.

 

Using the BDI with a ZX Spectrum +3 computer

It is possible to work with the BDI in the full-featured mode only when the ROM of the computer is substituted with the ROM of the BDI (SW1 is ON).

In this case +3 ROM is switched off and +3 function and +3 disk drive dont support.

 

 

Postage with international tracking

 

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