TK2000 FASTIDIO

TK2000 F.A.S.T.I.D.I.O.

DISCLAIMER

Any use of this project is under your own responsibility. You will be responsible of checking the correct construction and functionality of your board. By using this project You will agree that I cannot be held responsible if it will destroy any of your devices, damage your computer, burn down your house or whatever.

Sponsorship

This project is kindly sponsored by PCBWay. PCBWay specializes in manufacturing high-quality PCBs and makes them affordable to hobbyist and professionals alike.

The range of services they offer include PCB prototyping, assembly, instant quotes for your order, a verification process by a team of experts and an easy to use, hassle-free order process.

I'm grateful to PCBWay for the help in evolving and testing this project. You can order the currently released revisions of the board from them, see the link below!

Introduction

The F.A.S.T.I.D.I.O. (Fully Addressable Simple Twin Interface Digital I/O) is an expansion card for the TK2000 computer that provides two 6522 VIAs to the computer.

Using 6522, you gain timers, and 4 8-bit I/O ports that can be used, for example, to interface with gamepads, or SD cards. All the I/O ports are broken out to pin headers. Additionally, the address of each 6522 can be set independently (and either of the VIAs can be left out entirely).

This board is meant to be used in the TK2000 bus extender and is part of my project to build a set of cards for the TK2000 computer.

You can build yourself a TK2000 computer using files from this repo and following my build notes.

Support

If you wish to support me in building new hardware and software for old machines, throw a few euros in my direction via Ko-Fi ☕!

Hardware

The board was designed with KiCad EDA.

Bill of Materials

Note on ICs

I noticed that access timing might be a bit finicky in regard to the Φ2 clock coming from the TK2000.

Experimenting, I found I the best reliability installing a 330pF capacitor (there is a provision for such capacitor on the BUS Extender) between Φ2 and GND and bypassing U2.

Once U2 is bypassed, U3 is also no longer needed and can be left off the board. Since rev.3 onward, you can bypass U2 by soldering the jumpers behind U2 (solder side). On previous revisions (0 to 2), you need to bridge the data lines yourself, like this:

My advice is to actually avoid installing U2 and U3 altogether and bypass them: use them only if an additional transceiver on the bus is later found necessary.

Configuring the address

The address for the I/O ports can be changed by jumpering the VIA 1/VIA 2 headers to the middle row.

      C C C C C C C C
      0 0 0 0 0 0 0 0
      8 9 A B C D E F
	  x x x x x x x x
VIA 1 . . | . . . . .
      . . | | . . . .
VIA 2 . . . | . . . .
          ^ default for VIA 1
		    ^ default for VIA 2

Ordering the boards

You can order the board for this project at PCBWay and support me or download the gerbers and have them printed wherever you like!!!