Month: February 2019

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KIM Clone Motherboard and Prototyping Board

These aren’t released yet as I’m still testing things out, but the motherboard and prototype board do exist.  This is part of the test/debug process where each signal gets checked:

The earlier version of the motherboard had some logic problems so this is a new version being tested.  Prior to it arriving, I had wired up a 6821 PIA (parallel ports) and was blinking an LED from the KIM Clone:

The proto board can plug directly into the KIM Clone or into the motherboard.  The motherboard has a limited amount of 5 volts available, enough for a few chips, but the KIM Clone only provides 8 volts.  That explains why there is a voltage regulator in the lower right corner.  For this particular board, the 6821 is mapped to the 14xx address space which is normally not used at all on a KIM-1.  The range 1400-16FF are undefined on the KIM, so it seemed like a good place to locate peripheral chips like the 6821.  The only part needed for decoding is a 74LS 138, unless tighter decoding is desired.

 

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New KIM Clone!

After almost a year of on-again, off-again, development we finally have a new revision of the KIM Clone:

It has everything the previous versions have, but with a few improvements people have asked for (or I wanted):

  • Expansion bus connectors!  This was widely requested.  Includes most processor signals, address and data buses, along with bank decoding  lines.  This is intended to plug into either a prototype board (more on this later) or a motherboard (in the works).
  • More jumpers to enable/disable blocks of RAM from being decoded.  K1-K4 each have jumpers, and 8K blocks for the entire memory map have another set of jumpers.  This allows blocks to be disabled on-board, then mapped to a user-supplied circuit.
  • Power on reset.  Not a major feature, but I didn’t like having to press RS every time I turned on my KIM-1.
  • Power connector and the power switch moved to the top edge of the board.

Price is the same as before: $225 for assembled/tested, $60 for a “bare” board with all surface mount components and USB soldered.

Jumpers to enable portions of RAM:

Prototype Board?  Motherboard?

I have to add photos, but there is a prototype board already done.  It can plug into either the KIM Clone directly or into the motherboard.

The motherboard needs another spin to correct a few problems, but should be here in another few days.  It has complete buffering of signals and three “slots” for plugging in custom designed boards or our prototype board.