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KIM Clones are available plus other news

I’ve stocked up on a lot of parts and can now build and keep KIM Clones in inventory ready to ship.  Depending on how many orders come in quickly, there might be some delay, but at this point assembled units are in stock.  Bare boards will probably be available next weekend.  No word on kits yet; writing an assembly manual is more difficult than actually building one!

There is a new SS-30 based product but I’ve yet to take pictures.  Sometime this week it’ll be announced.  Nothing major, but might be handy for those who like to experiment.

Fix for KIM Clone Single-Step Problem

Rev 1B and rev 2 boards have a problem where single-step mode does not work.  It works for old 6502s but not for newer ones nor 65C02.  The solution was very simple: add a .001 uf capacitor across U16 pins 7 and 8.  All assembled KIM Clones now have the modification and future revisions of the board will have the capacitor on the motherboard.

Fun in Spare Time

The last few weeks have been extremely busy at my day job, as I’m a Principal Engineer and we’re working hard to roll out a new product.  My time for Corsham Tech projects has been limited, but sometimes coming home and writing some 6502 assembly code is relaxing.  One of my development machines has two editor sessions open.  One has my Tiny BASIC interpreter which is based very much on the IL concept that was well documented in the first few issues of Dr Dobb’s Journal back in the mid 1970s.  The other is a KIM game that fits in the original 1K of RAM and uses just the seven segment LEDs and KIM keypad.  Yes, both are being developed on a KIM Clone but run on an original KIM too.  I’ve got two KIMs, two SYMs and one or two AIM-65s to test on.

The IL interpreter has been interesting because it made perfect sense back when I first looked at it, but the implementation has a lot of subtleties that the implementers figured out and I’m slowly discovering.  My IL includes a couple new instructions and uses more direct addresses rather than relative addressing.  The IL code for BASIC takes more space but allows for longer branches and takes less time to implement since no math has to be performed.

More Code for Future KIM Clone EPROM

There is a lot of empty space in the KIM Clone EPROM due to the removal of the cassette tape functions.  I added a couple games but there is still a lot of room (“a lot” is relative… we’re talking a total of 1K here).  Maybe I’ll put a 16 bit math package there; it can be called by the IL interpreter.  If i ever finish the game then it will be put in as well.


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Games in KIM Clone

I had lots of extra space in the two EPROMs, so Farmer Brown and Lunar Lander from The First Book of KIM were added.  One starts at 1800, the other at 1803.

Three-Button Procedure for Lunar Lander

Once the ship begins to drop, let the speed increase to 75 (the far right two digits will climb to 75).  Press 5.  Now just let it fall until 1000 feet, then press 8.  Yes, you’ll be approaching the ground really fast, but you’ll have time.  Once the speed drops to 5 or below, press 5.  Just coast down to a SAFE landing.

There are many other methods to land with minimal input, but this is the easiest for me to remember.


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KIM Clone is Available!

After many months, it’s finally available… in small quantities!  This takes a lot of time to build, and takes a lot of parts that are being ordered, so I’ll probably only be able to build/ship one or two units per week.

Assembled units are available in the shopping area.  These are initially using the rev 1B boards which are fully functional but have some silkscreen errors.  Ie, some of the text printed on the surface is not correct; this has nothing to do with functionality.  I stopped doing serial numbers years ago but have decided to start again.  This is board #3:

The keypad has nice buttons that click when pressed.  Getting custom printed keycaps was out of my price range, so these are standard caps with white/clear printed labels on top.  Getting those buttons labeled is the single most time consuming process to build a board.

The USB interface to the PC is along the top.  Earlier I mentioned silk screen errors, and here is one of them.  Below our URL should be “Version 1B” but it was put on the back side of the circuit board by mistake.