Based on a question on the 6502 CPU Family page on Facebook, I’ve added a bare board with EPROM order option. This includes a bare board (but with the USB interface completely installed) as well as the two EPROMs (well, one EPROM, one EEPROM) programmed with the latest version of the code.
The price for a bare board is $50, but the price of the board with the two EPROMs is $60.
I hope everyone had a very nice holiday season, although there are still a few days left before New Years Day, then everyone is back to their normal lives once again. My kids are getting older so Christmas iss not quite as exciting as past years but it was nice having my son home from college, having fun with his sister again. I definitely ate way too much, as usual.
Over the break I worked on some personal fun projects, like the Tiny BASIC interpreter, which is working quite nicely now. It will eventually be added to the KIM Clone monitor.
Speaking of the KIM Clone, I now have enough boards in stock that bare boards are being offered for sale. The “bare” board actually has almost all of the USB serial interface pre-installed and tested, so there are no surface mount components that need to be installed.
A few product is an SS-30 prototyping board shaped to work in both our motherboard as well as a SWTPC chassis. A picture is needed; I will get it posted later this week.
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.