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All Kinds of Stuff

First, we’re watching the TV a lot hoping for the best for Florida.  My family enjoys vacationing each year in Marco Island, which seems to be exactly where Irma is heading.  A number of our friends got out of the state in time so we’re hoping they’ll be able to return home to find little damage.

Next week my son goes to college which means I’ll be pretty much gone all next weekend and most likely doing final preparations this week during the evenings.  There might be little accomplished here for the next week in terms of Corsham Tech projects but I will do my best to answer emails.

VCF Midwest (just west of Chicago) is happening this weekend.  Normally I’d be there but my new full-time job is keeping me busy and I just didn’t want to miss a couple days of work.  Yes, I really enjoy what I do for a full-time job, which is writing embedded software.

KIM Clone status… I spent the last two weeks chasing a “software” problem and the finally realizing last night that my design was right for a 6502 but had a slight error for using a 65C02.  Once the fix was applied the 65C02 worked perfectly.  The design has been updated to accommodate either chip.  My plan is to ship with a 65C02 but all of my code is written for the 6502 so it will work with either chip.  There is one annoying problem that I know how to fix but just didn’t have time yet to address: the FT232RL backfeeds power into the main circuit, and it’ll take a couple more surface mount parts to fix.  The other outstanding hardware problem is that single step doesn’t work; it appears that a single jumper might fix it.

That’s enough for now… there is work to be done!


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This board is targeted to 6809 based systems which have a 4K EPROM window from F000 to FFFF.  By default, the EEPROMs included with all our systems are 8K (28C64) because it’s easier for me to stock one EEPROM instead of multiple ones.  The lower 4K is not accessible, and SBUG is in the top 4K.

As some of you know, we’ve been looking at getting a port of OS/9 and while working with the OS/9 experts it was decided that a custom EPROM image with most of OS/9 in it would be a better solution that have 4K of SBUG and then using a lot of RAM for the OS.  I didn’t want to make a customer choose between flashing either OS/9 or SBUG, so it was suggested to make a small add-on board with DIP switches to select which image to load.

Here is that board:

SW1 controls A12 and SW2 controls A13, so by setting them appropriately and with the right size EPROM, this board allows up to four boot images to be in memory from E000 to FFFF.  Since I use 8K EEPROMs, only two images are available, but a customer can also use a 28C128 which allows four images.

The price for this board assembled and tested without an EEPROM is $20.  Kit is $15, and a bare board for $10.  Free shipping in the US, of course.

I can hear your next question: “So is OS/9 available?”

No, but extremely close.  Boisy Pitre and I worked at VCF SE and made a lot of progress.  I made changes to the EEPROM code and Arduino code, as well as to the motherboard to allow everything to work.  He did all the code changes in NitrOS/9 to support the Corsham Tech boards.  I’ve had a preliminary version running for about a month now and it’s very nice.  Boisy is working to get the changes into the official distribution and then it will be available.  In the picture above, SW1 selects SBUG or NitrOS/9 boot… ON is Flex, OFF is NitrOS/9.

Close, very close.


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VCF SE 5 Summary

I made it back without a car crash (I totaled my BMW going to VCF East a few years ago), despite the 816 mile drive in each direction!  It was a good show, definitely well done.  My exhibit was pretty much the same as other recent VCFs but they did provide the commercial folks with a bit more table space so we had a nice “work area” just to the right of my display that we all shared for working with people.

If you’ve never been to a VCF, they aren’t big commercial displays.  Yes, a few commercial folks like me are there, but the whole atmosphere is about sharing ideas, showing off projects and meeting like-minded people.  Need a voltmeter?  Someone’s got one to loan.  Can’t remember the pin-out of a 7400 series device?  Someone has a databook to share.  It’s half about the technology, half about the comradery.  Go to local restaurants and there are fellow vintage computer people there… grab and seat and join in the conversation.

Roswell, GA was a 816 mile drive, but the hotel was nice and the show building was right across the street, plus quite a few restaurants within easy walking distance.

I never take a lot of photos, but here they are:

One of the key topics for me was to talk with Boisy Pitre about porting NitrOS/9 to the Corsham Tech 6809 system.  He got it partially booting before we found my SD card sector read/write routines weren’t a good solution, so he took a system and I’m in the process of coming out with a new EPROM and new Arduino code to make the portation much easier.  I should get the new code to him this week.  My code was heavily based around what Flex/9 needed but those routines were clunky and limited disk sizes for other OSes.  BTW, this might shake out some problems in my boards that were never noticed before.  I already found problems in the rev 3 and rev 4 SS-50 motherboards that prevent IRQ, FIRQ and IRQ from working.  SWTPC never used interrupts so I didn’t test them since rev 2 motherboards (which don’t have the bug).

Another great discussion was with Mike Lee from the Chicago area about a possible new project that I had considered and partially designed but never finished.  It’s KIM related but that’s all I can offer for now.

Anyway, I got in the car around 4 PM Sunday and drove straight through the night, climbed into bed around 5:30 this morning for a few hours of sleep and need to finish unpacking the car still.  It was a fun weekend, lots of driving, lots of vintage computing, lots of great discussions, some excellent meals, and fun meeting up with people from around the world that I don’t see except at VCFs.

It’s time for a nap.