Month: October 2020

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First VCF Swap Meet – November 7th, Wall NJ

The Vintage Computer Federation, like many organizations, was unable to have their VCF East event in New Jersey (USA) this year due to COVID-19.  Instead, they are having a one day outdoor swap meet.  For us hams, this will be very much like a good old hamfest!  If this goes well it might become a yearly event.  It is outdoors and sellers are being socially distanced, so even in these uncertain times the organizers are doing a good job to keep everyone safe.  Wear a mask, obviously.

Details can be found on the first entry on this page:

http://vcfed.org/wp/

The event is in a parking lot between a couple of other buildings so the GPS coordinates on that page will direct you to the exact spot.

My plan was to have a small Corsham Tech exhibit but my doctors want me to avoid being around crowds still, so I’ll be there in spirit but not in person.

 

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Note Quite Ready but Close

I had started work on an SS-50 prototyping board a couple years ago, had a first revision made last year, but never quite got around to testing it until now…

One of the fixes in Rev 2 is that the pins on the female sockets along the bottom have the signal names on them.  This rev was mostly to see if the buffering enable/direction lines were pulled to the right state by default.  I’ve only tested it as a slave device, ie, memory but still need to build a CPU circuit on it to verify the bus drivers work properly there too.

Since you’re probably wondering what’s on my example above (and a messy example it is), the bottom solderless board has a 2K RAM on it with only four address lines connected to the 6116 RAM chip.  That’s enough to run RAM tests and run code from.  A 74LS159 decoder, a 74LS00 to invert a couple signals and form one signal to tell the proto board which direction to drive the data bus, and a 6116 RAM chip.

The top portion is potentially more interesting… it’s an MC6847 graphics chip (VDG) hard-wired to text mode, and hard-wired to display just the letter “A” on the entire screen.  The two transistors (old school 2N2222s in metal cans!) drive a gray-scale only composite signal to an Apple monitor.  No color circuit yet.  The next step is to hook the data lines to the RAM chip, then add a few 74LS157 muxes so the SS-50 bus and the VDG can both access the RAM.  Eventually a port needs to be added so the main processor can see when a horizontal or vertical retrace is taking place and only update the display during those times.

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Good Medical News

My Oncologist said my status was fantastic at yesterday’s appointment.  The new immune system which has rebuilt itself after the bone marrow transplant has reducing the cancer to the point where it is no longer detectable in my blood stream, which is exactly what was hoped for.  I have a bone marrow biopsy scheduled in two weeks to determine if there is still some cancer left in the marrow if the immune system has really gotten rid of it all or if more treatments are still necessary.

Another interesting side effect is that my type 1 diabetes has been changing.  50 years of experience allowed me to manage my insulin injections purely on instincts, but lately I was running consistently low blood sugar and had to keep reducing the amount of insulin and when.  The oncologist said this is fairly normal as the new DNA from the donated stem cells (from my sister) are rebuilding my system and fixing some of the broken parts as it does its job.  So the digestive system is probably doing a better job digesting sugars and my pancreas is likely to be making insulin and trying to regulate glucose levels in the blood stream by itself.  From my perspective I’m simply taking less insulin per injection, fewer injections, and am having a much easier time maintaining a proper glucose level.

I am feeling much better and am more optimistic now.  Over the last few months I have been cleaning up the workshop, getting rid of old projects that I probably will never finish, and have focused on finishing up other projects.  Quite a bit of equipment, parts, and hobby items have been sold off or donated to computer museums.  The workshop is cleaner now than it has been in decades!