I had a fairly elaborate WIKI dedicated to my Superproto card, but either an upgrade of some underlying support application broke it or it was hacked. After making an effort to recover it, I decided to put up a basic HTML based page which shouldn’t suffer from that sort of issue in the future. Unfortunately, I don’t have time to recreate a lot of the detailed content regarding usage and applications.
Anyway the new HTML based page can be found at: www.willegal.net/superproto/SuperProto.htm.
Although I seldom put up blog posts concerning my tropical fish, I have been keeping tropical fish almost continuously since I was in junior high school. For the last few years, I have been maintaining a school of Convicts (Amatitlania nigrofasciata). A group of them inhabit a 55 gallon tank and I have another 10 gallon tank that I occasionally set up for breeding. That 55 gallon tank is too crowded for successful breeding. As I occasionally lose a fish, I keep an eye on the population in case numbers get too low. Lately I have been concerned about the number of females left in the 55 gallon tank, so I figured I should set up the spawning tank.
I put a female alone in the tank and adjusted the temperature to the mid 70’s. After about a week I added a similar sized male. That was something like 2 weeks ago and now we have had a spawning. That is about all it takes to get Convicts to spawn. You do have to keep an eye on the males, as when put in isolation with a single female, they can get tough on the female, but that is about the only thing to watch out for. In groups, this problem doesn’t appear as much, as the males tend to spend a lot of energy squabbling among themselves.
The Convicts have become one of my favorite species. They are hardy, not skittish and are extremely easy to breed. They have the typical Cichlid spawning behavior which is so much fun to watch. In my experience they are no more aggressive than other similarly sized Cichlids.
A great fish for everyone, from beginners on up.
I managed to test the version of MCMON for Digital Group Video card on real hardware, but there was a bit of drama involved. I started seeing corrupted characters when running Hangman with this card. From the beginning it looked like a memory issue.
First, I ruled out the problem being in the SCLEBI system memory by stopping the program and examining the local copy of the video buffer which looked correct. Then I took some time to isolate exactly what was wrong with the Digital Group Video Card memory. After closely examining the symptoms and running some simple tests, I determined that the most significant bit of video memory had a problem with adjacent locations. In other words, if I wrote MSB of address 0 to zero or one, then MSB of address 1 would also change to the same value. Same thing happened when writing to address 1. This was true of all pairs of memory locations where the upper six address bits (of seven) were the same.
The problem was finally tracked down to a pin that wasn’t soldered which left this address line floating. This turned the 256 bit SRAM chip in that location into a 128 bit chip. Adjacent memory locations were sharing the same data in this chip, accounting for the error.
I didn’t see this problem when testing a full array of characters displayed on the screen or when running MCMON because in those cases all adjacent characters share the same value of the MSB.
With this problem resolved, I was able to verify that Hangman with Digital Group video drivers worked correctly. This software can now be downloaded from my 8008 application page.
My MCMON (8008 mini-monitor) with Digital Group Video support can be downloaded from my MCMON page.
This is version 3.1 of the OS/X SCELBI app and can be downloaded from the usual page.
There is only one change in this version. It turns out that when 0xFF is written to it, the actual Digital Group Video hardware, sets the address to 255 and writes 0xFF to memory. The old version of my app just set the address of video memory to 0x0 and did not do the write. I found the discrepancy when testing a new Video MCMON monitor with real hardware.
This leads to a bunch of new stuff that I will be making available over the coming weeks. I will be adding this new DG video version of MCMON to my MCMON download page.
I also have a DG video version of Hangman that just needs final testing on real hardware. This is going to make a great display for the next VCF event that I manage to make it to.
I have crafted a minimal SCELBI cassette read program that is small enough that it can entered in a few minutes with MCMON. This will allow loading of larger programs into the 4K SCELBI-8H, without undo trouble or assistance of another computer. I actually created this a long time ago, but don’t think I ever put it up for download. Going forward, this is how I will be loading Hangman and other apps into my 8H.
By the way, I have to write about how proud I am of the OS/X SCELBI application. It really operates exactly like the real thing and with all the memory and peripheral options I have added, makes a great platform for checking out the 8008 microprocessor and hardware that was available in the mid 1970s.
With the emulated tape, I am able to completely test the process for typing in the tape read driver using MCMON and then loading hangman by tape. I still have to repeat the process on the real hardware, but the emulation has been so good in the past, that I don’t expect problems when repeated with real hardware.
I suppose I might have to build a DG cassette card, so I have more coverage of the available options from back in that day.
As far as the OS/X SCELBI app goes, I’ve started the process of putting the source up on git hub. I don’t know if anyone will take advantage of it, but it will eventually be made available.
Late last year, I wrote an essay about Steve Wozniak and the Apple 1 and Apple II. I think it might be a bit controversial in parts, as when Woz read a draft, he disagreed with a couple of the statements. I have been holding back on publishing, partly because I’m a little concerned about Woz’s comments, but I think it probably should be released anyway. I will take one more shot at editing it, before I put it out, but it’s already in pretty good shape.
Last, for those of you that are interested in the history of SCELBI or early micro-computers, I am working on a essay covering Nat Wadsworth’s life from the time he started SCELBI. Publicly available information on Nat Wadsworth is very limited. A few months ago, I conducted several extensive interviews with Terri Wadsworth, Nat’s widow. She was very open about their lives and provided a lot of insight into Nat Wadsworth’s personality and the history of SCELBI.
I need to follow up with a couple of additional interviews before I can complete this essay and would prefer to do this in person, so it will have to wait until the corona virus runs it course. I am sure that what I have already learned will be very exciting for people really interested in the early days of micro-computers. I just need to fill in a few blank spots before I feel I can release.
This version adds support for the Digital Group Video Board, as well as a ported MCMON monitor for the 8H that works with that interface. The following image is a screen shot of the app, showing the DG Video screen displaying an MCMON prompt.
This application is freely available for download from my web site.
I’m having a bit of trouble with the Apple Help system, but in case it is not working for you, you can also access the help pages from my web site.
The I/O port mapping for this emulator can be found on the Menu Options page of the help system.
The Digital Group Video Board interface for SCELBI has been one of the longest Vintage Computer projects I have been involved with. You wouldn’t think that fairly simple video card would involve so many different sub projects, but it has been quite an interesting challenge.
That said, I’m not quite done with it, as I still have to put together a nice demo application. That application is planned to be a port of SCELBI hangman. I have started flowcharting the video output software, but have a little ways yet to go.
The enigma of U.S. Grant is an ongoing puzzle to me and many other people. It’s hard to reconcile the failed farmer with the man who became the most successful general of the Civil War and afterward, the president of the United States.
I found this letter in the National Archives concerning a water tank constructed near General Grant’s headquarters at City Point. I think it sheds a little light into how Grant expected his soldiers to perform and perhaps a hint at why he was so successful as a general.
March 24th 1865
Mr McAlpine,
Dear Sir.
The General commanding directs me to inform you that the tank ordered placed by the well in front of these HeadQuarters, by Lieut. Genl. Grant is utterly worthless and a discredit to the mechanics engaged upon it and the person who superintended its erection.
He wishes you would send someone to look to as soon as possible to prevent its coming to pieces
Very Respectfully
Your Obt. Servt.
S M Schummaker
Captain — —-
Note that I’m not sure about the spelling of this captains name or his position at HQ. I also find the letterhead kind of interesting. There were so many different letterheads found in those few archives that I perused that I have contemplated trying to make a list of the varieties.
The final section of the MPS-10 gives some comparative cost estimates for several solutions. The comparisons are with a PDP-8/M.
http://www.willegal.net/blog/wp-content/uploads/2020/01/MPS-10-cost-performance.pdf
One interesting thing to note here is that the PDP-8/M solution, though it is more expensive, isn’t orders of magnitude more expensive. It seems to carry a 50% cost disadvantage.
So finally, here is the entire document in one PDF.
http://www.willegal.net/blog/wp-content/uploads/2020/02/logic-products-MPS-10-plan.pdf
Here is where this document really looks more like a product plan more than anything else. This section starts with a statement of availability of prototypes on March ’74 and production unit in June ’74. It follows with statements that no field service will be offered and a warranty period of 90 days. The lack of field service is due to the expectation that the customer will be technically capable, the relatively low cost of the product and high cost of field service contracts.
The next page contains a product promotion and support plan. It mentions several trade magazines, was well as a direct mail campaign. I checked several of the periodicals mentioned and couldn’t find any relevant MPS-10 ads, so I don’t know if they came out later or exactly what happened.
The documentation plan is mentioned, as well as some trade shows.
Given this extensive marketing plan, it is somewhat surprising that so little is known of the MPS-10 today.
The competition section might be the most interesting to vintage computer hobbyist. Among other architectures, the National IMP16 series is mentioned. The IMP16 is classified as a microprogrammed machine, rather than a fixed instruction set, as the 8008 and 8080 and a few others are classified as.
On the next page are listed a number of competitive systems made up from the previously listed microprocessors. Except for the the Microl and Sim-8, most of these systems are little known by the vintage computer hobbyist of today.
There is a chart showing features of the various systems, including the all important development tool support. This section is definitely worth review by the vintage computer hobbyist.
http://www.willegal.net/blog/wp-content/uploads/2020/01/Pages-from-MPS-10-marketing-plan.pdf
The lettering on the front is made with water slide decals printed with a laser printer. After applying, several coats of satin lacquer were sprayed on to protect the lettering.
There is only one edge connector for this double wide card. I decided this wasn’t enough support so I added those red blocks seen towards the bottom of this image. The small card on the upper left hand corner is used to latch the SCELBI output.
In a way, this is a project that doesn’t want to end. I still have to get some kind of demo application going and update my OS/X emulator to support this card. I’ll probably do the later, first, as it is easier to debug with the emulator than on the real system.
The page on performance starts by with a quick outline of the capabilities of an 8008 microprocessor. It then details timing of handling interrupts, the UART and external events.
The software page outlines some more of the basic implementation of the 8008, and outlines available tools. The user is expected to use a teletype and a PDP-8 during software development. There is a loader program that will reside in the M7342 Monitor/Control Module ROM.
The diagnostic page highlights available diagnostic capability of the MPS-10 which include PROM and RAM based diagnostics. There is also a section that specifies documentation that will be available. There will be both a hardware and software section in the user documentation.
The final part of this section includes note that says data sheets and product brochures will be available. This section seems just like a program plan, rather than end user documentation.