How fast is Radio Shack's 1976 (EDIT: 1985!) Science Fair Microcomputer Trainer?
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- Опубліковано 15 жов 2024
- UPDATE: MEA CULPA, GUYS - I just learned from Jason (a Science Fair Microcomputer Trainer expert) that this trainer did debut in the 1985 Radio Shack catalog, and NOT in 1976 as erroneously stated (I had found the 1976 date on the web, but it is wrong).
See here for the 1985 debut:
web.archive.or...
That makes the trainer much less "pioneering" than I thought, and the credit actually has to go to our beloved Busch Microtronic for being the first! The Science Fair is actually a clone (copy, re-implementation) of the Japanese Gakken FX Computer R-165, which was later re-released as the Gakken GMC-4 (in 2009). I knew about the Gakken machines, but I thought they were re-implementations of the Science Fair trainer, not the other way around. Thanks much for setting this straight, Jason - I'll also comment on this inaccuracy in my next video about the Science Fair trainer.
This of course does not invalidate the main point of the video, which was measuring the performance and demoing this nevertheless interesting trainer.
ORIGINAL, inaccurate description of the video:
The 1976 (!) Science Fair Microcomputer Trainer was the first of its kind - I think it is fair to say that Radio Shack were the first that successfully commercialized, if not invented, the concept of microcontroller-powered educational computer systems for kids and juveniles (for historic reference, recall that the Apple I was also introduced in 1976). When I got my hands on this NOS mint Science Fair trainer (it was still sealed in its box!), I was eager to learn how it compares to the competition in terms of processing speed. In particular, how it compares to the 1981 Busch Microtronic Computer System from 1981 (West Germany) that runs on the bigger brother of the TI TMS1100 microcontroller used in the Science Fair, the TMS1600. Both are 4bit MCUs - the Science Fair runs at 400 kHz, the Busch Microtronic at 500 kHz.
I think you misread the frequency. It’s 218,000 and the comma is the thousand separator. To quote Wikipedia:
Each instruction took between 10 and 15 microseconds to execute on the NMOS and PMOS parts
This comes out to at least 66,666 (sixty six thousand) operations per second assuming 15us instruction time. The address bus will be toggled even higher as the fetching of instructions probably also shows up there.
No way... remember, this TMS1100 is running a quite complex emulator.... what we are measuring is emulation speed. The address bus is also an emulated virtual address bus aimed at debugging, part of the monitor firmware program. Not a real addresses bus. In fact, the TMS series doesn't even have an (external) address bus, as it supported no external memory!
@@michaelwessel4953Ah! I see. So the ROM is running an interpreter... Okay, that makes sense.
@@root42 right... simple but effective... forcing kids to learn real TMS1100 machine language would have been torture 😋
@@michaelwessel4953 This is correct. The TMS1100 takes 6 clocks to execute an instruction. Therefore, the virtual machine within the SFMT is executing one virtual instruction every ~170 TMS instructions.
@@root42Yup, the TMS1000 is a Harvard architecture device, so the SFMT has be implemented as an interpreting emulator, as there is no way to execute native code, for example your program, from RAM.
The virtual machine and monitor within the SFMT code is implemented in about 1K (the other 1K of memory is used for the 6 built in games). It's really very impressive when you look at the disassembly. Although the TMS1100 has 128 nibbles of RAM, only 80 are available for you program code. There rest is used for the internal state of the virtual machine. 16 nibbles are used for the data memory available to your code. 10 nibbles are reserved for the virtual machine registers and the rest is used to record state like key presses, hex output values etc.
Oh, the monitor code is available? Where?
EDIT: found it: www.seanriddle.com/tms1100.html
I had that ! Loved that thing. It unfortunately got wrecked by my kids over the years. I still have all the old 100 and 200 in 1 kits in good shape.
Great little machine!
I never knew about that kit. I had the 150.and 200 project kits for basic electronics. I would REALLY have loved this one!
Have a look on eBay, sometimes they crop up! I was even lucky enough to find my NOS on Amazon!
nice!..great condition for such an old bit of gear!...i had one of the 80s Tandy electronics kit..got alot of use...i woulda loved one of these microcomputer trainers
..i found a very old electronics kit from the 60s on the side of the road...
I just found one today at a thrift store for $5 !!
I'm so excited!!
Excellent! Enjoy!
Pretty sure this entire video was spoken in a single run-on sentence. No wonder the Germans get so much more done in a day than us lazy Americans.