The late 1970s were an interesting time for microcomputers. The rousing success of things like the 8080, the Z80, the 6800, and the 6502 made everyone wanted a piece of the action. National Semiconductor produced its SC/MP. That was technically the Simple Cost-effective Micro Processor, but it was commonly known as Scamp. There were several low-cost development boards built around this processor and [Hello World] is looking at Digikey’s “Nibbler” which was a fairly nice computer for only $150. Check it out in the video below.
The SC/MP was made to be cheap. It had a strange bank switching scheme reminiscent of the Microchip PIC 16F family. It also had, like a lot of old discrete computers, a serial ALU, which made it slower than many of its contemporaries. It did have good features, though. It was cheap and required very few extra parts along with a single 5 V supply in the second and subsequent versions. In addition, it had pins that were made for connecting more than one CPU, which was quite a feat for those days.
[Hello World] mentions that you don’t hear much about the SC/MP anymore and, in fact, we had all but forgotten about it. There is an effort underway to recreate the plucky little computer for anyone who wants to build a new one.
The $150 price tag seems reasonable, at least compared to other computers of the day. However, don’t forget that you still need a power supply, probably a card cage, and the biggest problem of all: a terminal. It is hard to remember how difficult it used to be to get your hands on a terminal at a reasonable cost. Your main choices were a TV typewriter or something surplus like a TeleType.
Oh so that’s what SC/MP stands for, thanks! Only 50+ years too late!
The absolute best that can be said of NatSemi’s ‘Scamp” attempt at a microprocessor (an 8-bit device which can’t address 64K? And that’s one of its better features) is contained in that homespun ‘side-ways’ compliment:
“For a fat person, you sure don’t sweat too much”.
It certainly didn’t do well, but it was hardly the only 8 bit CPU that had limitations on address space. The Motorola 680x comes to mind (e.g., 6801/6802, and some others). The F8, the 8048, the Z8, and some 1802 variants all had <64K of RAM. I would think the serial ALU was the real problem since, back then, you rarely had 64K of memory anyway until a little later when it got cheaper.
“…but it was hardly the only 8 bit CPU that had limitations on address space….The F8…had <64K of RAM…”
…Was an F8 designer.
The F8 had a 16-bit program counter (PC), and addressed 64K of RAM with either of the 3852 or 3853 memory controller chips (and the 3852 automatically refreshed DRAMS. In 1975, no less).
Concerning total memory addressing capability, the F8‘s16-bit PC says it all.
Regards…
Well maybe my memory is faulty but I worked on the insides of the 68xx and while we may have had a 16 bit PC in many of those, the wires were not bonded out. If I recall — and it is fuzzy — you had to have a separate thing to get the address bus out of the F8, no? If you only had a 3851 that was like 1K and a smattering of RAM. And, in that case, there was NO external address bus at all. You had to graduate to the bigger memory controllers because the PC was in the memory controller. Unless I am remembering wrong.
Anyway, my original point is still true: some of the CPUs of the era didn’t address 64K externally. Fast forward and the 68000 was the same way. It could address way more memory than it had external address lines in the early days.
What? The 6800, 6801, 6802, 6803, and 6809 were totally straightforward and usable and addressed 64K in a very straightforward way. Nothing daft like the 6502, 8048. Admittedly the 6805 was odd but still nothing as baffling as say the 8048.
This… ⇑
Absolutely.
I thought the “Nibbler” was a tool for the Apple ][ to duplicate copy-protected disks.
Lol! I thought the same thing!!!
Ox
That’s what I was expecting, too, especially with the visible card edge in the headline photo. I was expecting an Apple II (or Commodore) disk nibbler that happened to be based on the SC/MP.
The Nibbler was also a hole punch like device that allowed you to use the “other” side of your single-side 5 1/4 inch floppy.
There’s also sheet metal nibblers. And small ears of corn. And…
Don’t forget Lord Nibbler of Nibblonia https://futurama.fandom.com/wiki/Lord_Nibbler.
I thought it was going to be 4bit computer, a nibble.
I found an SC/MP kit unassembled in my father’s things. Not a nibbler as shown here. Beautiful white ceramic and gold.
Remember SC/MP well. And those other long gone uP’s.
I first found the Bank switching a little different, but with the PIC’s it didn’t take long to see the advantages, especially with frequently used registers.
Long live 8 bits!
The SC/MP’s 4k pages really were not a problem.
I had an evaluation board for a space hardened silicon-on-sapphire version of the SC/MP back in 1978. Had to build a case with power supply to house it and switches/LEDs to load/read memory a la PDP/11 style. Wrote a Morse code decoding program that output to an ASR33 Teletype as a PoC project. Couldn’t get past about 15wpm because of processor speed and the Teletype’s 110 baud interface, but fun to try in the early days…
I have always thought of it as scrimp.
Another thing National Semiconductor made that few remember was the Novus brand of calculators.