I guess this is sort of on topic, certainly goes with the subject anyway. Back at the beginning of time when microprocessors had 1 MHz clocks and program and data storage was external to the processor, using more than one CPU in a system sometimes was vital rather than just an interesting thing to do. For example, in a data acquisition and processing system, to get the throughput necessary for success, one could have one CPU controlling data acquisition and buffering and another CPU handling computations and HMI. Since early microprocessors had external address and data busses and memory some interesting things were possible.
If the CPU clock was two phase, you could operate the CPUs off of opposite phases and therefore share the same physical program and data storage. Since many times there were functions that were common to both subsystems, sharing the program storage was an economical thing to do, as EPROMs were relatively expensive then. Data storage sharing was particularly compelling because it eliminated the interprocessor communication that would have slowed things down otherwise. A system of semaphores in shared R/W memory kept things synchronized and since the CPUs were on oposite phases of the clock, there was never any interference. Completely separate areas of program and data could also be maintained if that was desired.
Nowadays we just throw another $3 microcontroller at the problem.
Yeah, prices sure have dropped.
And now a 512K x 8 SRAM is $4.70
Maybe I'll make a 1M x 16 SRAM for capturing 24 second sound samples at CD quality.
4 chips, 3 8-bit counter chips, a couple of transceiver to mux the 2 bytes & store to SD card, 16 BIT DAC to play it back for a sound check ...
10cm x 10cm x 10 pieces, only $24.90 (plus shipping) - WOW.
They also supply an Eagle to Gerber conversion program (I have only ever used Eagle before).
Eagle exports Gerbers directly. Downloads itead's 'rules' file, it will provide the setup files needed so you can select in eagle files:export and have the file outputs needed created and check what you will be getting,
Many thanks CR - I will download that and give it a go, once I,ve designed my board.
Do I need both the .cam and .dru files?
How long did it take you take get your boards, once ordered?
(I know we will in different countries, but it may just give a ball park figure).
6800 at first and then mostly 6809 soon after. I really liked the 6809. All those address modes that worked for every instruction. Hated the 8080. You had to keep the fold-up card with all the opcodes with you all the time to check if you could use a particular address mode with a particular instruction. The Z80 was pretty nice.
The 68H16 was probably the cream of that crop. It's a shame it grew out of its DIP shoes. Made it hard to prototype with.
Graynomad:
Z80 gets my vote. Closely followed by the 68000 in the "aircraft carrier" package.
Rob
Yes, wasn't that an impressive package? That was a proper microprocessor with external busses and a package you could plug into a breadboard. I had one of those wire-wrap "bed of nails" proto boards that was just a huge XY grid of machined sockets with a 68008 on it.
Ok, the order I placed for 50 mini-uino's was accepted Aug 26, shipped Sept 1, tracking showed up in China customs Sept 4, arrived here Sept 15 (Boston, MA area).
Bobuino's were about same.
Back at the beginning of time when microprocessors had 1 MHz clocks and program and data storage was external to the processor, using more than one CPU in a system sometimes was vital rather than just an interesting thing to do. For example, in a data acquisition and processing system, to get the throughput necessary for success, one could have one CPU controlling data acquisition and buffering and another CPU handling computations and HMI. Since early microprocessors had external address and data busses and memory some interesting things were possible.
