[HN Gopher] The Agon light is the fastest 8-bit microcomputer
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The Agon light is the fastest 8-bit microcomputer
Author : unwind
Score : 48 points
Date : 2023-02-02 09:26 UTC (2 days ago)
(HTM) web link (www.thebyteattic.com)
(TXT) w3m dump (www.thebyteattic.com)
| Someone wrote:
| I wonder why they went for 18MHz. The TI-84 Plus CE has a 48MHz
| eZ80 (https://en.wikipedia.org/wiki/TI-84_Plus_series#TI-84_Plus_
| C...), so it faster parts exist. Is it difficult for hobbyists to
| design the PCB, etc for a 50MHz machine? Or at the faster parts
| hard/impossible to find nowadays?
| derefr wrote:
| > Is it difficult for hobbyists to design the PCB, etc for a
| 50MHz machine?
|
| My understanding is that, from 1MHz or so (like a 6502) through
| to about 10MHz (like an 8086), it's pretty easy to _prototype_
| a complete computer -- CPU wired to memory, IO, etc, and
| everything in tolerance to speak to one-another within the CPU
| 's half-clock sample rate -- with just discrete logic
| components (e.g. NOR DIPs to combine address lines to make
| chip-select pins, etc) on a breadboard.
|
| Get much faster than that, though, and those discrete logic
| chips start to add too much delay; so you start having to
| prototype directly for a PCB with surface-mount components,
| rather than ever having a breadboarding phase. Which sucks,
| because now you're having to send your design out to be printed
| and picked, and so your iteration speed is now 1/100th of what
| it would have been before.
| cmrdporcupine wrote:
| This is, I believe, why many designs back in the day used
| wire-wrap. A cleanly done wire wrap can apparently get quite
| clean signal and achieve high frequencies. The Atari ST and
| Amiga generation machines were prototyped this way, for e.g..
| For the ST, 8mhz memory bus but faster for the video shifter
| portions where the RAM was multiplexed between the CPU and
| the Shifter.
|
| http://www.bambi.net/atari/atari_st_prototype.html
|
| Unfortunately wire wrap sockets are very difficult and $$ to
| source these days. Which is too bad because it seems like a
| good halfway point between breadboarding and PCB.
|
| FWIW I've managed to managed to get clean DVI/HDMI output off
| FPGA on a breadboard, and I'm by no means talented in
| electronics.
| rootbear wrote:
| I was fascinated to learn that the Apollo Guidance Computer
| was wire-wrapped. A good wire-wrap is a very reliable and
| durable connection.
| rcxdude wrote:
| You can prototype with SMD and something like veroboard, but
| it is fiddly enough that it's rarely worthwhile for anything
| but the smaller circuits.
| duskwuff wrote:
| The processor in the TI-84 is a custom part built around an
| eZ80 IP core.
|
| There are faster 8-bit CPUs available off the shelf, though.
| Hell, Silicon Labs makes some 8051 microprocessors that'll run
| at up to 100 MHz.
| fortran77 wrote:
| There was a 24 MHz 16-bit microcontroller out in 1985 or so: The
| Fairchild 9445
|
| https://www.cpushack.com/2017/11/14/cpu-of-the-day-fairchild...
|
| It ran the Nova 4 instruction set. We were using it for a
| cutting-edge project: and all Digital Radio receiver, for EVLF
| communications to submarines in the 16 kHz range.
| SinePost wrote:
| The TI-84 Plus CE has a eZ80 at 48 MHz.[1]
|
| https://www.brownmath.com/ti83/diff8384.htm
| [deleted]
| justin66 wrote:
| > Agon light(tm) is a true 8-bit microcomputer in that there are
| no FPGAs and no emulation in it.
|
| It would be nice if people would stop pretending CPUs implemented
| on FPGAs are somehow not real.
| cmrdporcupine wrote:
| There's gotta be an academic graduate level anthropology thesis
| that could be written with the title _" What Is Real?: The
| Online 'Retro-Computing' Subculture and Its Search For
| Authenticity."_
|
| The whole "no FPGA" thing is kind of funny when you see people
| reach for microcontrollers to do their video display component,
| and those microcontrollers themselves often greatly outperform
| the main CPU. What's the major difference between dropping in
| an MCU vs an FPGA?
|
| Aside: A friend of mine has reimplemented the whole C64 VIC-II
| VDP in Verilog ("VIC-II Kawari") complete with a test harness
| built around VICE, etc, amazing work; it would be so cool to
| see someone pony up the cash to get something like that fabbed
| in fresh new silicon. Then we could have a "true" retro video
| display controller so we can have a truly authentic neo-retro
| computer :-)
| sponaugle wrote:
| Indeed - I was surprised to see an ESP32 on there, driven
| over serial, for the video output. That seems an order of
| magnitude more modern than using a CPLD, much less an FPGA. I
| am building a VGA adapter for my 68k supercomputer using a
| CPLD which presents some challenges that would be easy to
| solve in an FPGA. I have wrestled with that concept of what
| is retro enough, and there is no simple answer. Sticking with
| thru-hole is hard enough given the ever declining
| availability of parts!
| shrubble wrote:
| They use an 18MHz eZ80 part. I have a 33MHz on its way to me now,
| except it is in a tiny 40mm square case and access is serial only
| over USB.
|
| I think it is this one:
| https://www.tindie.com/products/circlem/minz-c-small-cased-3...
| SV_BubbleTime wrote:
| I like that its 32bit audio and video co-processor is superior in
| almost everyway.
| LoveMortuus wrote:
| >Agon light(tm) is the fastest and cheapest 8-bit microcomputer
| ever made.
|
| But... The cheapest that I can see is about 50EUR... That doesn't
| sound very cheap to me :/
|
| Am I just lacking some information or is it actually not that
| cheap?
| mat_epice wrote:
| It's really a single-board computer, analogous an 8-bit
| Raspberry Pi. Not expensive for a SBC, but not as cheap as I
| would expect an 8-bit thing with vga would be.
|
| Being that 8-bit processors have been gone from interactive
| systems for so long, anything under a couple of hundred dollars
| would have been "cheapest." It would just have to come in under
| the price of the 80s systems. I could win the same kind of
| contest by making a 5-bit machine at any price!
| tyingq wrote:
| The "DUINOMITE" is 20EUR, but it's based on a 32 bit CPU, even
| though it sort of functions like an old 8-bit home
| computer...boots to a BASIC interpreter.
|
| Similar is the VGA+PS/2 equipped ESP32 board:
| https://www.aliexpress.us/item/2251832855287283.html at $12USD
| or so. But, again, not 8-bit.
|
| I think their claim of cheapest for this Agon light is because
| a 8-bit home-pc style computer is such a niche/purist space.
| It's more expensive to build a keyboard/vga ready thing because
| the chip doesn't have much built-in.
|
| https://www.olimex.com/Products/Duino/Duinomite/DUINOMITE/op...
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