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> Agon light™ 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 implemente

> Agon light™ 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 4y ago
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 4y ago
  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!
  - justin66 4y ago
    The ironic thing is, if this were 1980 and anyone were taking this thing's "fastest" designation seriously, the very first step z80 developers would take would be to figure out how to use the ESP32 as a coprocessor for general computation.
II2II 4y ago
We are also talking about a product that is directed towards people interested in 8-bit computers, machines from an era where custom chips were somewhat less common (at least towards the start of that era). If their customers are looking for a computer that operates in terms they understand, an FPGA is basically a non-starter. Also worth considering is that the CPUs themselves are often still available, so what is the incentive to stuff the CPU into an FPGA? Video chips are more difficult to come by, so many projects have to make some sort of compromise.
- justin66 4y ago
  > If their customers are looking for a computer that operates in terms they understand, an FPGA is basically a non-starter. I'm certain that anyone capable of really understanding the operation of an 8-bit machine without an FPGA is capable of understanding the operation of one with an FPGA. There are tools for programming an FPGA that someone who previously assembled their own boards might not want to learn about, but it's not like they're going to be baffled by them. I think what's happening here is people want to make and use something with period-correct physical parts for purely aesthetic, nostalgic reasons. I really think that is fine, it's the strangely inaccurate way some people refer to FPGAs that is irksome. > Video chips are more difficult to come by, so many projects have to make some sort of compromise. This use of the word "compromise" illustrates the priority aesthetics takes in these projects. The video chip based on a modern microcontroller isn't really the compromise, in engineering terms the fact that you're not using a board with fewer parts and lower power consumption that emulates a z80 on that microcontroller (or something) is the compromise. > Also worth considering is that the CPUs themselves are often still available, so what is the incentive to stuff the CPU into an FPGA? Potential ability to make a CPU with a higher clock rate and a board with fewer parts, and all the other reasons you'd use an FPGA.
zokier 4y ago
It feels especially silly when it has modern 240 MHz ESP32 instead on-board, as if it is somehow more authentic than a FPGA.
- musicale 4y ago
  Presumably you could do a cycle-accurate EZ80 implementation on the ESP32 as well. If the cycle timing and user-facing I/O pins are the same, the main differences resulting from implementation would presumably be in areas like form factor and power dissipation. I'm sure I've seen ESP32-based emulators running CP/M (or DOS for that matter) discussed on HN and elsewhere.
nullc 4y ago
The better thing to promote would be power efficiency-- an FPGA implemented micro-controller is not going to run on nanoamps of power. (and also better highlights why this chip is ??? ... as it has a 240MHz ESP on board. Why not forget about the 8bit microcontroller and just use the ESP? :) )
Brian_K_White 4y ago
It's just another form of emulation. If all you want is the functionality, and don't care how it works, then why in the world even bother emulating, or implimenting, a z80 with an fpga? Either use emulation software if you just want the experience, or just use normal contemporary hardware and software with no vintage aspect. Are you actually running a z80 to run a spreadsheet for actual productivity? Of course not. So you must be using a z80 for some other reason than it's actual functionality. So, the works matter after all. Pointful uses of an fpga wrt to vintage stuff is replicating parts that can't be purchased any more, or as a rapid development environment, emulating a system so you can develop some other hardware or software for that system etc. Emulating a cpu or a system which still exists, just to use it? Pointless. Any justification mentioning availability, size, cost, reliability, convenience etc, are even 10 or 100x better served by pure software. The amount of cases where the ultra cycle accuracy matters these days is actually quite small as both the emulator software and the contemporary cpus have gotten better while the target has not gotten any harder. Yes, a cpu implemented on an fpga is somehow not real, It's more real than pure software, but it's still essentially pointless in most cases, because it serves neither the "I just want the experience" as efficiently as pure software, nor the "I want to run the original hardware" at all, not merely less efficiently.
- justin66 4y ago
  > It's just another form of emulation. Arguing that a z80 implemented on an FPGA is an "emulated" z80 is as nonsensical as arguing that the Agon's new ez80 running in compatibility mode is an "emulated" z80. > a cpu implemented on an fpga is somehow not real, It's more real than pure software, but it's still essentially pointless in most cases, because it serves neither the "I just want the experience" as efficiently as pure software, nor the "I want to run the original hardware" at all The ez80 included with the Agon light was introduced to the market during the George W Bush presidency. That board is all surface-mount electronics with nothing upgradeable or easily repairable on it. It is cool and fun but it's not "the experience" or "the original hardware." (it is its own thing, and that's cool) > not merely less efficiently I'm not an EE but it seems to me the "efficiency" you're talking about here does not involve dollar cost, parts count, or electrical current, so that's interesting.

> Agon light™ 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 4y ago

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 4y ago
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!
- justin66 4y ago
  The ironic thing is, if this were 1980 and anyone were taking this thing's "fastest" designation seriously, the very first step z80 developers would take would be to figure out how to use the ESP32 as a coprocessor for general computation.

II2II 4y ago

We are also talking about a product that is directed towards people interested in 8-bit computers, machines from an era where custom chips were somewhat less common (at least towards the start of that era). If their customers are looking for a computer that operates in terms they understand, an FPGA is basically a non-starter. Also worth considering is that the CPUs themselves are often still available, so what is the incentive to stuff the CPU into an FPGA? Video chips are more difficult to come by, so many projects have to make some sort of compromise.

justin66 4y ago
> If their customers are looking for a computer that operates in terms they understand, an FPGA is basically a non-starter. I'm certain that anyone capable of really understanding the operation of an 8-bit machine without an FPGA is capable of understanding the operation of one with an FPGA. There are tools for programming an FPGA that someone who previously assembled their own boards might not want to learn about, but it's not like they're going to be baffled by them. I think what's happening here is people want to make and use something with period-correct physical parts for purely aesthetic, nostalgic reasons. I really think that is fine, it's the strangely inaccurate way some people refer to FPGAs that is irksome. > Video chips are more difficult to come by, so many projects have to make some sort of compromise. This use of the word "compromise" illustrates the priority aesthetics takes in these projects. The video chip based on a modern microcontroller isn't really the compromise, in engineering terms the fact that you're not using a board with fewer parts and lower power consumption that emulates a z80 on that microcontroller (or something) is the compromise. > Also worth considering is that the CPUs themselves are often still available, so what is the incentive to stuff the CPU into an FPGA? Potential ability to make a CPU with a higher clock rate and a board with fewer parts, and all the other reasons you'd use an FPGA.

zokier 4y ago

It feels especially silly when it has modern 240 MHz ESP32 instead on-board, as if it is somehow more authentic than a FPGA.

musicale 4y ago
Presumably you could do a cycle-accurate EZ80 implementation on the ESP32 as well. If the cycle timing and user-facing I/O pins are the same, the main differences resulting from implementation would presumably be in areas like form factor and power dissipation. I'm sure I've seen ESP32-based emulators running CP/M (or DOS for that matter) discussed on HN and elsewhere.

nullc 4y ago

The better thing to promote would be power efficiency-- an FPGA implemented micro-controller is not going to run on nanoamps of power. (and also better highlights why this chip is ??? ... as it has a 240MHz ESP on board. Why not forget about the 8bit microcontroller and just use the ESP? :) )

Brian_K_White 4y ago

It's just another form of emulation. If all you want is the functionality, and don't care how it works, then why in the world even bother emulating, or implimenting, a z80 with an fpga? Either use emulation software if you just want the experience, or just use normal contemporary hardware and software with no vintage aspect. Are you actually running a z80 to run a spreadsheet for actual productivity? Of course not. So you must be using a z80 for some other reason than it's actual functionality. So, the works matter after all. Pointful uses of an fpga wrt to vintage stuff is replicating parts that can't be purchased any more, or as a rapid development environment, emulating a system so you can develop some other hardware or software for that system etc. Emulating a cpu or a system which still exists, just to use it? Pointless. Any justification mentioning availability, size, cost, reliability, convenience etc, are even 10 or 100x better served by pure software. The amount of cases where the ultra cycle accuracy matters these days is actually quite small as both the emulator software and the contemporary cpus have gotten better while the target has not gotten any harder. Yes, a cpu implemented on an fpga is somehow not real, It's more real than pure software, but it's still essentially pointless in most cases, because it serves neither the "I just want the experience" as efficiently as pure software, nor the "I want to run the original hardware" at all, not merely less efficiently.

justin66 4y ago
> It's just another form of emulation. Arguing that a z80 implemented on an FPGA is an "emulated" z80 is as nonsensical as arguing that the Agon's new ez80 running in compatibility mode is an "emulated" z80. > a cpu implemented on an fpga is somehow not real, It's more real than pure software, but it's still essentially pointless in most cases, because it serves neither the "I just want the experience" as efficiently as pure software, nor the "I want to run the original hardware" at all The ez80 included with the Agon light was introduced to the market during the George W Bush presidency. That board is all surface-mount electronics with nothing upgradeable or easily repairable on it. It is cool and fun but it's not "the experience" or "the original hardware." (it is its own thing, and that's cool) > not merely less efficiently I'm not an EE but it seems to me the "efficiency" you're talking about here does not involve dollar cost, parts count, or electrical current, so that's interesting.