3 ms·

Here's this experiment sort-of running: WCH, which sells cheap mcu's(like $0.25 8051-mcu with usb/16Kflash) is working on a risc-V bluetooth mcu: https://www.

by petra 7y ago

Here's this experiment sort-of running: WCH, which sells cheap mcu's(like $0.25 8051-mcu with usb/16Kflash) is working on a risc-V bluetooth mcu: https://www.cnx-software.com/2019/02/16/wch-ch572-risc-v-mcu-bluetooth-le/ https://www.cnx-software.com/2019/02/16/wch-ch572-risc-v-mcu... And since risc-v has versions somewhere around 5K-10K gates, well, a lower end mcu isn't far, probably. Still, it would be interesting to think how we can get from that, to standard peripherals, and standard pinouts, used by at least 2 mcu makers. That would be interesting.

vardump 7y ago
> And since risc-v has versions somewhere around 5K-10K gates, well, a lower end mcu isn't far, probably. 5-10k? Seriously? That's amazing. Z80 had 8500. According to Wikipedia, even truly simple and bare bones 6502 had 3510 or 3218.
- petra 7y ago
  Smallest irsc-v core i know: https://devhub.io/repos/kammoh-picorv32 https://devhub.io/repos/kammoh-picorv32 ~1000 Luts. 1 Lut = 6-24 gates on average. a bit pmore but still pretty close.
  - vardump 7y ago
    A LUT can be 10 gates and it can be 100+ gates. You just can't compare FPGA LUTs to gates like that. FPGAs have things like block RAMs and multipliers. Those require a ton of gates, but don't increase required FPGA LUT count by much.
- deleted 7y ago
  [deleted]
- tasty_freeze 7y ago
  The Z80 had that many transistors, not gates The CMOS rule of thumb is one gate is 4 transistors (eg a 2-input NAND). But the first Z80 was nmos, and so the equivalent count is harder to state. 3 transistors per 2 input nmos gate is a rough first order guess, but in nmos wide gates still need only a single load resistor, and designers sometimes used dynamic logic to save even more transistors.
  - vardump 7y ago
    Ohh... This is embarrassing! I work in embedded/low level and I have always thought that gate == transistor. It's really obvious in retrospect... I stand corrected.
    - marshray 7y ago
      It's not a crazy idea, there are indeed logic types that implement some gate types with a single transistor. For example, https://en.wikipedia.org/wiki/Resistor–transistor_logic https://en.wikipedia.org/wiki/Resistor–transistor_logic These were more commonly used back when transistors were expensive.
- kragen 7y ago
  Designs like the GreenArrays F18A core show that you can do dramatically more than the 6502 or Z80 did in a similar number of transistors. The J1 and J1A are free descendants. The MOStek and Zilog hackers were wizards but they were working under serious time and, in the Zilog case, compatibility constraints. We know enough to do better now. (https://news.ycombinator.com/item?id=20688443 https://news.ycombinator.com/item?id=20688443 is on the same topic.) (As others commented, those are transistor counts.)

by petra 7y ago

vardump 7y ago

> And since risc-v has versions somewhere around 5K-10K gates, well, a lower end mcu isn't far, probably. 5-10k? Seriously? That's amazing. Z80 had 8500. According to Wikipedia, even truly simple and bare bones 6502 had 3510 or 3218.

petra 7y ago
Smallest irsc-v core i know: https://devhub.io/repos/kammoh-picorv32 https://devhub.io/repos/kammoh-picorv32 ~1000 Luts. 1 Lut = 6-24 gates on average. a bit pmore but still pretty close.
- vardump 7y ago
  A LUT can be 10 gates and it can be 100+ gates. You just can't compare FPGA LUTs to gates like that. FPGAs have things like block RAMs and multipliers. Those require a ton of gates, but don't increase required FPGA LUT count by much.
deleted 7y ago
[deleted]
tasty_freeze 7y ago
The Z80 had that many transistors, not gates The CMOS rule of thumb is one gate is 4 transistors (eg a 2-input NAND). But the first Z80 was nmos, and so the equivalent count is harder to state. 3 transistors per 2 input nmos gate is a rough first order guess, but in nmos wide gates still need only a single load resistor, and designers sometimes used dynamic logic to save even more transistors.
- vardump 7y ago
  Ohh... This is embarrassing! I work in embedded/low level and I have always thought that gate == transistor. It's really obvious in retrospect... I stand corrected.
  - marshray 7y ago
    It's not a crazy idea, there are indeed logic types that implement some gate types with a single transistor. For example, https://en.wikipedia.org/wiki/Resistor–transistor_logic https://en.wikipedia.org/wiki/Resistor–transistor_logic These were more commonly used back when transistors were expensive.
kragen 7y ago
Designs like the GreenArrays F18A core show that you can do dramatically more than the 6502 or Z80 did in a similar number of transistors. The J1 and J1A are free descendants. The MOStek and Zilog hackers were wizards but they were working under serious time and, in the Zilog case, compatibility constraints. We know enough to do better now. (https://news.ycombinator.com/item?id=20688443 https://news.ycombinator.com/item?id=20688443 is on the same topic.) (As others commented, those are transistor counts.)