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Mac-128k on a $14 MPU, say hAllo to the pico-mac!

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DiTBho:


Pico Micro Mac, see here
VGA hat kit, see here
Firmware for flashing to the Pico, see here

brucehoult:
133 MHz Arm has an order of magnitude more power than an 8 MHz 68000?

I don't think so! He's apparently forgotten that M68k takes 8 clock cycles for a 32 bit register-to-register add/sub/cmp/and/or/eor while the Arm takes 1 clock cycle for this. Shifts and rotates on the M68k take 8+2n cycles where n is the number of bits shifted by -- the Arm takes 1 cycle regardless of the shift amount. Conditional branches take 8 cycles on the M68k even if not taken, 10 if taken. The Pi Pico takes 3 cycles if taken, only 1 if not taken.

Generally speaking, the Pi Pico is going to be more than TWO orders of magnitude faster than the Mac 128k, when running native code.

Of course 68k emulation will eat up some of that. But even if it's a pure interpreter (like in the first PPC Macs) that should eat up only one of those orders of magnitude.

tggzzz:
If it won't run Apple Smalltalk, it isn't a Mac.

SiliconWizard:

--- Quote from: brucehoult on October 27, 2024, 03:56:25 pm ---133 MHz Arm has an order of magnitude more power than an 8 MHz 68000?

I don't think so! He's apparently forgotten that M68k takes 8 clock cycles for a 32 bit register-to-register add/sub/cmp/and/or/eor while the Arm takes 1 clock cycle for this. Shifts and rotates on the M68k take 8+2n cycles where n is the number of bits shifted by -- the Arm takes 1 cycle regardless of the shift amount. Conditional branches take 8 cycles on the M68k even if not taken, 10 if taken. The Pi Pico takes 3 cycles if taken, only 1 if not taken.

Generally speaking, the Pi Pico is going to be more than TWO orders of magnitude faster than the Mac 128k, when running native code.

Of course 68k emulation will eat up some of that. But even if it's a pure interpreter (like in the first PPC Macs) that should eat up only one of those orders of magnitude.

--- End quote ---

Yes it's much more powerful than this, plus there are two cores in the RP2040!
I don't know how the emulated 68k they implemented performs. But the overall speed is probably way higher than an original Mac indeed, at least several times.

Using a RP2350 with QSPI PSRAM could emulate much more powerful 68k Macs too. Using the second core and PIO for generating VGA video in color would be possible as well without much problem.
All that for just a few bucks. Fun stuff.

brucehoult:

--- Quote from: SiliconWizard on October 27, 2024, 08:21:26 pm ---Using a RP2350 with QSPI PSRAM could emulate much more powerful 68k Macs too. Using the second core and PIO for generating VGA video in color would be possible as well without much problem.
All that for just a few bucks. Fun stuff.

--- End quote ---

The Milk-V Duo costs about the same as a Pico -- mine cost $2.99, Arace now has them at $4.99. It doesn't have the PIO, but it has a 1 GHz 64 bit Linux core, a 2nd 700 MHz 64 bit microcontroller core, and 64 MB RAM. It could run qemu-m68k (I have actually used qemu-riscv32-static on it) I expect faster than a 40 MHz 68040 and probably qemu-ppc faster than a PPC601 (first gen up to 100 MHz came with 8 or 16 MB RAM).  The MCU core could very easily bit-bang 24 bit VGA or DVI -- Olimex have got a 48 MHz CH32V003 bit-banging mono VGA in their €1 RVPC kit.

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