A developer revisits their 1989 Motorola 68000/VME-bus RTOS memory map and benchmarks its 192KB local RAM and design choices against the Raspberry Pi Pico’s 260KB.
Key Takeaways
The 1989 system used 64KB-aligned round-number allocation with intentional unused regions, prioritizing clarity over efficiency because 512KB felt abundant.
50 bps TELEX communication meant the 320KB message buffer would take ~20 hours to fill, making memory the non-bottleneck.
Local RAM (192KB on the 68000 board) is comparable in scale to the Pico’s 260KB; Pico 2 at 520KB exceeds the entire VME global RAM.
RP2040 at 133 MHz vs 68000 at 8 MHz is a 16x clock difference; the Pico is fully 32-bit vs the 68000’s 16-bit bus, suggesting the old comms system could run on a Pico today.
Within a few years of the 1989 design, image and bitmap workloads on a Mac pushed requirements to 48MB, showing how application domain shifts memory demand by orders of magnitude.
