Stage 4 Software

A project log for Building a 68030 computer in 5 stages

Based on Tiny030 design

PlasmodePlasmode 03/04/2019 at 14:270 Comments

With the addition of 32-bit wide, 16-megabyte DRAM, Tiny030 is capable of running a varieties of application software quickly.  In this project we'll rerun the EhBASIC and memory diagnostic of Stage 3, add a new memory diagnostic for 16-meg DRAM, and do a benchmark of EhBASIC running in DRAM and compare that to EhBASIC running in 8-bit RAM.

The existing ROM monitor runs fine in stage 4 hardware.  It now can access memory located from 0x1000000 to 0x1FFFFFF.

I wrote a memory diagnostic to test 16 meg of DRAM

EhBASIC is relocated to 0x1000000 and allocated 6 meg of RAM.  I measure the time it takes to run the ASCII mandelbrot at 27 seconds.  Compare that to 45 seconds running in 8-bit RAM of stage 3.  The improvement of 32-bit memory over the 8-bit memory is not as great as I would expected.  I believe one reason is because the 8-bit RAM is running at zero wait state while 32-bit memory has 2 wait states for the slower DRAM circuitry.