build log 6 - ROM, basically

A project log for hexahedron

An open-source minimalist 68030 based VMEbus computer

Jason WesterveltJason Westervelt 12/24/2021 at 07:500 Comments

my apology for lack of updates... got a million things in flight IRL at the moment and very little cache to deal with them all...

i needed to get ROM and SRAM attached to hexahedron, so i built a wirewrap adapter for the PLCC44 ROM that I have.  around that point, i realized that my ROM programmer is only good for 8-bit ROMs.  No problem, I can build an adapter...

T W O   H O U R S   L A T E R

I threw a test pattern at it... 0xAA55... and it worked... GREAT!

...or not.  When I decided to fill the thing with `0x00000000`, you know, for that sweet `ORI.B #0, D0` free-running code, i realized that it was returning 0x80408040.  obviously two of my data lines were not properly connected.  after throwing another half pound of solder on the back of the adapter, all was well...

unfortunately, now i have to handle a few non-maskable interrupts in real life, so i won't be able to test the free-running from the ROM until tomorrow.  i will, however, share the schematic in a few minutes showing my idea for jumperless IO base address configuration.