29-11-2025, 02:06 PM
If you have a spare 2764 EPROM, go to the repository and download the Universal RAM test ROM ut212
Repository /MbeeTech /Microbee /Software /ROMs /Test /
Replace the boot rom with this and you may get some screen output. It only initializes the bare basics (IE the screen controller).
If you do get a menu up with that, then do a memory test by holding down the G key (for 128k DRAM test) while powering up. You can try any of the options just in case your G key is faulty.
I suspect that you have some faulty DRAM at this point, and running that test will confirm that some of the machine is working at least and you'll be able to see whether the DRAM is working.
Repository /MbeeTech /Microbee /Software /ROMs /Test /
Replace the boot rom with this and you may get some screen output. It only initializes the bare basics (IE the screen controller).
If you do get a menu up with that, then do a memory test by holding down the G key (for 128k DRAM test) while powering up. You can try any of the options just in case your G key is faulty.
I suspect that you have some faulty DRAM at this point, and running that test will confirm that some of the machine is working at least and you'll be able to see whether the DRAM is working.