> I have some DRAM boards that I've used with my Poly88.
>These are 64K boards and I thought I'd use them but the disk's
>DMA doesn't seem to write to them. I'm able to read and write
>from the front toggles, just not from the DMA to the RAM.
>
> Does anyone know what the problem is here? Is there some
>timing or pin out issue with DRAMs that would cause this
>to happen in a standard IMSAI 8080? I'd really like to use
>this DRAM because I trust it more than the statics in the
>system, at least until I get things fully functional.
Welcome to the world of S-100, where DRAM boards often didn't
support DMA controllers properly. In some cases, you can rejumper
them so that the DMA vs refresh timing conflict isn't such a problem.
But many of us just went to pure static RAM systems where DMA
was being done.
What disk controller are you using, BTW? In some cases the problem
isn't so much the memory, but it's the disk controller.
> In any case, I think just getting to the A> prompt is
>a major mile stone. I had to completely write a boot loader,
>CBIOS, disk formatter and serial data transfer to get this far.
It certainly is a major milestone. Congratulations!
--
Tim Shoppa Email: shoppa_at_trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
Received on Tue Jun 01 1999 - 15:43:05 BST