6 Jul
1999
6 Jul
'99
2:10 p.m.
"Richard Erlacher" <edick(a)idcomm.com> wrote:
I>There's no reason not to use this type of DMA
on a homebrew system.
Hi
I thought I'd mention, the edge sensitive was a IBM issue,
not specifically Intel.
On a side issue. I have connected two ISA cards to a vary
non-Intel processor ( NC4000 ). I have a older MFM HD controller
and a floppy controller connected. The HD, of course, doesn't
need DMA but the FDC normally ran with DMA. Since I had no
interrupt on my setup, I was able to dedicate the processor
to reading the FDC. The only problem I had was that the processor
was a little to fast for the controller chip and the status
There's no reason not to use cards that have
the same form factor and
same connectors and ISA cards.
I've seen little reason to use DMA at all when processors generally have the
capacity to move data at the bus bandwidth with block transfer instructions.
It's not a religious issue for me to call the bus whatever seems
appropriate. ISA is the "standard" developed around the PC. The signals
are, for the most part, the obvious ones for ANY microprocessor. The
interrupts are the exception, in that they use the ancient and stupid intel
method, namely positive-going and, as you said, edge sensitive interrupts,
which preclude the more sensible approaches to interrupt management. from the internal state machine required me to put a
delay
loop in the code. This processor had no block move instructions
but ran fast enough that it wasn't an issue.
Dwight