On Thu, Jun 03, 1999 at 05:21:43PM +0100, Jason Flynn wrote:
> I've been looking into designing a new SCC card for packet
> and making the PCB masks freely available on the 'net.
> I've currently got a USCC and a S5SCC card and I've had
> a good look at how each of them work. I feel that a PCI
> based card is beyond my capabilities so I'm talking ISA!
Echoing presented opinnion that ISA-bus is a thing
from past...
PCI isn't that difficult, all you need is intergrated
chip does does serial communication functions, and also
the PCI-bus things.
Chip makers do supply recommended layout for the PCI
interface lines, and most also *loudly* highlight the
PCI-bus clock delay line.
A negative point might be that it likely needs at least
four layer PCB board.
Dense surface mounted chips are very easy things to solder
at hamshack if pins of the chips are outwards -- PLCC type
are way more difficult, than SOIC. Solder paste is not
necessary, non-acidy flux is.
If you can get couple hours of training from people who do
surface mount work, then you should be all set.
> I came up with a few points I wanted to discuss with people:
>
> 1) What IC would be a good move 85C230 or 16C3x or
> something different again ?
Something different. I would prefer a card which
has more than one port in it, and which runs
full duplex at all of them to at least 2 Mbps.
Perhaps something out of these Brooktree -- err..
Conexant things:
http://www.conexant.com/techinfo/default.asp?action=level_two&L1class_ID=13&L2class_ID=43
> 2) What is a good way of getting the data of the SCC IC?
> ISA DMA? DMA into on card memory mapped RAM ?
PCI bus, and dual-ported RAM at ISA bus with on-chip
DMA machinery working in local chip<->RAM bus.
Possibly USB (or FireWire?) attached semi-intelligent
device might be more of the thing of the future ?
> 3) What are the issues with running both channels
> of a Dual channel IC in DMA mode?
Pain... A *lot* of it, unless you do mean
Bus-master DMA, in which case you get only
medium amounts of pain...
> 4) What are the issues with running full duplex
> and DMA ?
>
> 73 Jason
>
> PS can anyone explain exactly what the bug in the
> z8530 is that everone complains about ?
Which of them ? I mean: Whose 85*30 chip do you mean ?
> PPS can anyone point me to an online manual for
> the 85C230?
www.zilog.com ?
/Matti Aarnio <[EMAIL PROTECTED]> OH2MQK
