Looking for 1280 x 1024 capable devices under ISC X11

[Martin Cryer]

In article <5506 at umbc3.UMBC.EDU> jimr at umbc3.umbc.edu.UUCP (jim rybacki) writes:
>In article <379 at n4hgf.Mt-Park.GA.US> wht at n4hgf.Mt-Park.GA.US (Warren Tucker) writes:
>>In article <1991Mar21.033435.1888 at buster.stafford.tx.us> rli at buster.stafford.tx.us writes:
>>>Does anyone have a 1280 x 1024 display running under ISC X11.  I
>>
>>I have a fair amount of experience with the Microfield offering,
>>available for ISC and SCO (ESIX too?).  It *ain't* cheap, but
>>it's looks good on a 20" NEC 5d monitor. 1280x1024x256 is a
>>sight to behold.  Anything short of 12 Mb of RAM is going to
>>make you sick though.  Pixmaps of that size are big!
>> 
>>----------------------------------------------------------------------------
>>Warren Tucker, TuckerWare, Mountain Park, GA         wht at n4hgf.Mt-Park.GA.US
>>"The computer can't tell you the emotional story.  It can give you the exact
>>mathematical design, but what's missing is the eyebrows." -- Frank Zappa
>
> I agree that the Microfield looks good on a 5D, BUT it seems to have some
> problems on the 486 motherboards with scsi controllers (both adaptec 1542B
> and WD7000) running ISC2.2, I even tried the new board with the VGA daughter
> card-------- no luck.
>
>----
>echo "Just a guest at umbc"; echo "Disclaimer: These are my thoughts only!"
>                          jimr at umbc3.umbc.edu

You may have trouble if your 386/486 system has more than 16MB of memory...

The problems (this depends upon the Unix you use and the motherboard type)
may be due to the fact that the Adaptec 154X cards are bus master dma
types and as such can only address 16MB of system memory from the 
AT bus. This does not matter if the target buffer is allocated from
the bottom 16MB of memory, but if it isn't, or you are doing direct i/o
to user space above 16MB then the DMA will go to the wrong place!

Also, even if your Adaptec driver copes with this by copying above 16MB 
transfers first (using a below 16MB buffer), then the problem may also
occur when the system DMA's to the Microfield (which does not do bus master
DMA - well the T8's and V8's at any rate). In this case, some motherboards
like the Intel i401 ISA etc, extend the DMA range from 16MB to a much
bigger number by providing an i/o mapped port to write as the top
8 bits of the dma address. This is probably vendor dependent. The
driver you have may not do this.

Another problem is sometimes the Adaptec AT bus transfer speed, try
setting it via the driver (or the board jumpers - but carfull the
driver doesn't override the jumper values) to something less
than 5.7MByte/s. I found 5.0MByte/s to be most reliable on our
mix of motherboards...
(see Adaptec command 0x09 - Set Transfer Speed manual entry....)

The real but expensive solution to the Adaptec DMA problem is to
go to EISA and use the Adaptec 1740 EISA controller in EISA mode.
This really flies.... On a 33Mhz system with EISA SCSI, things really
screem.....

One problem we have with the Microfields, which you may not worry about,
is trying to get them EMI approved as FCC class B devices - they are quite
electrically noisy!

I hope I'm not stating the obvious - enjoy the many colours....

Martin Cryer,
Unisys Europe Africa
Workstations O/S Development
C/O Unisys Corp, D1Z01
322 N 2200 S Salt Lake City
Utah, USA, 84116
801-594-5754

All opinions my own etc etc etc..........