The unofficial

for  Page

(Last update 26.02.2001)
- denotes an addition or change

This Page deals with the following Cornerstone ImageAccel Cards:
(if you have information about others, e-mail me)

SQS - The stupid questions section (Help me to improve this page)

OS/2 2.1, Warp V1.03 - View release notes
NT 4.0 V1.00 - View release notes
Windows 3.1, 95 V1.07 (also includes DOS progs) - View release notes


ID: 80A6

(blue handle on left side removed)

The MC1608C is a secondary video adapter for Microchannel systems. Therefore it plugs into an AVE (auxiliary video extension) MCA slot and uses the systems primary video subsystem for text and low-res graphics. ( It SEEMS to have a built-in base video, which by default is disabled, but can be enabled with a special utility available from Cornerstone. If you know more, e-mail me.) Hardware  accelerator functions are BitBlt (?), line drawing (w. patterns), decompression, image rotation (90, 180 and 270) and scale to gray (16 levels). Video memory is 2 Mbyte.
1024 X 764
1280 X 1024
1600 X 1200
1600 X 1280
Lower resolutions (down to 400 X 300) are provided by the drivers zoom feature (6 levels, up to 4x). Color depth is always 8bpp (256 colors out of 16.7M).
Monitors and Refresh Rates:
The card only supports non-interlaced display modes. The minimum horizontal rate required for multi-frequency displays is 64 kHz!
The card is capable of 1600 X 1280 @ 76 Hz refresh (~120 kHz horizontal rate, ~211 MHz pixel clock), so be EXTREMELY careful or you will fry your monitor.
Explicitly supported displays:
Cornerstone: Color 21/80, Color 21/75, Color 20/72, Color 20/70, Color 21, Color 21/76, Color 17, Color 19, DualPage 120 Color
IBM: IBM 6091-16, 19, 21, IBM 9521/9527  (supported by the C/11 and C/12 only)
Report on Image Accel MC1608C/11 driving an IBM 6091-19 monitor by Helmut P. Einfalt
MC1608C layout
U1...U8 TC528257J-80 (Toshiba) X1 50 MHz TTL oscillator
U9 Cornerstone 1212288-200 (1670F0029) U10 MC1608C/11 12660-003 MYF (BIOS EPROM)
U11 BT467KHF220 RAMDAC U12 ICS1562AM PLL (Synthesizer for pixel clock)
U13 BT471KPJ80 (RAMDAC for base video)  J1 JP1 1..4 jumpers (monitor type selection)
D1 green LED (what for?) CN1 15 pin VGA connector
JP12 JP12 artefact (soldier dots for jumper) JP30 JP30 artefact (soldier dots for jumper, shorted on PCB)

JP1 Jumper settings

JP1 1 2 3 4
Display Type:

Autosync on on on on
Cornerstone Color 19 1 off on off on
IBM 6091-16 and -19i on on off on
IBM 6091-19 on off on on
IBM 6091-23 on off off on
Cornerstone Color 20/70 2 off off on on
Cornerstone Color 21/76 3 off on on on
1 Not supported for ImageAccel 1280 controller
2 ImageAccel 1600/70 and 1600/76 controllers only
3 ImageAccel 1600/76 controller only
Experience (or what I have tested):
MC1608C/11 (JP1-1..4 shorted) in PS/2 Server85 (9585-0XT, 486 DX/2 66MHz), XGA, XGA-2 or SVGA/A base video,
ESCOM 78kHz autosync monitor (DEC clone) connected to MC1608C,
self made terminator plug for base video (75Ohms 1-7, 2-8, 3-9, short 10-11).

All XGA 16bpp modes don't work (Limitation of BT471 RAMDAC or MCA AVE?)
Base video refresh rates can be changed without a problem (XVGARATE works).
Video modes available on XGA base video (obviously) depend on moitor ID delivered by terminator plug.
SVGA/A and XGA-2 don't require the terminator plug at all.

DOS 6.22:  Drivers for 1280 X 1024 @ 64HZ refresh work OK

Black screen with drivers for 1600 X 1200 @ 64Hz refresh
WfW 3.11 Drivers for 1280 X 1024 @ 64HZ refresh work OK

Black screen with drivers for 1600 X 1200 @ 64Hz refresh
OS/2 2.11, 3.0, 4.0 Drivers for 1280 X 1024 @ 64HZ refresh work OK

Drivers for 1600 X 1200 @ 64Hz refresh not yet tested 
Black screen: No whispering "can't sync" sounds from my monitor.
Can exit windows back to the DOS prompt via shortcuts. Same for IA DOS driver test screen.
64Hz @ 1600 X 1200 equals 78.1kHz. This is the slowest refresh for this mode the drivers offer, but 100Hz beyond the limit of my monitor.
Will try a faster monitor soon.
I Used the cable that came with my monitor. Does the MC1608C card read out some sort of monitor ID like the XGA, XGA-2 and SVGA/A cards?
One of the driver READ.MEs mentions a special 15pin VGA - 5 BNC cable that came with the card, but which I don't have. Any clues?

Helmut P. Einfalt uses an Image Accel MC1608C/11 with an IBM 6091-19 monitor under Windows NT4. View his  Report.

Base Video
SVGA/A, XGA and XGA-2 base video cards were tested with their VESA VBE  DOS drivers and VBETEST (from Scitech's Display Doctor).
256 color modes (including the XGA's 1024 X 768 interlaced mode) work via AVE and the ImageAccel, all 64k color modes do not work via the ImageAccel.
Windows drivers for the base video (except 640 X 480 X 16 colors) do not work via AVE and ImageAccel. (Why?)

If you have any question, suggestions or clues, let me know!

SQS - The stupid questions section
If you have a question about the ImageAccel or know the answer to one of the questions above, please e-mail me!

Contact Cornerstone:
Customer Support in the USA 800-562-2552
Customer Support in Europe 49-89-744-15499
Internet: E-Mail
World Wide Web


Links to many MCA related Pages can be found on Peter Wendt's site: LINK

D isclaimer:
All information on these pages is accurate to the best of my knowledge, but there is no guarantee that it is correct.
Therefore I am not responsible for any kind of direct, indirect or consequential damage, loss of profit or anything else.......

All Trademarks are property of their respective owners.
Cornerstone, Cornerstone logo and ImageAccel are trademarks of Cornerstone Imaging, Inc.
IBM and OS/2 are trademarks of IBM corporation.

Copyright (c)2000 Ulrich Trunk