I just picked up an NEC GB-1 with the CMII / Z80 card.
ET2000 drivers have apparently vanished off the face of the earth.
Found the link to the GB-1 driver on archive.org, but sadly, this file appears to have been omitted from the NEC FTP archive dump.
https://web.archive.org/web/19970606085510/ft … aphics/gb-1.exe
The CM11 module apparently handles translating direct access to the CGA CRTC registers, etc, to the ET2000's chipsets, so that applications that required a real CGA had an actual chance of working - apparently Hercules support is also handled. The CM11 module has 2K of SRAM which I assume the Z80 runs out of - there is Z80 code in the BIOS starting at offset 0x6000. It appears as if the ET2000's registers are memory mapped at 0xC000, so the Z80 can basically reconfigure the ET2000 on the fly as needed.
It looks like there were two DOS utiltiies "CMON" and "CMOFF" one would use to toggle this compatibility.
Probably no way to directly upload code to the Z80 and treat the board as a little mini PGC, but one could always have a bit of fun with a custom ROM.
A lot of the ET2000's features remain unemulated, especially its hardware zoom capabilities, which I'd imagine might have some intriguing demoscene applications.
Interestingly, Michael Abrash appears to have had a hand in designing the ET2000.
The EVA 480, from Tseng Laboratories (205 Pheasant Run,
Newtown, PA 18940, (215) 968-0502) sports a number of ex
tras. Like the […]
Show full quote
The EVA 480, from Tseng Laboratories (205 Pheasant Run,
Newtown, PA 18940, (215) 968-0502) sports a number of ex
tras. Like the other EEGAs, the EVA 480 offers 640 x 480
graphics and complete downward compatibility with the CGA
and HGC, as well as 132 x 44/28/25 and 80 x 60/43/25 text and
Windows, Autocad, and Halo drivers. Because it is built around
Tseng Labs' proprietary ET2000-series chip set (which, in
cidentally, I participated in the design of), the EVA 480 sports
two unique extras: a zoomable hardware window and faster
memory access. The EVA 480 features a built-in hardware window (in addi
tion to the standard EGA split screen), which can start and stop
on any scan line vertically and on any byte boundary horizon
tally. This window can display the contents of any area of EGA
memory, allowing instant popups, for example. The window
area can be zoomed by pixel replication in both directions in
graphics modes and horizontally in text mode, by a factor of
up to 8 times horizontally and 16 times vertically. This could
be very handy for a developer who needs to blow up part or
all of the screen quickly.
The EVA 480 also allows the CPU much greater access to
display memory than does the standard EGA. The standard
EGA allows one CPU access to display memory every four
character clocks while the EVA 480 allows one access every
character clock. During highly display-memory-intensive
operations, the EVA 480 is noticeably quicker than other EGAs.
For example, I ran ATPERF, PC Tech Journal's 286 Performance
and Compatibility Suite ("Out from the Shadow of IBM..."
by Steven Armbrust, Ted Forgeron, and Paul Pierce, PC Tech
Journal, August 1986), on a 10-MHz AT clone in order to deter
mine how many wait states were being inserted by each of the
three EEGAs I've discussed. Both the VEGA Deluxe and the
EGA 2001/PLUS performed at the same speed, inserting 18 wait
states on average—not surprising given that they're built
around the same chip set. The EVA 480 inserted only 9 wait
states, the minimum number of wait states an 8-bit device can
cause during a 16-bit access in an AT. For programs that access
display memory less frequently, the gain will be less, but the
EVA 480 is clearly the faster EGA.
http://ftp.oldskool.org/pub/drivers/IBM/EGA/P … ide_The_EGA.pdf
Hope the drivers for this thing turn up somewhere.
EDIT: There are "Tseng EVA" drivers in the Windows Device Driver Library, Vol 1. That's also an ET2000-based card, but may not have had the 640x480 mode, thus the EVA/480 being branded as it was. Better than nothing!
EDIT EDIT: Found the DOS drivers for the NEC GB-1!
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