Grzyb wrote on 2024-02-22, 14:03:
Jo22 wrote on 2024-02-22, 13:38:
Interestingly, the manual for CL-GD542x series doesn't mention any (D)CGA/Hercules register compatibility.
I find this to surprising, considering that this is an ISA compatible VGA chip.
The Acumos AVGA/Cirrus Logic 54xx series was designed from scratch in 1991 - too late to bother including the legacy stuff.
The ET4000AX is barely older and has it (chip '89 released, actual cards widely produced in early 1990).
The ET4000AX did even feature DCGA (AT&T/Olivetti mode).
That mode was also being used in XTs on a chip and in Japan.
Even more so, the ET4000AX driver diskette has a driver for IBM 8514/A support.
To be honest, I think that Cirrus didn't really target DOS platform, but rather specific applications.
The manual I've found lists support for MS Windows, AutoCAD, OS/2 2.x and so on.
As if these were specific applications, rather than DOS as a platform.
I don't mean to judge here, each to his own.
It's just that it seems the chip or thatAcumos/Cirrus didn't focus on industry standards, but rather popular applications.
As far as compatibility goes, the manual is all about "EGA 640x350 16c and VGA 640x480 16c and beyond".
Edit: It's this one here .
Page 2-13, "Hardware/Software Compatibility"
Edit: The ET4000 perhaps wasn't entirely built from scratch, but it wasn't directly based on previous design, either.
Both the ET2000 and ET3000 had advanced windowing, zooming and panning features.
None of them survived into the ET4000AX.
Btw, why was the obscure Cirrus chip being chosen for the Book8088 in first place?
Why not a Trident 9000? Or good old 8900 (DOSemu emulates one) ?
It's no complaint (well it is, but just a little one). But I'd be interested to know. Was it price or availability, maybe?
I mean, I could understand if, err, there was a surplus of those Cirrus chips in China. 😉
Edit:
The Acumos AVGA/Cirrus Logic 54xx series was designed from scratch in 1991 - too late to bother including the legacy stuff.
I mean, that's technically right. In fact, VGA was in my books since 1988 or so.
But here in my place there were still Turbo XTs in use in early 90s, simultaneously. Aka the dinosaurs.
Which still ran existing Hercules or MDA compatible software at the time (no software upgrade).
And especially for users of those systems, an upgrade to VGA was a warm welcome.
I mean, by 1990 about everyone with a basic knowledge about PC hardware knew about how important VGA as the "new kid in town" would be.
Well, almost all of then.
Except for those enternal backwards fellow citizens of mine at the time who still had thought that a C64 was so much better than an KIM-1..🙄
They didn't realize anything, of course. Still don't. *sigh*
But back to PC.. Even XT owners did think about the VGA upgrade in the early 90s.
Most then-current DOS software simply assumed it (gratefully).
But in practice, how to do this upgrade, if not through excellent backwards compatibility of your shiny new VGA card?
By 1990, an XT with VGA upgrade was an old PC, but no longer a relic.
On the other hand, existing XT-specific software couldn't be sacrificed in favor of having VGA.
And last but not least, what about those DOS games from morning lands that used Hercules in the 90s? 🙂
There are at least 5 popular Hercules games I've seen, besides the usual VGA titles (which some of are great conversion from PC-98, btw).
There's Korean Dungeon Boy, of course, but also a Monopoly type of game. Have to check how it was called. 😅
Edit: Sorry, I forgot to explain. I did mention XTs here because Book8088 is an XT level hardware platform, too.
So that's why these thoughts came to be in my mind. Sorry for the long post, too. 😅
Edit: I forgot a second thing to mention.
Hercules wasn't an XT exclusive thing by any means.
Developers and offices had gotten *new" Hercules card/monitor, still. For 286/386 based systems.
My father had used a Hercules setup in his PC/AT in 1989/1990.
It simply was a common graphics standard at the time, not necessarily a relic as such.
So I don't think that the decision of not including Hercules support in a VGA chip was a sign of progress, whatsoever.
Hercules was aged, yes, but so was DOS.
Certain fields still had a need for MDA or Hercules.
I mean, the Hercules compatibility mode wasn't just about graphics, but also about IBM MDA support. IBM text-mode support.
On a text-based system like DOS, that makes Hercules register compatibility even more important than VGA.
Because it's an 100% compatible super set of IBM MDA.