[N8VEM: 18418] PropMDA IBM MDA-compatible Graphics Concept

[Andrew Bingham]

All,

I've been brainstorming about ways to get an IBM PC-compatible display
going with readily available parts. Either to use with the SBC-188 (or a
modified version thereof), or the S-100 MS-DOS Support Board + 8088 board.

I think I've come up with a concept that would allow the Propeller to be
used in an IBM MDA-compatible configuration.

This is not the "holy grail" of having a VGA or SVGA adapter but I think it
would be a good starting point as far as running a subset of MS-DOS
programs that manipulate the text buffer directly.

Anyway let me know if it looks like this has any kind of merit.

I have some more ideas in this direction involving a real dual port RAM
PLCC chip + the Propeller that might actually make CGA
all-points-accessible graphics possible as well but I am still doing some
calculations to see if the Propeller can handle it with "all cogs firing".

Andrew B.

[yoda]

Hi Andrew

I think this has been discussed in the propeller forums before and the timing and hub ram size prevents this from working. I think the best approach is to use an fpga to do this. I am looking at several Spartan 6 boards with some of them having 32MB of sdram on them. It is one of the next things om my queue to do.

Dave

[Alan Cox]

You can certainly take a lot of FPGA to VGA or even 1024x768. However much
of it depends on the quality of the base clock on the board.

I've not tried emulating MDA or hercules.

Alan

Post by yoda
Hi Andrew
I think this has been discussed in the propeller forums before and the
timing and hub ram size prevents this from working. I think the best
approach is to use an fpga to do this. I am looking at several Spartan 6
boards with some of them having 32MB of sdram on them. It is one of the
next things om my queue to do.
Dave
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[yoda]

Hi Alan,

I am really going for vga at 1024x768 or 1440x900 or something in that realm. Still trying to decide on 4x3 or 16x9 - the 4x3 is becoming less available it look like so I am leaning towards the latter. The DCM modules on the Spartan 6 look like they will give the flexibility in clocking. Btw did you have any luck with the dram prototype?

Dave

[Alan Cox]

I'm using the DP BRAM on the Papilio Pro FPGA for graphics rather than the
DRAM. Made it much easier to interface and the Z80 doesn't need much video
memory. On the Papilio the board clock is stable enough for 1024 x 768 but
this is not true for all the FPGA boards

Alan

Post by yoda
Hi Alan,
I am really going for vga at 1024x768 or 1440x900 or something in that
realm. Still trying to decide on 4x3 or 16x9 - the 4x3 is becoming less
available it look like so I am leaning towards the latter. The DCM modules
on the Spartan 6 look like they will give the flexibility in clocking. Btw
did you have any luck with the dram prototype?
Dave
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[yoda]

Hi Alan,

I am really going for vga at 1024x768 or 1440x900 or something in that realm. Still trying to decide on 4x3 or 16x9 - the 4x3 is becoming less available it look like so I am leaning towards the latter. The DCM modules on the Spartan 6 look like they will give the flexibility in clocking. Btw did you have any luck with the dram prototype?

Dave

[Andrew Bingham]

-On the timing, for the bus reads and writes, I planned to use an LS
flip-flop or similar to set /WAIT as soon as the /RD or /WR comes in. Then
when the data is read/written, /WAIT can be re-set. The timing of the
Propeller means that the memory reads/writes would be somewhat slower than
a real MDA adapter, but the bus cycle should work out okay.

-The Propeller has 32 x 8 bit of hub RAM. The VGA_Highres_Text driver
already uses up to 8K x 8 bits of this for its largest mode (1024x768 with
an 8x12 font). This would use 4K x 8 bits to replicate the MDA RAM and
80x25 at 720x400 with a version of the IBM Code Page 437 font.

-The VGA_Highres_text driver can display 80x40 columns at 640x480 with 2
cogs already so I don't see an issue on the display output side.

I'd love to see the FPGA VGA happen but I don't have the skills or time to
do it. The Propeller has become a de factor standard for a "modern addon
coprocessor" for N8VEM and the idea was to extend that into a memory-mapped
IBM PC compatible mode.

Andrew B

Post by yoda
Hi Andrew
I think this has been discussed in the propeller forums before and the
timing and hub ram size prevents this from working. I think the best
approach is to use an fpga to do this. I am looking at several Spartan 6
boards with some of them having 32MB of sdram on them. It is one of the
next things om my queue to do.
Dave

[Alan Cox]

Post by Andrew Bingham
I'd love to see the FPGA VGA happen but I don't have the skills or time to
do it. The Propeller has become a de factor standard for a "modern addon
coprocessor" for N8VEM and the idea was to extend that into a memory-mapped
IBM PC compatible mode.

Yep. The FPGA solution seems to work best when you stick the CPU core in
the FPGA as well. For an 8bit micro and supporting logic its basically a
customisable single chip solution where you can stick CPU, RAM and all the
supporting logic on one device.

If your propeller can do MGA you can probably also replicate hercules
display layouts/registers as well which in PC days I always found far more
useful 8)

[Alan Hightower]

_"HOLY GRAIL" OF HAVING A VGA OR SVGA ADAPTER?_

Didn't Sergey already do that with his Trident 9K 8-bit VGA card?

http://www.malinov.com/Home/sergeys-projects/isa-supervga

-Alan

All,
I've been brainstorming about ways to get an IBM PC-compatible display going with readily available parts. Either to use with the SBC-188 (or a modified version thereof), or the S-100 MS-DOS Support Board + 8088 board.
I think I've come up with a concept that would allow the Propeller to be used in an IBM MDA-compatible configuration.
This is not the "holy grail" of having a VGA or SVGA adapter but I think it would be a good starting point as far as running a subset of MS-DOS programs that manipulate the text buffer directly.
Anyway let me know if it looks like this has any kind of merit.
I have some more ideas in this direction involving a real dual port RAM PLCC chip + the Propeller that might actually make CGA all-points-accessible graphics possible as well but I am still doing some calculations to see if the Propeller can handle it with "all cogs firing".
Andrew B.
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[Andrew Bingham]

For ISA, yes. John M. is still working on a solution for S-100.

However in my opinion for the long-term continuation of the N8VEM project
(and as far as I can tell this is the last major community of homebrew
computer builders where people still experiment with new board designs on
very regular basis!) I think we need to have solutions that (a) use "modern
enough" components that the parts will be available for a period of years
and (b) the firmware/software is available so we can update to new parts if
needed.

So Propeller, FPGAs, using SD cards or CF cards for storage instead of
floppies that need vintage chips etc - all of these things are good things
in my opinion.

Not that I don't like playing around with the vintage chip boards (I've got
a tube of 10 uPD7220s here waiting to build that board) but I think it's
good for new builders to have a choice. I really appreciated being able to
build my Zeta + ParPortProp with all modern chip and have the VGA, PS/2,
and SD card storage.

Andrew B

*"holy grail" of having a VGA or SVGA adapter?*
Didn't Sergey already do that with his Trident 9K 8-bit VGA card?
http://www.malinov.com/Home/sergeys-projects/isa-supervga
-Alan
All,
I've been brainstorming about ways to get an IBM PC-compatible display
going with readily available parts. Either to use with the SBC-188 (or a
modified version thereof), or the S-100 MS-DOS Support Board + 8088 board.
I think I've come up with a concept that would allow the Propeller to be
used in an IBM MDA-compatible configuration.
This is not the "holy grail" of having a VGA or SVGA adapter but I think
it would be a good starting point as far as running a subset of MS-DOS
programs that manipulate the text buffer directly.
Anyway let me know if it looks like this has any kind of merit.
I have some more ideas in this direction involving a real dual port RAM
PLCC chip + the Propeller that might actually make CGA
all-points-accessible graphics possible as well but I am still doing some
calculations to see if the Propeller can handle it with "all cogs firing".
Andrew B.
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[Edward Snider]

Pretty much have to keep integrating newer components for long term
continuation.
Supplies of those old chips won't last forever. I think the mix of old
and new is one of the
coolest things about N8VEM anyway.

Ed

Post by Andrew Bingham
For ISA, yes. John M. is still working on a solution for S-100.
However in my opinion for the long-term continuation of the N8VEM project
(and as far as I can tell this is the last major community of homebrew
computer builders where people still experiment with new board designs on
very regular basis!) I think we need to have solutions that (a) use "modern
enough" components that the parts will be available for a period of years
and (b) the firmware/software is available so we can update to new parts if
needed.
So Propeller, FPGAs, using SD cards or CF cards for storage instead of
floppies that need vintage chips etc - all of these things are good things
in my opinion.
Not that I don't like playing around with the vintage chip boards (I've
got a tube of 10 uPD7220s here waiting to build that board) but I think
it's good for new builders to have a choice. I really appreciated being
able to build my Zeta + ParPortProp with all modern chip and have the VGA,
PS/2, and SD card storage.
Andrew B

*"holy grail" of having a VGA or SVGA adapter?*
Didn't Sergey already do that with his Trident 9K 8-bit VGA card?
http://www.malinov.com/Home/sergeys-projects/isa-supervga
-Alan
All,
I've been brainstorming about ways to get an IBM PC-compatible display
going with readily available parts. Either to use with the SBC-188 (or a
modified version thereof), or the S-100 MS-DOS Support Board + 8088 board.
I think I've come up with a concept that would allow the Propeller to be
used in an IBM MDA-compatible configuration.
This is not the "holy grail" of having a VGA or SVGA adapter but I think
it would be a good starting point as far as running a subset of MS-DOS
programs that manipulate the text buffer directly.
Anyway let me know if it looks like this has any kind of merit.
I have some more ideas in this direction involving a real dual port RAM
PLCC chip + the Propeller that might actually make CGA
all-points-accessible graphics possible as well but I am still doing some
calculations to see if the Propeller can handle it with "all cogs firing".
Andrew B.
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[Andrew Bingham]

I agree.

It's too bad Parallax has run into lots of development issues with
"Propeller II".

I think it will open up a lot more options.

Andrew

Post by Edward Snider
Pretty much have to keep integrating newer components for long term
continuation.
Supplies of those old chips won't last forever. I think the mix of old
and new is one of the
coolest things about N8VEM anyway.
Ed

Post by Andrew Bingham
For ISA, yes. John M. is still working on a solution for S-100.
However in my opinion for the long-term continuation of the N8VEM project
(and as far as I can tell this is the last major community of homebrew
computer builders where people still experiment with new board designs on
very regular basis!) I think we need to have solutions that (a) use "modern
enough" components that the parts will be available for a period of years
and (b) the firmware/software is available so we can update to new parts if
needed.
So Propeller, FPGAs, using SD cards or CF cards for storage instead of
floppies that need vintage chips etc - all of these things are good things
in my opinion.
Not that I don't like playing around with the vintage chip boards (I've
got a tube of 10 uPD7220s here waiting to build that board) but I think
it's good for new builders to have a choice. I really appreciated being
able to build my Zeta + ParPortProp with all modern chip and have the VGA,
PS/2, and SD card storage.
Andrew B

*"holy grail" of having a VGA or SVGA adapter?*
Didn't Sergey already do that with his Trident 9K 8-bit VGA card?
http://www.malinov.com/Home/sergeys-projects/isa-supervga
-Alan
All,
I've been brainstorming about ways to get an IBM PC-compatible display
going with readily available parts. Either to use with the SBC-188 (or a
modified version thereof), or the S-100 MS-DOS Support Board + 8088 board.
I think I've come up with a concept that would allow the Propeller to be
used in an IBM MDA-compatible configuration.
This is not the "holy grail" of having a VGA or SVGA adapter but I think
it would be a good starting point as far as running a subset of MS-DOS
programs that manipulate the text buffer directly.
Anyway let me know if it looks like this has any kind of merit.
I have some more ideas in this direction involving a real dual port RAM
PLCC chip + the Propeller that might actually make CGA
all-points-accessible graphics possible as well but I am still doing some
calculations to see if the Propeller can handle it with "all cogs firing".
Andrew B.
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