High resolution graphics for the base/unmodified Superboard II / C1P

[Thomas]

during the last few weeks, I was working on a high resolution display project for the Superboard II.
The idea was, to create a module that can be plugged into the board, without the need for any soldering or wiring.
As the prototype started working, I'd like to share some of the features and would like to hear, what you thing about it.

Design goals:
- Single module with standard TTL and IC’s form the 80’s aera to maintain a vintage character(may contain PAL chip, these have been available in the early 80’s)
- Plug and Play, no soldering nor de-soldering nor any modification to the SBII
- Module should not occupy the main extension socket
- Graphics and Text output has to be combined (single monochrome video output)
- Easy to make with today available parts
- Module has to run with standard System ROMs, Text output default at startup
- Module should be able to use the existing Character ROM and display RAM
- No change in memory mapping
- Eventually working on UK101 under 64x16 screen

Feature goals:
- Standard text screen (32x32)
- 8k of High resolution graphic with 256x256 monochrome pixels
- Allow Semi Character set for 128x64 pixel (half and full screen mode)
- Allow Text and Graphic simultaneously on the screen
- Support for 4k Character Eproms (different character sets,..)
- Allow fast access to the 8k HighRes memory
- Support graphic animations comparable to C64 (by character set, not by sprites)
- Provide a kind of “mode register” to select the desired graphic mode

Status:

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- Prototype Module with 12 IC’s tested and working.
- Module is placed with pin header extension in place of the socketed Character ROM and Video RAM IC’s
- Pin header extensions will ensure, that IC sockets are not damaged by standard pin header pins
- Easy to install with no modifications to the main board at all (Character ROM and Video RAM are always socketed)(seems, the UK101 IC sockets have the exact same spacing but 64x16 graphics has to be verified)
- Special video address and addressing technique is used, to provide a graphic mode register (write only)
- Basically a 4 times 2K character RAM is used for High resolution graphic display
- In graphic mode, all 8k character RAM will display the entire 256x256 graphic screen
- SBII character ROM content is readable (can be transferred to the character RAM to display standard text)
- All memory access is done via the 1K video memory address space at full speed
- 4K Eprom or original 2K character ROM can be used. Two character sets can be made selectable
- Semi graphic set can be placed in lower part of the 4K Eprom or loaded into the character RAM
- Semi graphic can be displayed half(top) or full screen
- One 8bit graphic mode register (7 bit used) and a PAL control the R/W modes and general functions
- Two graphic modes used out of 4 available
- Everything fits on a 2 layer board of 70x106mm(2.76x4.17 inches)

see prototype board and mounting option to the Superboard II

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[CommodoreZ]

That is super cool, I look forward to seeing how you pulled that off, and what else you plan to do with it. Nice work!

[bxdanny]

WOW! That is impressive. I wouldn't have thought it possible. Where is the "character RAM" located?

I just might be getting a real Superboard in the reasonably near future. If I do, I think I want one of these. Thomas, I hope you will be selling them as complete kits with all parts included.

[HOWARDHB]

I like it!

[ronin47]

Very neat indeed!

How can I get one

[Thomas]

Just waiting for a revised PCB to arrive and check, if everything "still" works.
Concerning the character RAM used, it's a SRAM cache IC from the late 80's, that was used in all the mainboards with onboard cache.
Here it is a Cypress CY7C185 but also others SRAM up to 32k with the same pin count would work.
These are more easily available than the larger SRAM IC's. And it requires much less space on the prototype.

[Mark]

Nice compact board!
Doesn't the UK101 clock the character generator bits out in reverse order compared to the Superboard? (The schematics show chargen D0...D7 wired in reverse order to the shift register). Wouldn't this make every 8 pixels backwards with your board on the UK101?

[RedskullDC]

Doesn't the UK101 clock the character generator bits out in reverse order compared to the Superboard?

Indeed it does.

Regards,
Leslie

[Thomas]

The character RAM behaves identical to the character ROMs. Because the plug-in board connections from the ROM inserted to the sockets of the main board are 1:1, UK101 character ROM will fork fine on a UK101 or the OSI ROM on a SBII.
Filling the character RAM with images, here you have to take care for the reversed order.
In my test image, I had to take a standard monochrome image (I use Image Spectrumizer from Jari Komppa) and reverse the bit order for the SBII board. Actually the UK101 uses the more common straight forward bit order.

[Scott Larson]

I did something sorta like this with my C1P. I duplicated the video circuit on a separate board and, to simplify, I eliminated the character ROM part and used (I think) 8K of RAM for monochrome bit map graphics. To interface it with the existing character video I tapped the timing from it and I combined the two video outputs with an OR gate.

I began teaching myself how to do bit mapped graphics like drawing lines and circles but the thing began failing. I never figured out what was wrong and I went back to trying to get good grades in my university classes.