Well, a few things have happened since my Flea86 project introduction from the previous month. This month's latest update will cover the following :
1) Completion of Flea86 case design transfer to CAD.
2) Inclusion of EGA (planar) video support for Flea86.
Completion of Flea86 case design transfer to CAD.
After several false-starts, I have finally managed to obtain a transfer of my original case design to digital form. (click on the initial exploded view image at the beginning of the blog, or alternatively here)
Converting the mechanical design to CAD will allow for easier production of the Flea86 i.e. no more melting plastic with a heat gun! ;-) Should be interesting to see what these things end up costing..
Inclusion of EGA (planar) video support for the Flea86.
Basically, while the tandy graphics are nice, support for this adapter isn't as widespread amongst classic DOS games as EGA - in fact, there were a number of so-called VGA games actually used the EGA screen modes!
Given the above, I decided to at least attempt to write a suitable EGA video driver for the Flea86. Reasoning behind this was if for whatever reason I was unsuccessful, I could always reinstate/improve the tandy graphics for the 16-colour modes.. Attempting EGA on an 8-bit micro turned out to be quite a major effort, probably more than I had bargained for..
Well the results are in - and they're mixed :-/ On the plus side, I managed to get a crude 128K EGA setup to display the following color screen modes on the Flea86 (all 16-color derived from a palette of 64):
Also, my fears of a 'massive slowdown' arising from this implementation turned out to be largely unfounded (will post a video on this shortly):
On the minus side, I had to remove code for the mode 13h (256-colour 'chunky' screen) as well as the 16-color Tandy modes to make room for EGA.. :-( In addition, for technical reasons the higher (350-400 line) resolution modes must be interlaced on the Flea, causing some noticeable display flicker (there are methods that can be applied to minimize this however).
Assuming EGA is the way forward, there's still much to be done in terms of better compatibility, font support etc. etc. I would be interested to hear your thoughts around this.
Ok, that's it for this blog episode - Happy Gaming! :-)