|Grundy Newbrain 8-bit computer|
One of the games Colin mentioned in his posting was a Basic RPG called "The Valley." This, of course. elicited some complaints from the IF purists in the group that it wasn't really an example of interactive fiction or text adventuring. I think such distinctions are rather arbitrary and was quite happy to hear that Colin had made the file available on the Newbrain emulator site. I am always on the lookout for basic source code!
The Newbrain has a 40X24 screen and the game uses simple "text graphics." Since the MC-10 doesn't have 24 lines, it was useful to be able to use the 64X32 8 color low-res graphics to recreate the text maps. Instead of using various characters to represent the objects on the map (forests, lakes, castles, dark tower, woods, safe path, swamp) I was able to use colours. I also had space left over on the right hand side to put a colour key to explain what each colour represented, since 64-40=24 dots or 12 characters. Luckily there weren't too many items, so 8 colors and black were basically enough to represent everything needed for the maps, with only a little careful doubling up of some colours for slightly different uses on the 3 basic types: terrain, forest/swamp, and castle/tower. The result is a little speedier than the original (I was able to get the game up and running on the Newbrain emulator to help with the porting project), which I think is simply because the MC-10 was developed about 3 years later. As usual, I never know if I have fully debugged, but I will continue to play the game for a while and hope to weed out any that may be left.
In fact, I think I might have spotted some bugs in the original source. I shared this info with Colin on the MC-10 Facebook page. I found an error in line 3820 of the original source that I had downloaded (back in September) that involved a missing colon before a PUT command (how the Newbrain outputs special characters to the screen). Having had my source for some time it's possible Colin or Chris has debugged it in the meantime. I also noticed that line 9000 should probably have had a GOSUB20000 in it instead of GOSUB2000, since the former was a commonly called subroutine, whereas the later was definitely not. However, this GOSUB would possibly never have been triggered in the original because it was in an IF statement looking for a character 230, which I could not find "PUTed" anywhere in the source. My best guess was that a code 254 was what was really needed and adjusted my MC-10 version accordingly to use the right POINT check (to sense the color of the screen locations and return a number from 0-8 for the color found). The command now randomly triggers a message that there is no entry to the buildings on the islands (in the middle of swamps and forests) from the direction one is coming and to seek another route in. So perhaps, the MC-10 version has a feature that even the Kayde original lacked?!
Thanks to John and the other participants in the Retrochallenge, and to Colin and Chris over on the Newbrain site for sharing their retrocomputing enthusiasm!