Sub-Etha Software

Tequila and Tortilla and Tandy

December 2, 2021 Sub-Etha Software

Three things that I imagine intersected, if for no other reason than Tandy being located in Texas… But what does the CoCo 3 have to do with this? Stay tuned… (Or go look at Roger Taylor’s project…) …


Commodore VIC-20 PETSCII on the CoCo

December 1, 2021 Sub-Etha Software

In case you ever wondered what the VIC-20 character set would like like on a CoCo 1… VIC-20 PETSCII (Uppercase 0-511) on a CoCo VIC-20 PETSCII (Lowercase 0-511) on a CoCo It would look like that. And if you wanted to know what the VIC-20’s 22×23 …


There is no substitute for real hardware.

November 23, 2021 Sub-Etha Software

I make use of emulation regularly. While I do still have my original Radio Shack Color Computers from the 1980s, it is usually more convenient to just load up an emulator. For short experiments in BASIC, or casual game playing, this works just fine. However, emulation is not perfect and …


String space required. No exceptions.

October 6, 2021 Sub-Etha Software

Revisiting my Color BASIC String Theory series… Here is one to ponder… CLEAR 0 can be used to reserve 0 bytes for string storage. With no string space, we obviously expect something like this to NOT work: A$=”THIS WON’T WORK WITH CLEAR 0″ Indeed, that would give us “?OS ERROR” …


The undocumented syntax of Extended Color BASIC

October 1, 2021 Sub-Etha Software

The other night I was experimenting with Extended Color BASIC and the “GET” and “PUT” commands. I knew that the documentation was incorrect about them, and was trying to figure out how they worked. I also wanted to do this without cheating (i.e., doing a quick web search and finding …


6809 assembly request: make this more better?

September 17, 2021 Sub-Etha Software

Hello, folks who actually know how to program 6809 assembly. Can you make this more better? The idea is to look at each byte on the 32-column VDG screen (from 1024 to 1535) and if the high bit is set ( >128, thus a semigraphics block character), add 16 to …


Color BASIC Attract Screen – part 4

September 15, 2021 Sub-Etha Software

See also: part 1 and part 2. Beyond removing some spaces and a REM statement, here is the smallest I have been able to get my “attract” program: 10 ‘ ATTRACT4.BAS 20 FOR I=0 TO 3:READ L(I),LD(I),CL(I),CD(I):NEXT:Z=143:CLS 0:PRINT @268,”ATTRACT!”; 30 Z=Z+16:IF Z >255 THEN Z=143 40 FOR I=0 TO 3:POKE L(I),Z:L(I)=L(I)+LD(I):FOR …

Sub-Etha Software

Color BASIC Attract Screen – part 3

September 8, 2021 Sub-Etha Software

See also: part 1 and part 2. Previously, I took a target from the attract screen code to talk more on using arrays in BASIC than individual variables. I gave an example of moving ghosts around a screen, and then did modifications to use an array. This let the user …


Color BASIC Attract Screen – part 2

September 1, 2021 Sub-Etha Software

See also: part 1 In part 1, I showed a simple but slow way to recreate a classic CoCo game startup screen with color blocks moving around the screen. I recall many early CoCo games had startup screens similar to this, though fancier. The assembly language games would rotate all …