Sorry for no updates for a while, but my son’s Eagle Scout project is this Saturday so we’ve been working on preparations for it most of the last few weeks.
But on to the fast lane!
For fun, I replaced the 6800 with a 68B00 and cranked up the speed on the CPU board. The variable resister and capacitor combo limited it to 1.791 MHz, but the CPU worked great! The 6850 in the serial board was still working, but I should put in a 68B50 just to be sure. I loaded up Microsoft 6800 BASIC and then an old biorhythm program and definitely noticed the faster CPU.
One place the CPU speed made a big difference was entry of programs. I have a bunch of BASIC program files on my desktop machine and simply upload the ASCII files while in the BASIC interpreter. BASIC tokenizes each line and then inserts it into memory, so if the interpreter is slow, then the next line starts arriving before it’s ready to receive it, resulting in corrupted lines. To overcome this, it’s customary to insert a big delay after each CR/LF to allow the interpreter to process the line, but this really slows things down. Now I can greatly reduce the delay, speeding up the transfer rate.
Oh, and I’ve been stocking up on 2 MHz support chips for another project, but it’s too early to say much.