Category Archives: RetroChallenge

I’m way behind on reporting on my Retrochallenge project, but I have been working on it. As Dr. Asimov wrote, “Sloane’s Teddy Wins the Race.”  I’ve made progress porting CP/M to the Quay 900.  I’ve improved my disk routines, added … Continue reading →

I put some better error recovery code in floppy disk formatter for the verify pass.   Previously I was getting verify failures on drive 0 when using double density, and the new code reveals that some of them are cleared up … Continue reading →

Mark Wickens asked for photos.  I haven’t taken many, but here are two.

I did a lot of cleanup of my floppy routines, and got the formatter working with double density.  Right now it only runs as a “standalone” program.  Once I have CP/M running on the Quay, I’ll put in conditionals to … Continue reading →

I’ve added volume 2 to the BYTE consolidated advertiser index.  It is provided as an ODF (Open Document Format) spreadsheet.

I’ve been compiling a consolidated advertiser index for the early years of BYTE magazine, thus far from V1N1 (September 1975) through V2N3 (March 1977).  Hey, that’s one more thing to add to my Retrochallenge project! This did turn up some … Continue reading →

I have a Quay 900, which is an obscure Z80-based system from 1979.  It has two MPI (CDC) eight-inch double-sided floppy drives, and uses a Quay MPS-90F single-board computer rather than the then-common S-100 bus, though it has two daughterboards … Continue reading →

As part of my RC2012WW project, I ran an 8080 exerciser and other instruction test programs on a Sol20 to better understand the behavior of the 8080′s flags (which are NOT exactly the same as those of the Z-80), and … Continue reading →

By writing some additional 8080 test programs, running them on both the Sol-20 and my simulator, and comparing the output, I’ve found and fixed several bugs in my simulator.  Now the 8080 Exerciser running on the simulator matches all the … Continue reading →

With a good power supply filter capacitor, the Sol-20 is now running sufficiently reliably that it passed the 8080 Exerciser., generating the expected CRC values. In order to find the bug(s) in the 8080 simulator I wrote last month, I’ve … Continue reading →