View Single Post
Old 4th May 2021, 4:41 pm   #4
Michael Haardt
Join Date: May 2021
Location: Titz, Germany.
Posts: 41
Default Re: New SC/MP II system

I got ESS-002 and ESS-004 as MP3 files from the web, but unfortunately I lost the URL. The physical records are probably unobtainium.

I converted the MP3 files to WAV, hoping for the best, and then used the rtty software to convert FSK back to a byte stream (rtty contains a UART decoder), saved all continuous byte streams and ended up with lots of tiny files from noise and a few large chunks from the actual tracks. I stripped off the framing with a small program and the CRCs were fine. There is a bug in Elbug: The check sum is the addition of all data bytes in the record. Due to a bug in Elbug the carry flag is reset at the beginning of a record instead of before each data byte addition, so it is folded back into the sum. I am still organizing things, which is why I did not release any software so far, but after 40 years I guess there is no need to hurry.

I got kitbug sorted out, as a bunch of images is on the net for various baud rates and CPU speeds, but NIBL is still a mess: I have two NIBLE binaries that are slightly different in just a few bytes, one NIBL binary without serial functions and one with them, plus source I can assemble to the latter. Guessing, there were NIBL bugfixes that probably explain the byte differences. Funnily NIBL uses the same GECO and PUTC function as kitbug, but with the MSB bug in GECO fixed.

The NDR Klein Computer (NKC) offers DMA, but has no bus arbitration and expects the CPU to coordinate DMA accesses: No SMP. It largest strength is the modularity: Pull the Z80 or 68008 CPU card, plug in the SC/MP card and you have a new computer. Anybody who wants one can download Gerbers and have it manufactured:

The biggest problem is probably the language: All German, as it was featured in a German TV series in the eighties.

It is news to me that the SC/MP would ignore CONT in case of an interrupt, but I did not pay such close attention to the possibility of halting it really.

Michael Haardt is offline