On Thursday 17 December 2009, [email protected] wrote: >re: CP/M > >No S-100 bus systems mentioned yet?
Sorry, my omission. The first gizmo I ever built, in 1979, was a Quest Super Elf, which has an expansion connector on its board that allowed an s-100 buss backplane to be plugged into it. It had an RCA 1802 cpu, running at a whopping 1.79mhz, but its full machine cycle was 8 clocks. I wrote, in hex by looking it up in the excellent rca programmers manual, entering it into memory from a hex monitor using a 6 digit led display, a program to take a finished tv commercial tape from the production guys, run the tape deck to search for and mark the first frame of video to see air, tell it how long the commercial was in time with 6 presets from 10s to 2m. It would then back the machine up about 12 seconds, roll it fwd and enable the insert edit mode of the machine and lay a new, frame accurate 10 second academy countdown leader that I wrote the routine for and built the hardware to display it in 103 line high characters, disappearing at T-2.0 seconds, laying a trigger tone for the automatic station break machine at T-5.0 secs in the process, and continue to the end, laying another trigger tone on the 2nd audio channel 5 seconds from the last frame to air. In use for a decade+ at KRCR in Redding CA where I was the ACE at the time. I still have a paper copy of the program on one of the higher bookshelves above me. And given enough time & access to graveyard electronics, I could rebuild the cg and interface boards yet. Simple stuff really, ran in about 1200 bytes of the $400 4k static ram board I bought and built for it. Lots of it was lookup tables, at least 40% of the ram used, was used as lookup. Self modifying code snippets scattered all thru it to conserve ram, designed in without ever having a clue as to how much ram it would take to do the job and I was surprised that it came in at the size it did. And dead stable despite the self-modifying as it effectively rebooted itself at the end of every job. It was a job humans were doing, and screwing up the timing of, and it saved a generation of dubbing loss, a very valuable feature in the days of u-matic tape machines being used in tv broadcasting. Biggest problem was in getting the production people to leave me 15 seconds of good black in front of the commercial itself I love to remember, but really, this is off topic... -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> The sooner you fall behind, the more time you have to catch up.
