Just a few tidbits on various items.
Jay Mitchell wrote:
<snip>
>The Solo II timing system sold by Manzanita Micro a number of
years ago used a Motorola 6809. Actually, it used the entire
motherboard from a Tandy Color Computer. If memory serves, the
first generation JACircuits systems also used 6809s.<snip>
The first generations JACircuits timer was totally discrete logic (and, or,
not gates and flip flops and some fancy 4 digit counter/latch/display
driver chips). Reliable, but not very flexible.
Jay also Wrote:
<snip>The bottom line for a computer-based timing system is whether the
time-keeping is done by the host CPU or by external (could be
installed on an I/O bus) hardware. In the latter case, the
timekeeping hardware can easily buffer enough data so that none
would ever be lost between interrupt services. In the case of
Windows computers, I wouldn't really want to rely on the resident
CPU to keep time, as any application that tried to implement that
approach would be at the mercy of Windows' interrupt priorities.<snip>
Prezactly
Paul Foster wrote:
<snip>
Apparently, the battery in the motorhome on the south course ran down on
the second day which gave the timing system inadequate voltage. This
caused the times to be quite erratic and nonlinear. The best example was
Chuck Sample - then a member of the SEB. His 3 runs varied by 8 seconds
although he swore that they should have been within a second of each
other. He protested and lost. But he was right. But he was also wrong
because there was nothing that could really be done about it...<snip>
Actually, Mr. Bonheim plugged the battery charger directly into the timer
(arrrrgggghhhhh!!!).
The post mortem found that the voltage regulator filtering capacitors and
the chip decoupling capacitors just couldn't handle the OUTRAGEOUS noise
levels generated by the charger. The counter/latch/decoder drivers chips
were generating INTERNAL errors resulting in random adds to each of the
digits. T&S threw away the +100 second runs, caught most of the +10 second
runs (except Chuck Sample, Becky Johnson, and a few others), but there were
also +1, +.1, +.01, and +.001 runs that never could be detected.
John
JACircuits Autocross Timing Systems
http://www.mich.com/~jacircts
- Timing the SCCA Solo II Nationals since 1985
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