On Monday, September 21, 2020 at 6:45:08 PM UTC-4, DoN. Nichols wrote:
On 2020-08-23, Michael_A_Terrell wrote:
Jim Wilkins wrote:

[ ... ]
An industrial UPS design like the APC 1400 provides fan cooling, a true
sine output, user programmability and twice the load capacity for 10
times the price, $700 vs $70.
Sounds like the Best UPS which I have -- four 12V gel cells
about the size of larger automotive batteries, sine wave output, Sola
type constant-voltage transformer, picks up within a cycle of power
failure, reports power-line frequency, and even graphs the waveform if
you ask.
$700 was cheap, compared to what we had to pay for a rack mounted
UPS at a CATV Headend to keep two computers based on the Motorola
Exorcisor bus, and an external SMS disk storage (Two Shugart 8" drives.
It was designed as a word processing system in the late '70s) system
running. Each of the computers generated six NTSC text outputs to feed
modulators. The 8" disks stored our locally produced program guide. One
active, one backup. The OS was ROM based, so the disks containing the
text files and configuration pages (blocks).
Hmmm ... Exorcisor bus based -- IIRC, the Exorcisor was the
development system for the 8-bit microprocessors -- the MC 6800 and the
MC 6809 in particular.

A ROM based OS sounds like Microware's OS-9 (not the later Mac
OS of the same name.) It was truly capable of being run from ROM,
including applications. That would have been on the MC-6809 (or with a
wider bus, on the MC-68000).

The Shugart 8" disks were hard disks or floppies? I've used
both (actually sharing a single controller card running on MultiBus via
what looked like a SASI (pre-SCSI) interface.) This was in my MC-68000
based v7 unix system. The 8" hard disks used the same control interface
bus as the 8" floppy drives, but had radial data interface. (Kind of
like the smaller ST-506 hard drives.)
It took three of us to lift that monster UPS into the rack.
The Best mentioned above was not rack mount -- it was a
waist-high cabinet on casters. It did take a winch and a 4:1 ratio
pulley system to lift it to the second floor where it now lives.

Enjoy,
DoN.

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The 8" drives were floppy drives. Single sided, hard sectored. No idea what OS it had. It was more like a state machine. One system had the drives, the second didn't. It used a very strange 'Page' system where every file was the same size, and the system configuration pages were read in order, on power up. The one without drives was simple pages. The computer only had 32KB of RAM to store notices like our community bulletin board. The system with drives held our local version of the Electronic Program Guide. It also processed the AP and UPI news feeds from a TTY loop to RS232. During a rbuild, I discovered that I could disrupt the newswires or send fake news if I had wanted to.