Talk:S-100 bus

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[edit] Comart (UK)

Comart Computers in Britain made a range of S-100 based machines: There was the single-user Z-80 based 'Communicator', and multi-user x86-based machines that ran Concurrent CP/M-86 and possibly Concurrent DOS 386. I wish I could remember more of the details, but the "C-frame" (was this a codename?) had Voltage regulators on each card and ran 18V and 9V down the backplane and the "K-frame" ran 12V and 5V down the backplane and had wire links where the regulators would have been (some cards were common to both series).

[edit] Misc Note

The author of the S-100 page states "A deal on power supplies led to the use of +8 V and +18 V, which had to be "pulled down" on the cards to TTL (+5v) or RS-232 (+/-12 V) levels." I believe the actual reason for these voltages was to allow for on-card voltage regulation. +8v and +18v would have been sufficient to drive the linear regulators of the time (such as the 7805 and 7812). I'm fairly sure I can remember photos of S-100 cards that had these regulators onboard.