You could always use a quick switch. Since vintage busses are usually AC
terminated with strong pull-ups, they work quick well for bi-directional level
shifting and carry only a few nanoseconds of prop delay. This one from TI runs
off 3.3V, readily available, but a bit expensive:
http://www.ti.com/lit/ds/symlink/sn74cb3t16211.pdf
<http://www.ti.com/lit/ds/symlink/sn74cb3t16211.pdf>
NXP has a similar one that runs off a 5V supply and much cheaper:
http://www.nxp.com/documents/data_sheet/CBTD16211.pdf
<http://www.nxp.com/documents/data_sheet/CBTD16211.pdf>
Both have smaller siblings in the families along with a few variations.
I know nothing about the DEC electrical characteristics, however I've used both
parts above for level shifting ISA, 5V PCI, and MFM (input only) control signals
for FPGA applications.
-Alan
On January 5, 2014 at 2:37 PM "Mark J. Blair" <nf6x at nf6x.net> wrote:
On Jan 5, 2014, at 10:29 , David Riley <fraveydank at gmail.com> wrote:
I'm using a high-speed
comparator for the input buffer, though, since the
DEC spec is 1.5v threshold, far away from any current
manufacture ICs.
What about a 3.3V CMOS gate with 5V tolerance, such as a TI SN74LVC3G04?
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/