[DECtalk] Questions about old DECtalk DTC-01 and DTC-03 units

Don Text_to_Speech at GMX.com
Sat Aug 3 22:43:53 EDT 2019

On 8/3/2019 6:25 PM, Jayson Smith wrote:
> First, it's true that the DTC-01 (the only one of the two I've ever owned or
> used) uses serial communication. However, as far as I know, no modern screen
> reader has drivers for it. However, you should still be able to communicate
> with it using a serial terminal or similar.

I think emacspeak talked to a DTC-01 (but it's been years since I looked,

> Second, I didn't know this until recently, but the settings seem to be stored
> in memory backed up by a lythium? battery. If that battery is dead, it won't
> keep settings when you power it off.

When you next power it on, it will announce "NVR failure" and inform you
that factory default settings are being used.

Prepare a short text file that contains the commands to adjust
each option to your normal preference.  Then, push that stream of
characters into the synthesizer after it has booted, before you use it.

There's no "battery" involved -- so, none to replace.  It's an EEPROM (like
Flash).  But, after a gazillion years, it wears out (all Flash wears out
with use).  The part is still manufactured (e.g., Xicor X2212) but I don't
recall if it is socketed (if not, you'll need unsoldering skills)

> Third, it has a built-in power supply. It uses what in the US would probably be
> called/thought of as a standard desktop computer power cord. At least units in
> the US are set up to accept 120 volts, 60 hz. I have no idea if there are any
> allowances for running it on 240 volts. You would need to know what kind of
> power the specific unit you're considering buying is set up to use, and make
> appropriate adaptations. It must be used on AC power, it does not have a
> battery, nor would a battery have been very useful back in the day, considering
> the size of the unit.

I can't attest to whether or not the power supply is autoranging, or not.
Regardless, before buying anything this old, you'd want some assurances
that the capacitors in it (esp the power supply) haven't "dried out"
(which can cause the magic smoke to leak out!).

It's not terribly exotic (three output:  5/12/-12) but if you wanted to
keep the power supply internal, the form factor could pose a challenge.

There's also a "ribbon cable", of sorts, connecting the two halves of the
clamshell enclosure.  But, the conductors are very large and spaced widely
(not the sort of "ribbon" you'd find connecting to an IDE disk drive).
The connectors on either end of this often develop problems owing to the
mechanical stresses applied as the clamshell is opened/closed.

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