Fair price and ways to find a teletype

Chuck Guzis cclist at sydex.com
Fri Oct 16 00:19:02 CDT 2015

On 10/15/2015 10:06 PM, Brent Hilpert wrote:

> For working form modern equipment, the bit rates for all of them are
> potentially awkward. When working on the 28s, which were geared for
> 75 bps, I lucked out as I found the USB-serial interface I was using
> could do 75 bps - not entirely surprising as 75 is a factor of 2 down
> in the common 9600,1200,300 bps series. How many USB-serial
> interfaces are capable of this I have no idea. Regardless, the baud
> rates are slow enough that bit-banging from a program is not
> difficult, or an adjustable RC oscillator to a UART should do.

These were more common in the 8-bit area.  Typically, a Z80 machine 
would involve a CTC and DART, so you could set the CTC count/divide for 
any reasonable rate needed.

This is probably the case also for many current MCUs that feature a 
built-in UART/USART or even designs using the Intel 8251--which often 
would be fed by an 8253/54.   I believe the x86 "microcontrollers" such 
ash the 80186EB or NEC V20/V30 would also qualify.

For PC cards using UARTs with built-in divisors, simply changing the 
oscillator crystal would do the trick--IIRC, this was done with early 
MIDI setups.


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