Printer Question

General discussions related to the Altair 8800 Clone

Printer Question

Postby AltairClone » March 23rd, 2017, 4:36 pm

As I look at adding support for the Altair Centronics printer interface to the Altair Clone (and possibly the Qume interface as well), I may have to change the way the existing 88-LPC printer emulation currently piggy-backs onto the second serial port in the Altair Clone.

For Altair Clone owners that have used the 88-LPC printer output to drive a serial printer, or to simply capture printer output to a terminal emulator, how important is it that the underlying serial port still be usable at the same time as an 88-2SIO or 88-SIO serial port? In other words, if in the Configuration Monitor you had to choose a single mode of operation for the physical serial port (e.g., 88-2SIO, 88-SIO, 88-LPC, 88-C700 Centronics, etc.), would that be OK?

Any input is appreciated!

Mike
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Re: Printer Question

Postby toml_12953 » March 23rd, 2017, 11:04 pm

AltairClone wrote:As I look at adding support for the Altair Centronics printer interface to the Altair Clone (and possibly the Qume interface as well), I may have to change the way the existing 88-LPC printer emulation currently piggy-backs onto the second serial port in the Altair Clone.

For Altair Clone owners that have used the 88-LPC printer output to drive a serial printer, or to simply capture printer output to a terminal emulator, how important is it that the underlying serial port still be usable at the same time as an 88-2SIO or 88-SIO serial port? In other words, if in the Configuration Monitor you had to choose a single mode of operation for the physical serial port (e.g., 88-2SIO, 88-SIO, 88-LPC, 88-C700 Centronics, etc.), would that be OK?

Any input is appreciated!

Mike


Since I plug a serial printer into the port, I don't need that port to communicate with a terminal emulator at the same time. Those choices would be great for me.

Tom L
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Re: Printer Question

Postby AltairClone » April 7th, 2017, 8:18 am

I finally got a chance to spend some time working on the 88-C700 Centronics printer interface for Altair Clone. Looks like it can piggy-back onto the 2nd serial port in the same manner as the existing 88-LPC emulation after all. This includes the ability to use both the printer device and the underlying serial port device (88-2SIO or 88-SIO) at the same time.

However, there is one exception: The serial and printer devices can't both use interrupts at the same time. This means, for example, when running Timesharing BASIC, you can't use serial port 2 as both a 2SIO user terminal port and the Centronics printer port at the same time. Under normal BASIC however, you could use both ports at the same time since they are not interrupt driven.

The Centronics printer interface is a standard printer type in Altair BASIC since version 4.1. At the "Printer Type?" prompt, type "C" for Centronics or "O" for the original 88-LPC interface (Okidata). Addition of the Centronics printer type allows use of a printer in Timesharing BASIC and in the Altair accounting software which do not support the original 88-LPC printer interface.

I will post in the "Announcements" section when the new firmware release is available.

Mike
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Re: Printer Question

Postby toml_12953 » April 17th, 2017, 8:46 pm

AltairClone wrote:I finally got a chance to spend some time working on the 88-C700 Centronics printer interface for Altair Clone. Looks like it can piggy-back onto the 2nd serial port in the same manner as the existing 88-LPC emulation after all. This includes the ability to use both the printer device and the underlying serial port device (88-2SIO or 88-SIO) at the same time.
Mike


Thanks for the updated firmware! You forgot to change the filename to 1.92, though. Not a biggie but I just thought I'd let you know.

Tom L
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Re: Printer Question

Postby AltairClone » April 17th, 2017, 8:54 pm

Whoops! The .bin file in the .zip file now has the right file name. Thanks!

Mike
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