[Coco] Serial I/O / Printer port - “printer ready”, etc.

[Allen Huffman]

On Mar 8, 2018, at 10:03 PM, Brendan Donahe <brendan at polylith.com> wrote:
> 
> My TDP-100 is near my DMP-130, so I hooked it up and tried what you
> requested.  &HFF21 doesn't work, and it looks like that would be CD FIRQ
> control (per the Lomont PDF
> <http://www.lomont.org/Software/Misc/CoCo/Lomont_CoCoHardware_2.pdf>).
> However, the least significant bit of &HFF22 was able to detect whether the
> printer was ready and on line or not.  So I think that code should read:
> 
> IF (PEEK(&HFF22) AND 1)=0 THEN printer is ready
> 
> When I put a PRINT PEEK(&HFF22) AND 1 into an infinite loop, I could see
> that turning on and off the printer would affect this bit, as would the use
> of the on-line button.  0 was on and on-line, 1 was off or off-line.

Good catch! That was my typo. My notes say:

PEEK(&HFF22)
Bit 1: 0=ready, 1=not ready