41CL User Manual
© 2019, Systemyde International Corporation
36
The
YFWR
function automatically executes at 50x Turbo speed, but still requires approx-
imately 4 seconds to complete. The current Turbo mode is restored when the function
completes. The function will either return immediately with an error message, without
executing, or send the
WRITING
message to the display for the entire 4 seconds before
returning.
The figure below shows the formatting required for the address and data in the ALPHA
register for the
YFWR
function. A destination address that is in RAM (destination
P5
is
8 or greater) will return with the
DST=RAM
error message, and a source address that is
in Flash (source
P5
is 7 or less) will return with the
SRC=ROM
message.
ALPHA register
7
6
5
4
3
2
1
source
destination
physical address to physical address
P5 P4 P3
>
P5 P4 P3
Serial Port Functions
The 41CL contains an RS-232 serial port, but unless you have the special PCB connector
this functionality will not be available. However, these serial port functions are present on
all 41CL circuit boards.
The serial port hardware is initialized and the baud rate is set to 1200 whenever the calcu-
lator is turned on. The serial port uses 8N1 format (eight bits of data, no parity, and one
stop bit).
Depending on the baud rate, it may be advisable to run the 41CL in 50x Turbo mode
when performing serial operations to make sure that the CPU has sufficient speed to keep
up with the serial port. The serial port functions do not automatically increase the
processor speed to 50x.
Even using the 50x Turbo mode, at higher baud rates there will be gaps between transmit
characters and the receiver will need gaps between receive characters. This is because
some instructions still run at 1x speed independent of the Turbo mode. Keep this restric-
tion in mind when using the serial block transfer functions. If the source of serial data
generates serial characters without any intervening idle time it will probably be necessary
to use 1200 baud to prevent receive overruns.
The serial port functions only support physical addresses. This means that if you want to
transfer data between a physical module and the serial port the data must be buffered in
RAM memory before the final transfer to or from the physical module.