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spock181
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Joined: 24/08/2011
Location: Australia
Posts: 1

Posted: 01:50pm 24 Aug 2011

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USR() or CALL

The CALL statement is recommended for interfacing assembly language programs with GW-BASIC. Although the USR function may also be used.

Is there a reason for leaving it out in MMBASIC?

I remember embedding machine code in REM statements in exidy basic.
when you really wanted something time critical.

I can imagine programming an input pin to interupt, with a jump to
a line with a USR() function to process some high speed sampling and then return.
Scanning of an input pin would then occur at maximum processor speed.

I used to do my software uart (RS232) comms like that on an 8085 interupt.
which allowed 9600baud coms on a 2Mhz 8085 (roughly 1 byte per millisecond)

Am I off the mark thinking this is something that could be implemented.
(maybe not assembly programs but binary code execution might be useful)

planet42
Newbie

Joined: 25/08/2011
Location: Australia
Posts: 5

Posted: 01:22am 25 Aug 2011

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To speed things up with the maximite (MM) you could program it in C rather than MMBASIC.

I enquired about this to Geoff Graham (the designer of the MM) to see if I could program it in C, since I've been a C/C# programmer for years now. (Once you know C you never want to use BASIC script. The difference for me is like driving on a smooth highway and then suddenly hitting a road full of potholes :)).

He said that the whole firmware is written in C including MMBASIC, and that you would still have access to the video and keyboard routines, so that it would give me everything I wanted. He also mentioned the firmware source is available for download at the Silicon Chip website or direct from Geoff at http://geoffg.net/maximite.html .

seco61
Senior Member

Joined: 15/06/2011
Location: Australia
Posts: 205

Posted: 04:00am 25 Aug 2011

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Hi Frank.

The facility to execute your own custom code (ie routines written in C - or even assembler using C's ability to call assembler code) is provided by utilising the custom.c and custom.h files.

I have done an implementation using the onboard Output Compare modules to provide a high speed and zero overhead PWM capability.

Regards

Gerard (vk3cg/vk3grs)

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