Subject:
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Re: what is the RCX bios?
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Sat, 13 Sep 2003 02:55:20 GMT
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Viewed:
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3198 times
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In lugnet.robotics.rcx, Jonathan Wilson wrote:
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And what does it actually do?
I mean the small rom inside the RCX...
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It’s a 16K hard-coded driver. It manages the permanent features of the RCX. From
this page:
High level notes
As expected, the ROM contains low-level routines for driving the RCX
It controls the on/off/stall signals sent to the motor drivers
It manages pulse width modulation for the motors
It manages the A/D conversion for the inputs
It manages talking to the serial port
It manages the speaker
It checks messages at a low level
Checks opcodes to make sure they have the right number of bytes
Checks checksum too
Handles opcode 45 specially
ROM calls first address of firmware, firmware never returns
Once firmware is started, it calls ROM to do things
The init_timer function at 3b9a sets up an OCIA handler
OCIA handler called every 1/1000th sec
This is the main asynchronous ROM routine
ROM communicates with firmware using two methods
Two data structures passed to init_timer are updated by ROM
ROM functions communicate data between ROM and firmware
Data at pointers passed to init_serial also updated
The ROM can be completely overridden, if you like
Just don't call init_timer and the H8 is all yours
You will probably still want to use some H8 routines, however
The LCD routines especially
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