IA6805E2
29 August 2007
Microprocessor Unit
As of Production Version 00
Errata
Production Version 00
1. Functional differences between IA6805E2 and Harris and Motorola Versions:
A. Stop mode on IA6805E2 will not halt oscillator. Recovery from stop will be quicker.
B. There is a functional difference between the IA6805E2 and the original device instruction
sets regarding instructions for BSET and BCLR. Analysis: The instructions, BSET and
BCLR (bit set and bit clear), are not supposed to affect the carry flag in the condition code
register but in the IA6805E2 they do. Any situations where the BSET or BCLR commands
are executed between a decision type instruction (branches) based on the carry flag and the
instruction that was to update the carry flag should be considered suspect. Workaround:
The workaround selected by the particular user is code dependent. Software will need to be
revised to address the instruction set issues noted above.
C. There is a functional difference between the IA6805E2 and the original device regarding the
external timer input. Analysis: The original device is edge sensitive on this input (negative
edge). The IA6805E has a synchronizing register on this input. If the stimulus to this input
is a negative pulse less than a clock cycle wide, it is possible that this event will be missed by
the timer circuit. Workaround: The workaround selected by the particular user is situation
dependent. The input pulse either needs to be a minimum of 1 clock cycle wide or the pulse
needs to be centered on the falling edge of the input clock.
2. Observations:
A. Original data sheets for Motorola and Harris are inconsistent when describing timer input mode 2.
Original parts and Innovasic will AND together the timer input with the inverse of the internal clock
(AS).
B. Original Harris part would unpredictably “pre-increment” timer counter when writing to timer
registers. IA6805E2 will not.
C. Original Harris part displays incorrect address on external pins during intermediate cycles (not a
functional problem) of multi-cycle instructions when accessing memory at page boundaries.
IA6805E2 will not.
D. Execution of illegal op-codes on the IA6805E2 will force a system reset. On the original Harris
and Motorola parts, execution of illegal op-codes would produce unpredictable results.
Copyright © 2007
IA211081401-03
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