The HP-71 and the Ubiquitous Binary File

[J-F Garnier]

(08-15-2020 06:52 PM)Christoph Giesselink Wrote:  

(08-15-2020 04:19 PM)J-F Garnier Wrote:  The HHP and CMT 32K and 64K EPROM modules are using one logical chip (and a single EPROM actually) so the checksums of each 16KB block were no more really needed, and the CMT tools are using a single checksum byte that is simply the last byte of the EPROM.
I found this checksum scheme much better and simpler.

I don't agree with this. IMHO a single 1 byte checksum over a size of 32KB or more makes no sense in my eyes any more. The risk of multiple errors resulting into a correct checksum grows with the size of the checksum area.

I don't agree with your point either :-) 32kB or even 64KB doesn't make a big difference vs 16KB.
The risk of multiple errors resulting into a correct checksum grows with the number of errors, not the checksum area.
A single byte fault will always be detected and the chance of a double random byte fault to still produce the same sum is 1/256.
It also depends on the failure modes: is the main failure mode a single bit error, a full nibble or byte random change, or a large memory area read as zero or FF?

J-F