Friday, December 30, 2016

Testing of disk tool on Alto system Diablo drive highlights remaining issues


I brought the new board, fpga and related objects over to the Alto, hooked it up to the Diablo on that system and read some cartridges for archival purposes. Unfortunately, I was still seeing sectors with errors.

Something is going wrong, leading to errors which we are not experiencing when the Alto reads the same cartridges. Unless the Alto is ignoring errors and never is affected by any incorrectly read sectors, there is something I can improve in my fpga logic.

We did boot up all the other cartridges we had, which all ran well, but that was with the Alto driving the Diablo. The original disk cartridge we received had been cleared by a utility that overwrote the media with a pseudo-random stream of words. This seemed ideal to use to write an archived disk image which had many Alto games.

This was the first time we tried to use the WriteEntireCartridge transaction, which appeared to work. However, when we tried to boot the cartridge on the Alto, we heard it seek and read from two locations but then stop. Clearly the written data was not done well enough to work properly.

My wishful thinking yesterday, that the surface scratching on the cartridge at my house was the sole reason for checksum errors while reading, is proven wrong. I have to keep working until my tool reads my cartridge entirely correctly (and writes sectors properly). 

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