Terry_Kennedy
Thank you very much for your very enjoyable post, too!
It makes me reappear long ago memories vividly.
The Superbrain
An all-in-one computer, ready to be placed onto the desktop! No more separate units, like CPU, drives, terminal.
But if I remember correctly, when I saw it back then, I disliked that its display's dot matrix was very coarse. I mean, you could clearly see every char being composed of seven or so lines, like the IBM logo split into horizontal lines.
And as the whole stuff was way more expensive than today, and way less standardized, there was much custom manufacturing, as
ralphbsz' also very interesting report confirms.
If I understand correctly, you basically designed a custom system for Fisher, designed to be well-adapted for publishing, which they sold as a complete hw/sw package to publishing customers.
But it was no mainstream system like Cromemco, NorthStar, Altos, etc, whose components were advertised in BYTE etc and of which I do not remember having seen more than 8 chips per byte.
The reliability issues you mentioned regarding the fickle DRAM timing and its potential to cause instability and mangle data are a good reason to use SRAM, especially when high-value work involved.
To be honest, I had been curious which chips you used (I guess 6167 or the like). I guess then you will have put 64k (or at most 128 if tightly packed) onto a memory board and have 8 or 4 memory cards in that 22-slot monster rack, maybe filling only every second slot to maintain a good ventilation?
Whatever, a bit sad is that there seem to be no photos etc. Such would illustratively document what design quality is possible when there is no need to sell individual components as cheap as possible.
Thus, despite the fact that I believe you, I can only say that I never saw parity protected memory systems on 8 bit. I can say I know of anecdotal source that apparently some existed in some high-end small-scale manufactured systems, but cannot prove it.
Anyway, your story and the ECC topic points to the crucial questions:
How cheap is sensible?
How much quality and security can we afford, do we want to afford to sacrifice?
Highly actual, in the view of Meltdown and Spectre, as these things reportedly originated in the attempt to cut reliabilty of safety in order to lower manufacturing costs.
In the end, the extra cost per chip would have been minor, considering the whole system cost.
But, isn't it a crazy idea if, for example, a nuclear plant blows up causing trillions of damages, only because safety logic was ommitted in a processor which would have increased the whole system cost by, say, $10 at max?