Talk:Central Air Data Computer
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[edit] Multichip or not multichip?
The F14 CADC was NOT multichip. This is a cannard put out by the pro-Intel forces to attempt to discredit the CADC as being a microprocessor developed before the 4004. The only thing the CADC did NOT have that the Intel 4004 does is a program counter. The program counter in the CADC architecture was placed on the RAS (Random Access Storage, otherwise known as RAM) and ROM chips to facilitate multi-tasking/processing. A PC could have easily been implemented on the primary processor but this was a pratical design decision only.
Read more about the CADC at the CADC website. --Anonymous
- This is all extremely interesting. The reason I myself haven't looked more closely into whether the CADC was a single- or multi-chip µP is quite simply the website's overall emphasis on the word "chip set", implying more than one chip to make out the CPU. (However, now that I think about it, the 4004 was also an integral part of a chipset---the MCS-4---i.e. RAMs, ROMs, I/O circuits, etc, without which the CPU would be pretty useless.)
- After reading your comment above and browsing Holt's 1971 paper I'm still not 100% sure I completely understand how the CADC system would make up a CPU by combining a single unit of the chipset with a ROM (and optionally a RAS). Therefore, could you please specify what you mean by the "primary processor"? Is it one of the PMU/PDU/SLF units, or one of the other units mentioned?
- As for the "first µP" question, IMO two points of consideration are:
- The CADC is clearly a much more capable and in fact scalable µP system---more of "a real computer"---than the 4004 & Co
- The 4004 may arguably still be reckoned as the first single chip µP if it is the only CPU fitting the "official definition"(?) of a single chip µP
- But another way to look at all this would perhaps be to consider how many chips one actually needs to build a simple computer: the 4004 would also at least need a ROM chip, as the CADC does, to hold its instructions. A RAS/RAM is not essential, of course, since the computer in question might just be doing some simple I/O and calculations fitting within its on-chip registers. Please comment, folks. --Wernher 04:42, 23 November 2005 (UTC)
[edit] Four-Phase Systems AL1
There is also the Four Phase Systems AL8, which preceded the CADC by a couple years, and may well have also been a single-chip 8-bit microprocessor, but it was intended to be utilized as an 8-bit slice of a 24-bit architecture. --Anonymous
- Perhaps you mean the AL1? It almost seems to be a "chip lost to history". :-) Google got me one barely "usable" hit on it, The 8008 and the AL1, which is nothing more than a mailing list excerpt from the "Interesting People Elist". I have written to one of the participants, Nick Tredennick, asking him if he could help us get some more docs on the AL1. --Wernher 06:03, 23 November 2005 (UTC)
