1968: Fairchild’s Symbol computer - OS & Compiler hard wired
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Author:  BigEd [ Wed Apr 22, 2020 8:22 am ]
Post subject:  1968: Fairchild’s Symbol computer - OS & Compiler hard wired

A remarkable machine, from just before the era of the microprocessor, exploring the possibilities of a multi-chip LSI machine to process variable length records for business computing, by way of a prototype consisting of 100's of cards with 100's of chips on each. All hardwired - no microcode!
Fairchild’s Symbol computer had both the compiler and operating system built with hardware, not software.

fairchild-symbol-prototype.jpg [ 84.6 KiB | Viewed 887 times ]

The memory unit looked after address mapping, paging, and also allocation and garbage collection.

For example, the one-pass (hardware) translator generated a symbol table and reverse Polish code as in conventional software interpretive languages. The translator hardware (compiler) operated at disk transfer speeds and was so fast there was no need to keep and store object code, since it could be quickly regenerated on-the-fly. The hardware-implemented job controller performed conventional operating system functions.

Although we thought about eventually using LSI chips, in the Symbol prototype each of 100-plus two-sided PCBs had about 200 conventional gates and flip-flops. Since an LSI chip would have few pins, all of Symbol's functional units were constrained to have a small number of interfacing signals to meet the LSI chips' ultimate packaging constraints. In retrospect, these LSI considerations were appropriate; they were the compelling factors for the microcomputer's development at Intel three years later in 1969. However, a few key differences distinguish the assumptions underlying the Symbol and the Intel microcomputer. First, the Symbol pin limit was arbitrarily set at 100, whereas the first Intel microprocessor, the 4004, had only 16 pins. Next, the Intel microcomputer had only a 4-bit data word and a dramatically scaled-down instruction set in order to squeeze the entire CPU onto a single chip. Finally, the Fairchild Symbol project was a "super smart" 64-bit computer that would have required a large number of specialized LSI chips.

(posted by whartung on the retrocomputing forum)

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