My description of the Comstar 4 product line was in error. Careful reading of the ACM/NCC 1975 description by the company, says the "compiler" was a device with keyboard and 32-character display, which accepted "key per function" features of the PLC language, displayed the entered statement, and accumulated the 4004 "compiled" instructions into a 256-byte EPROM (likely an Intel 2708). Those ROMS operated the Comstar 4 controller which operated the application equipment as programmed. Other Comstar 4 devices, provided diagnostic and testing of the controller and its PLC program. While the PLC language was claimed to be "FORTRAN-like", the document deliberately explains that the compiler product (a machine, not a FORTRAN or other program) is used on-site and avoids the need for some remote computer to process (assemble or compile) some textual program. I can imagine the difficulties Christian had, in trying to determine the function and operation of the Comstar 4 "computer" and "programmer". Especially years ago when knowledge of the 4004/40 was even more obscure. My error goes to my point, that these very early 4-bt microprocessor based products are difficult to interpret from a later view of computing and microprocessor development and use. Regards Herb Johnson On 1/11/2024 2:57 PM, Herbert Johnson wrote:
Apparently that Comstar 4, and certainly early use of the Intel 4004, are examples of industrialm controls. From Christian's documents, the Compstar System 4 was a replacement for ladder-logic or PLC (programmed logic) controllers for industrial control. The PLC program was cross-compiled on some mainframe or minicomputer running a FORTRAN program. That was a very common means of microprocessor programming in the early-mid 1970's. Gary Kildall ... produced FORTRAN assemblers and PL/M compilers for Intel's 8008 and 8080, for development of industrial applications.
-- Herbert R. Johnson, New Jersey USA https://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net