[vcf-midatlantic] A 4004 Based Microcomputer the Comstar System 4

[William Dudley]

256 byte EPROM would likely have been a 1702, no?

Bill Dudley
This email is free of malware because I run Linux.


On Thu, Jan 11, 2024 at 5:47 PM Herbert Johnson via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> 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
>