Looking for "Programming CalComp Electromechanical Plotters" book

[Dave Babcock]

Erik wrote:

> thanks for your email. Given this information, I think
> my stuff is not of use for your project...
>
>> We have the schematics for the IBM controller, but don't have one.  We'll
>> need to build our own to connect between the IBM 1620 computer and the
>> plotter.
> I do not know the details on this, but maybe it is easier to
> rip an other plotter using stepper motors and connect the clock
> and direction signals to the 565 directly. There should be quite
> a lot plotter out there suitable for this.

To maintain as much historic authencity as we can to the whole system, we'd 
rather build a clone of the IBM controller.

> What kind of processor does the IBM controller use? In somewhat
> later Calcomp plotters (as mine from 1972) a OPC (online plotter
> controller) was included. The original Calcomp PCB contains a
> 6800 processor which interprets signals from a RS232C interface.
> This PCB generates the signals needed to drive the plotter (i.e.
> step and direction pulses). Since this OPC was optional it might
> be easier to obtain than the IBM part? Maybe they are identical?

I probably overstated it when I called it a controller.  It is discrete 
logic that does a little hand shaking with the IBM 1620 to retrieve plot 
"digits", a simple decode of the digits, then drive the plotter lines with 
the proper timing.  It's a very simple mechanism.  I was avoiding calling it 
an interface because that was how I was referring to the interface circuitry 
within the plotter.  IBM did the design of the "controller" and used the 
"SMS" logic cards that the 1620 is built with.  No CalComp circuitry or 
design was used.

The IBM 1620 was a 1960-vintage computer.  The plotter was available on the 
machine in 1962.

> For the Calcomp OPC I have got schematics and ROM dumps. It has
> the same name as the language it understands "PCI906" and of
> course includes a character generator...

I don't think that this would help us.

>> The information we are looking for is:  1) detailed descriptions of the
>> CalComp HCBS [basic plot] library;  2) the algorithms used by CalComp to
>> implement the plotting functions;  and 3) the vector character font data
>> that CalComp used.
> Sorry, I do not have anything of the mentioned...

I understand.  It's amazing to me how available the document was and yet we 
haven't been able to find one yet.  CalComp was always very tight with their 
source code (a big part of their IP), so I'm not surprised that we can't 
find that.

>> We have no application programs for the IBM 1620 that do plotting 
>> [although
>> we have 200,000 punched cards of programs and data].  We'll be writing 
>> the
>> demo application in addtion to the basic plot library.
> That sounds great - I wish you the very best for this
> project,

We think that it will be very exciting for museum visitors to see.  Most of 
the people will never have experienced a plotter.

Thanks,
DaveB