Apple-410/doc/Apple 401 Plotter.md

The Apple 401 Color Plotter

General concepts

The way the 401 interprets a coordinate at any given time depends on the current viewport and window settings. The "viewport" is a rectangle specified in hardware absolute coordinates and defines the physical area in which coordinates are resolved. The "window" defines the virtual coordinates of the drawing area, which are then mapped to the viewport.

Commands sent to the 401 are terminated by the ASCII "end of text" delimiter, 0x03.

Serial connection

The 8 DIP switches (SW1-SW8) on the back of the plotter are used to configure the serial interface.

SW1 selects the data bits. ON = 7 bits, OFF = 8 bits.

SW2 selects whether parity is used. ON = no parity bit, OFF = use a parity bit. If parity is selected, SW3 determines the type of parity bit. ON = odd parity, OFF = even parity.

SW4 and SW5 select the number of stop bits:

SW4	SW5	Stop bits
OFF	OFF	2 stop bits
ON	OFF	1.5 stop bits
OFF	ON	1 stop bit
ON	ON	invalid

SW6, SW7, and SW8 select the baud rate:

SW6	SW7	SW8	Baud
OFF	OFF	OFF	75 baud
OFF	OFF	ON	150 baud
OFF	ON	OFF	300 baud
OFF	ON	ON	600 baud
ON	OFF	OFF	1200 baud
ON	OFF	ON	2400 baud
ON	ON	OFF	4800 baud
ON	ON	ON	9600 baud

The 401 uses hardware handshaking. It never returns data to the computer over the serial line and sets DSR when its internal buffer is full. Sending even one byte after the DSR line has been set will corrupt the 401's command buffer and trigger an error. Most USB to RS232 cables will attempt to bundle up several bytes before transmission, so unless you're sure that your cable can handle it I recommend flushing the serial connection after every byte and checking the DSR line yourself.

Command Reference

Move Absolute (MA)

MAx,y

Raise the pen and move the plotter head to the position specified by the x,y coordinates.

Params: 2

??Move relative (MR)??

MRx,y

Raise the pen and move the plotter head to a position offset x,y from its current position.

Params: 2

Draw absolute (DA)

DAx,y(,x,y..)

Lower the pen and draw a line from the current position to the position specified by the x,y coordinates. Continues

Params: arb.

==??Draw relative (DR)??==

DRx,y(,x,y)*

lower pen and draw line from current position to an x,y offset. Multiple offsets may be specified in a single command.

Params: arb.

==Circle (CA)==

CAr,x,y

lower pen and draw a circle of radius r centered at x,y.

Params: 3

==Letter size (LS)==

LSs

sets the font size to s

==Letter rotation (LR)==

LRtheta

draw following text rotated by theta in degrees, clockwise

==Print letters (PL)==

PLtext

lower pen and draw specified text at current position

==Pen select (PS)==

PSi

select pen i (where i is in 1-4)

LT - Line type - 1 solid 2 ?? 3 ?? 4 ?? 5 ?? param 6 ??

XT - ? xticks ? -- 5 params YT - ? yticks ? -- 5 params CH - ??? -- no params PM - Point Marking -- 1 param PS - pen select PV - ??? - 1 param WD - window - 4 params AC - arc - 5 params LI - ??? - no params/arb ??? IM - ??? - 2 params PK - ??? - no params/arb RS - ??? - ?0x80 as params? VP - Viewport - 4 params UL - ??? - no params/arb ? 1 param 0-9? SP - ??? - 1 param ?? LF - ??? - 1 param ? 0-9 SL - ??? - 1 param -- Slanted lettering (by %?)