7. Choose a console

The console is the keyboard you type on and the display TEC-OS answers on. CON moves that connection between a serial terminal, the PICO9918 and the graphics LCD. Its reply is sent through the selected console. BAT: discards it.

Devices and their names

A serial terminal is a terminal program on a PC connected to the board's FTDI serial port. The PICO9918 and graphics LCD use the TEC-1G's matrix keyboard. A serial terminal can be connected alongside both displays but TEC-OS uses one console at a time.

Console name	Keys from	Output to
TTY:	serial terminal	serial terminal
CRT:	matrix keyboard	PICO9918
UC1:	matrix keyboard	graphics LCD
BAT:	serial port	nowhere

TEC-OS uses CP/M's device names: CRT: names the PICO9918 console and UC1: the graphics-LCD console. The command also accepts PICO for CRT and GLCD for UC1. Chapter 17 explains the encoding of those names in memory.

The PICO9918 has 24 rows at widths of 80, 40 or 32 characters. The 128 × 64 graphics LCD has 21 columns and 8 rows. The separate 20 × 4 character LCD is never the console. At cold boot it shows the version and drives. Programs can write to it through the ROM services described in Chapter 12.

A warm boot restarts the command prompt when a program ends and keeps the selected console. Reset runs cold boot and selects the console again from the board's configuration. A responding PICO9918 and the enabled Matrix switch select CRT: at 40 columns before the banner. Otherwise the console starts on TTY:. Chapter 8 explains the startup file that can then load the graphics-LCD console.

The serial terminal

The PC terminal settings are 4800 baud, 8 data bits, no parity and 2 stop bits. The board's clock must be on FAST, 4 MHz. TEC-OS generates the serial timing in software so a different clock setting changes the bit timing. Appendix G lists the physical preparation requirements.

TEC-OS sends output bytes to the serial terminal unchanged. The PC's terminal program interprets control characters and escape sequences. Programs that clear the screen or move the cursor need an ANSI-compatible terminal. TEC-OS cannot read the terminal's dimensions. Its command listings use 80 columns and 24 rows for pagination regardless of the terminal window size.

There is no hardware receive buffer on the board. Input is caught only while TEC-OS polls the serial line. It polls while waiting for a key and briefly during ordinary text output. Keys typed by hand at the prompt are caught. Pasting text or typing ahead of a busy program can lose characters. A host model's queued input does not establish that the physical board can receive a paste.

Moving between displays

CON alone generates a report naming the selected console: CON: TTY:, CON: CRT:, CON: UC1: or CON: BAT:. The report is discarded in BAT:. A name after the command selects that console. CON TTY and CON TTY: are equivalent. An invalid name is printed back with a question mark and leaves the console as it was.

The transcripts in this chapter are host-model captures, not observations of a physical board.

TEC-OS 0.1 for TEC-1G
A: SYSTEM
B: WORK
C: PROJECTS

A>SHELL.SVC

A:SYSTEM>GLCD.SVC

A:SYSTEM>CON XYZ
XYZ?

A:SYSTEM>

On a board using the PICO9918 and matrix keyboard, CON TTY moves the console to the serial terminal. You type on the matrix keyboard and see the command there. The reply and next prompt appear on the serial terminal. This capture shows only the serial output:

CON: TTY:
A:SYSTEM>

The boot text went to the PICO9918. The terminal's first line is the reply. The PICO9918 keeps its old picture but receives no further console output. Input now comes from the serial terminal too. CON CRT typed on the PC restores input from the matrix keyboard and output to the PICO9918.

Selecting a different display clears it and puts the cursor at the top left. A program's claim on the PICO9918 prevents that clear until the claim ends, as Chapter 12 explains. Bare CON CRT and CON PICO retain the selected width and any active claim. After the move back the PICO9918 capture shows only the reply and prompt:

CON: CRT:
A:SYSTEM>

An unavailable display

CRT: requires the PICO9918 console to have started at cold boot. That needs the PICO9918 and the enabled matrix keyboard. Where it did not start, CON CRT selects the serial terminal and reports CON: TTY:.

UC1: requires the graphics LCD, the matrix keyboard and the console driver GLCD.SVC. A driver is a resident service that handles a device. The PICO9918's console code is in ROM so selecting it loads no service file. The graphics-LCD driver is a file on drive A. It loads into RAM and reduces the space left for programs. Chapter 11 explains that memory boundary.

CON UC1 loads GLCD.SVC from drive A if it is not installed. A failed load leaves the console where it was and shows GLCD? on the 20 × 4 LCD. Here both display selections leave a serial-only board on the terminal:

TEC-OS 0.1 for TEC-1G
A: SYSTEM
B: WORK
C: PROJECTS

A>SHELL.SVC

A:SYSTEM>GLCD.SVC

A:SYSTEM>CON
CON: TTY:
A:SYSTEM>CON CRT
CON: TTY:
A:SYSTEM>CON UC1
CON: TTY:
A:SYSTEM>CON
CON: TTY:
A:SYSTEM>

On a board with both displays cold boot selects the PICO9918. The starter card's GLCD.SVC startup line then installs nothing. CON UC1 loads the driver and selects the graphics LCD. This host-model capture used both displays and the matrix keyboard. Its graphics-LCD text capture showed this after the command:

CON: UC1:
A:SYSTEM>CON
CON: UC1:
A:SYSTEM>

Removing the graphics-LCD driver while it is the console selects the PICO9918 if its ROM console started. Otherwise output returns to serial. This separate run on a board with both displays selected UC1, listed the driver and the shell, removed the driver and reported the resulting console:

TEC-OS 0.1 for TEC-1G
A: SYSTEM
B: WORK
C: PROJECTS

A>SHELL.SVC

A:SYSTEM>GLCD.SVC

A:SYSTEM>CON UC1
CON: UC1:
A:SYSTEM>SERVICES
GLCD 3
SHELL 15
A:SYSTEM>UNLOAD

A:SYSTEM>CON
CON: CRT:
A:SYSTEM>

CRT: in the final report names the PICO9918 console after removal. The driver was the newest service, so UNLOAD removed it and left the shell.

A board with the graphics LCD and matrix keyboard can also start without a terminal. Where no PICO9918 console started, the starter card's startup file installs GLCD.SVC before the first prompt. The graphics LCD is the console from then on. Chapter 8 explains the startup conditions.

A silent console and recovery

BAT: is CP/M's batch-device name. In TEC-OS it reads the serial port and discards console output. After CON BAT even the reply disappears. Commands still run when you type them on the serial terminal.

CON TTY typed blind on that terminal brings the visible console back. The matrix keyboard is not the input device in BAT:. In this run DIR ran between the two CON commands but printed nothing on the terminal:

TEC-OS 0.1 for TEC-1G
A: SYSTEM
B: WORK
C: PROJECTS

A>SHELL.SVC

A:SYSTEM>GLCD.SVC

A:SYSTEM>CON BAT
CON: TTY:
A:SYSTEM>

The visible reply belongs to CON TTY, which also restores serial output. If a display goes quiet after a console change, the selected keyboard and display are the first things to check. A move to TTY: needs the serial terminal for both. A move to CRT: or UC1: needs the matrix keyboard. Reset selects the cold-boot console again but loses pending card writes. A console change lets you recover without resetting the machine.

Choosing the PICO9918 width

A width after PICO or CRT sets the PICO9918's width and makes it the console. There must be a space before the number. CON PICO 40 selects 40 columns and CON CRT 32 selects 32. Both text widths, 80 and 40, have 24 rows. The 32-column width also has 24 rows and uses Graphics I mode. The screen clears when the new width takes effect.

Cold boot starts the PICO9918 console at 40 columns when its probe succeeds and the Matrix switch is enabled. A warm boot keeps the selected width. Reset restores 40 before any startup width command runs. This capture selects 32 columns, runs TAS with no name and then lists files across the row:

CON: CRT:
A:SYSTEM>TAS
usage: TAS NAME [OUT.TYP]

A:SYSTEM>DIR /W
SHELL.SVC    GLCD.SVC
STARTUP.CMD  TED.COM
SAMPLE.ASM   TIMES.BAS
TAS.COM      BAZA.COM
BAZA.RTL     BOUNCE.BAS
DEMO.ASM     MON3.SVC
HELLO3.BIN   HELLO3.ASM
14 files, 914K free
A:SYSTEM>

TAS ended in a warm boot, which kept 32 columns. DIR /W fits two names on each row here instead of the six in an 80-column listing, so the starter card's fourteen files take seven rows.

An unsupported width, a width after another device name or a number joined to CRT without a space produces a question mark. The console remains as it was:

TEC-OS 0.1 for TEC-1G
A: SYSTEM
B: WORK
C: PROJECTS

A>SHELL.SVC

A:SYSTEM>GLCD.SVC

A:SYSTEM>CON CRT80
CRT80?

A:SYSTEM>CON TTY 40
40?

A:SYSTEM>CON PICO 50
50?

A:SYSTEM>

A width command typed at the prompt also produces a question mark where cold boot did not start the PICO9918 console. The same line in STARTUP.CMD passes quietly on that board, as Chapter 8 explains.

The matrix keyboard

CRT: and UC1: read the matrix keyboard, not the serial terminal. TTY: and BAT: read the serial terminal, not the matrix keyboard. The basic Shift and Ctrl combinations were introduced with the first commands. Fn gives the same character as the key alone. A modifier pressed alone sends nothing. Two ordinary keys held together send nothing either.

Caps turns Caps Lock on and off. The CAPS lamp lights while it is on. With Caps Lock on letters are capitals with Shift or without it. The { key gives [ and the other keys are unchanged.

The arrow keys send standard ANSI sequences. Programs such as TED read them on the matrix keyboard too. The keyboard lacks ], }, ` and ~. It also has no Delete key. Backspace remains the way to remove the character before the cursor. On a serial terminal that has Delete, its command-line effect differs from backspace:

Key	Effect
Delete, 7Fh	Removes the last character and prints it again, as CP/M 2.2 does on a printing terminal

A matrix key is sent once when pressed. Holding it does not repeat it. A press and release while the program is busy elsewhere can be lost. Chapter 17 explains the scan timing and character encodings.

Text and the cursor on a display

On the PICO9918 or graphics LCD, TEC-OS interprets the text itself. Each printable character is drawn at the cursor and advances it one column. Control characters move the cursor or clear the screen. ANSI sequences provide cursor positioning, screen clearing and reverse video. They also insert or delete characters and lines. Chapter 17 lists the exact terminal subset. A program requiring sequences outside that subset may need a serial terminal with fuller ANSI support.

While a program waits for input on a display, the cursor appears as the reverse image of the character underneath it. The next output byte removes that cursor. No cursor is drawn while its position is past the right edge. A character in the last column leaves the cursor past the edge. Wrapping occurs when another printable character follows. A full-width line followed by carriage return and line feed leaves no extra blank row.