Dick Smith MKII System 80 Microcomputer User Manual

Dick Smith MKII System 80 Microcomputer

Product Information

The MKII System 80 microcomputer is a new generation of the MKI System 80 and is designed for professional applications. It features a Z80 CPU, 16K user memory, 13K ROM, a keyboard, a cassette interface, and a video interface. The ROM includes a TRS80 Level I compatible Extended BASIC Interpreter, as well as new keyboard and display routines. The system also includes a dumb terminal routine and a HOST routine. It has a cassette interface with a transfer rate of 500 baud, allowing for loading of TRS80 compatible cassette tapes. The system has expansion capability through an expansion edge, enabling connection to an expander for additional features such as minifloppy disk drives, printer, RS-232-C interface, and more. The expander can increase the total user memory size to 48K and provide a S-100 bus option for specific applications.

Product Usage Instructions

1. Ensure the power switches of the computer and its peripherals are in the ‘OFF’ position.
2. Connect the cables between the main unit, expander, and peripherals.
3. Turn on power for the peripherals first, then the computer.
4. If the system is not connected to an expander, a message ‘READY?’ will be displayed on the top left corner of the screen.
5. Press the NEWLINE key, then another READY message should appear on the bottom of the display.
6. The computer is now in BASIC. To enable the new keyboard and display routines, type in SYSTEM followed by pressing the NEWLINE key.
7. The computer will prompt with *?.
8. Enter /12288 followed by pressing the NEWLINE key.
9. The computer will immediately go back to READY, and a blinking cursor will be displayed.
10. If a minifloppy disk is connected to the system, repeat steps 6, 7, and 8 immediately after entering Disk Basic.

Keyboard Layout

The System 80 MKII Keyboard consists of 71 keys, including special function keys:

• BREAK – break a running program and return to the Active command level.
• NEWLINE – enter a line of command or data into the computer.
• BACKSPACE – cancel the character previously entered.
• TAB – move the cursor eight positions to the right. The computer echoes a [ sign which is an exponent sign used by the system.
• [[◂]] – move the cursor to the beginning of the next line.
• SHIFT + DELETE – delete line.
• CLEAR – clear screen.
• ERASE – same as the BACKSPACE key.
• ENTER – same as the NEWLINE key.
• F1, F2, F3, F4 – programmable function keys.

INTRODUCTION

• The MKII System 80 microcomputer is a new generation of the MKI System 80 and is designed for professional applications. Its design philosophy is very similar to that of many other general-purpose computer systems. The main unit is composed of a Z80 CPU, 16K user memory, 13K ROM, a keyboard, a cassette interface and a video interface.
• Out of the 13K ROM, 12K is the Extended BASIC Interpreter which is TRS80 Levell I compatible, and 1 K contains new keyboard and display routines that make the operation more handy. A dumb terminal routine and a HOST routine are built in.
• The video interface can display upper and lower-case characters. The display format is 64 characters/line and 16 lines/screen. The display can automatically scroll.
• The cassette interface operates at a transfer rate of 500 baud, and TRS80-compatible cassette tapes can be loaded through the interface.
• The system also has great expansion capability. Through the expansion edge, it can be connected to an expander, from which, minifloppy disk drives, printers, RS-232-C interfaces, etc, can be linked to the system. The expander can increase the total user memory size to 48K and provide an S-1 00 bus option for users’ specific applications.

POWER ON PREPARATION

Following is the procedure to set up the system.

1. Ensure the power switches of the computer and its peripherals are in the ‘OFF’ position.
2. Connect up the cables between the main unit, expander and the peripherals.
3. Turn on power for the peripherals first, then the computer.
4. If your system is not connected to an expander, a message ‘READY?’ will be displayed on the top left corner of the screen.
5. Hit the NEWLINE key, then another READY message should appear on the bottom of the display.
6. The computer is now in BASIC. To enable your new keyboard and display routines, type in SYSTEM @EWLINEl
7. The computer prompts with *?.
8. Enter /12288lNEWLINEI (See Remark)
9. The computer will immediately goes back to READY. You will see a blinking cursor.
10. If a minifloppy disk is hooked to the system, do step 6, 7, 8 immediately after entering Disk Basic.
    REMARK: See Section 4.4 for other entry points.

KEYBOARD

The System 80 MKII Keyboard consists of 71 keys

Special Function Keys

MORE ABOUT THE KEYBOARD

The key functions mentioned in the previous section are the original functions without
enabling the additional ROM routines, exactly the same as that of the MKI machine. Now,
MKII adds three extra useful functions. They are the automatic key REPEAT,
PRINTSCREEN and SHIFT-LOCK.

REPEAT KEY
After pressing a key longer than one second, the computer automatically repeats
entering that character until the key is released.

PRINT SCREEN
Hitting SHIFT- [I] – P, the computer will transfer the information displayed on the
screen to the printer. If no printer is hooked, the computer will skip the printing process
instead of locking up itself in waiting.

SHIFT LOCK
The new keyboard routine has two input mode: Basic mode and Typewriter mode.
Initially, the Basic mode is set. It looks like an ordinary terminal keyboard. Every keystroke gives upper case character, but with the SHIFT key depressed, it gives lower case characters.
To switch the keyboard to the Typewriter mode, hit the SHIFT Okeys. Then, the cursor will change from a large block to a small one which indicates that every alphebatic character input will be of lower case. In this mode, when the SHIFT key is depressed, it gives upper case characters. However, operation of the numeric keys are the same for both modes. Hitting a numeric key with the SHIFT key depressed will always give a symbol; without SHIFT, it is a number.
Switching back to Basic mode from the Typewriter mode, simply hit the SHIFT- III-a keys again. The cursor will change back to a large block.

Disable cursor flashing

A flashing cursor can attract the operator’s attention, however, somebody may feel it frustrating.
To disable the flashing cursor, hit SHIFT-BREAK. To enable it, hit SHIFT-BREAK
AGAIN. If you don’t want a flashing cursor at the start, you can enter 12299 instead of 12288 described in step 8 of section 2.
NOTE: Sometimes, you may want to neglect the new keyboard routine because of software compatibility. In such a case, 12294 should be entered in step 8 of section 2.

LOADING AND SAVING CASSETTE PROGRAM

The computer has a cassette interface that can be connected to any audio cassette recorder. The user therefore can use cassette tapes as a cheapest medium for his program storage. A cassette connector is provided, and the connection is shown in the diagram.

PROGRAM LOADING

Following is the procedure for program loading. In using the INPUT# command, the procedure is similar.

• a) Insert a cassette into the recorder.
• b) Unplug the remote (blue) plug.
• c) Wind or Rewind the tape until at the program’s beginning.
• d) Plug in the remote plug.
• e) Enter CLOAD (refer to BASIC manual if you want to specific filename).
• f) The computer turns on the cassette and starts searching the program. Once it is found, two asterisks will appear at the top right corner of the screen, the one at the right will be flashing from time to time indicating that the program is loading.
• g) After loading finishes, the computer turns the cassette off and returns to Active Command Level.
  NOTE: Volume of the recorder should be set to medium level. If loading is unsuccessful, try to make a small adjustment on the volume.
  Loading machine code tape should use the SYSTEM command instead of CLOAD; users are advised to refer to chapter I of the BASIC manual.

PROGRAM SAVING

Following is the procedure for program saving. In using the PRINT# command, the procedure is similar.

• a) Unplug the remote (blue) plug.
• b) Erase about 5 seconds of the tape.
• c) Plug in the remote plug.
• d) Enter CSAVE “F”, where “F” represents the filename. The user needs not to input the cassette number since the system can only be connected to one cassette.
• e) The computer turns on the cassette and records the program onto the tape. No asterisk will appear on the screen.
• f) The computer goes back to Active Command Level after the saving has completed. Then, the cassette will be turned off.

PROGRAM CHECKING
The program on a tape can be compared with that stored in the memory of the computer by entering a CLOAD? command. The operating procedure is exactly the same as  that of the loading. The only difference is to type in CLOAD? instead of CLOAD. A READY message will appear when a successful comparison has completed. Otherwise, the word BAD will be displayed.

SYSTEM RESET

The system must, in some cases be reset. When, for example, the machine is running in a dead loop. The Reset Switch is located at the right side of the bc.ck panel . Pressing the reset switch causes the computer to return to the ‘READY’ mode without changing the memory contents.

The system runs in a dead loop in the following cases:

1. loading a program from the cassette which contains an invalid file, or when the volume of the recorder is poorly adjusted.
2. executing LPRINT or LLIST instructions without hooking up a printer to the system or having not turned on the printer.
3. executing an inappropriate POKE instruction.
   The CPU is reset everytime when the power is on. Turning the system off and on immediately is not a good practice; because it may cause improper initialization of the CPU.
   Therefore, the user should wait for about 15 seconds before turning on the system again.

UTILITY-DUMB TERMINAL, HOST

Every computer user should be very familiar with what a terminal is. It is a piece of equipment for sending data to or retrieving data from the mainframe at a remote location. Nowadays, nearly all terminals use the same interface standard, that is, RS232C. The System 80 expander also has an RS232C option. Inside the additional 1 K ROM, a ‘dumb terminal’ routine is provided. Entering the routine, the machine will switch itself into a dumb terminal. Every keystroke by the user ‘-:Viii be sent out in the form of ASCII code through the RS232C interface. Simultaneously, every characters received through the interface will be displayed. The keyboard functions are the same as those discussed in Section 3 and 4 except the repeat key is cancelled. User can still use the PR INTSCREEN to produce a hardcopy of the information displayed. Another utility designed to work with Terminal routine is the Host routine. In the Host mode, resources of the Host computer, such as disk, printer, etc., will be controlled by commands through the terminal only.

DUMB TERMINAL

The procedure to enter the routine is:

• a) Enter SYSTEM, the computer will response with’*?’.
• b) Enter I 13037
• c) The computer will ask ‘DUPLEX? (F/H): ‘ ; F stands for Full duplex and H for Half duplex.
• d) Enter ‘F’ or ‘H’ to select the desired mode.
• e) You are now in the terminal mode.
• f) To exit, hit the RESET switch.
• g) If a printer is connected, characters displayed will also be output to the printer.

HOST

The HOST routine is a communication routine utilising the RS232C interface. It allows a Host computer to hook to a remote terminal. The terminal operator can input data to or retrieve information from the computer. What the terminal is doing will also be displayed on the Host screen.

Working procedure of the Host user:

1. Enter the Host mode, type in SYSTEM, the computer will display’*?’, then enter/12996
2. A message “HOST ENABLE” will send from the Host to the terminal.
3. The Host computer will lock its keyboard up and wait for input from the terminal.
4. If the Host user wants to terminate the Host mode, he should hit the [I) and BREAK Key simultaneously.
5. A message “HOST/TERMINAL DISCONNECT” will display on both the Host and the Terminal.

Interconnection
The RS232C signal of the Host and Terminal should be connected in the following way:

NOTE: The Host entry point 12996 has no line feed on carriage return. If you are using a terminal with no auto line feed. Please enter the Host by 12999.

APPENDIX A TECHNICAL SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

• POWER CONSUMPTION: – 25W (MAX.)
• CASSETTE INPUT LEVEL: – 1 V peak to peak
• COMPUTER OUTPUT RECORDING LEVEL: – 0.3 V peak to peak
• REMOTE SWITCHING CAPACITY: – 0.5 A max at 6 V DC
• VIDEO OUTPUT: – 2V peak to peak (Negative sync pulse)

CONNECTORS PIN ASSIGNMENTS

DIN JACK PIN CONNECTIONS FOR ADDITIONAL CASSETTE

1. REMOTE
2. SIGNAL GROUND
3. REMOTE
4. INPUT
5. OUTPUT

DIN JACK PIN CONNECTIONS FOR VIDEO INTERFACE

• 1 – +5 v
• 4 – VIDEO OUTPUT
• 5 – GROUND

DIN JACK VIEWED FROM REAR SIDE OF THE SYSTEM
EXPANSION PIN EDGE VIEWED FROM REAR SIDE

PIN CONNECTIONS FOR EXPANSION INTERFACE

PIN

| ****

SIGNAL

| ****

DESCRIPTION

| ****

PIN

| ****

SIGNAL

| ****

DESCRIPTION

---|---|---|---|---|---
1| GND| GROUND| ****

26

| ****

A10

|
2| GND| GROUND| 27| A13|
3| A7|  | 28| A11|
4| A6|  | 29| A12|
5| A5|  | 30| PHI| 1.79 MHz clock
6| A4|  | 31| PINT| INTERRUPT
7| A1|  | 32| NC| NO CONNECTION
8| A3|  | 33| NC| NO CONNECTION
9| A2|  | 34| PHLDA| PROCESSOR HOLD ACKNOWLEDGE
10| AO|  | 35| PHANTOM| PHANTOM
11| D5|  | 36| HALT| HALT ACKNOWLEDGE
12| D2|  | 37| PWAIT| PROCESSOR WAIT
13| NC|  | 38| IORQ| INPUT/OUTPUT REQUEST
14| D1|  | 39| PHOLD| PROCESSOR HOLD
15| DO|  | 40| WR| PROCESSOR WRITE
16| D3|  | 41| RD| PROCESSOR READ
17| D7|  | 42| CCDBS/ST ADBS| CONTROL AND STATUS BUS DISABLE
18

19

| D6

vcc

| ****

+5V SUPPLY

| 43

44

| MREQ

DODBS/ADDBS

| MEMORY REQUEST

DATA AND ADDRESS BUS DISABLE

20| D4|  | 45| M1| FIRST STATE OF INSTRUCTION CYCLE
21| A15|  | 46| RESET| CPU RESET
22| A8|  | 47| RFSH| DYNAMIC MEMORY REFRESH
23| A14|  | 48| NM I| NON-MASKAB LE INTERRUPT
24| A9|  | 49| GND|
25| NC| NO CONNECTION| 50| GND|

APPENDIX B MEMORY MAP AND 1/0 MAP

MEMORY MAP

l/0 PORT ASSIGNMENT

• CASSETTE INTERFACE- FF, FE
• PRINTER INTERFACE- FD

APPENDIX C ASCII TABLE

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