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Radio Shack 26-1145, Hardware Manual

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Summary of Contents for 26-1145

Page 1: ...d Discussion of Digital Signals INSTALLING and Checkout THEORY OF OPERATION TERMinal Program and Listing DECWRITER Application Program Required Equipment TRS 80 Level II with 16K RAM Expansion Interfa...

Page 2: ...12 V 12 V GND RS 232 C SCHEMATIC DIAGRAM...

Page 3: ...driver programs which must be custom designed for the equipment you intend to use In this manual you ll find listings for two such driver programs One allows your TRS 80 to function as a terminal the...

Page 4: ...Interface is designed to mount inside the TRS 80 Expansion Interface For example the external equipment could be a serial line printer a Radio Shack Telephone Interface or a video terminal etc The po...

Page 5: ...racter The stop element is maintained until the start element of the next character is transmitted There is no upper limit to the length of the stop element However there is a lower limit that depends...

Page 6: ...levels and corresponding logic conventions associated with data and control information transmitted between equipment For data interchange the signal is considered in the marking condition when the vo...

Page 7: ...signal should be held in the marking condition during intervals between characters and at all times when no data is being transmitted Received Data Direction from data communication equipment Signals...

Page 8: ...on equipment This signal is used to control the switching of the data communi cation equipment to the communications channel The on condition indicates to data communication equipment that it should c...

Page 9: ...as shown in Figure 2 and remove the Expansion Door 2 Remove two machine screws and washers from the 42 pin con nector 3 Position the RS 232 C Interface as shown Line up the 42 pin connector mounting...

Page 10: ...EXPANSION DOOR MACHINE SCREWS WASHER VIEW OF FLOOR WITH 42 CONTACT CONNECTOR INSTALLED TRS 80 EXPANSION INTERFACE FIGURE 2 RS 232 C INSTALLATION...

Page 11: ...2 Load the cassette tape via the Level 11 BASIC System command using TERM as the label Type a slash symbol and press 13 13 to activate the program which is located at 5000 Hex 3 Correct activation of...

Page 12: ...COMM TERM SWITCH TERM COMM W H 3 WW RS 232 C INTERFACE BOARD DIP SWITCHES S1 S8 IH 1 FIGURE 3 RS 232 C SWITCHES...

Page 13: ...UART is an industry standard general purpose programmable device for interfacing an asynchronous serial data channel to the parallel data structure of a microprocessor The transmitter section of the U...

Page 14: ...5 PIN SERIAL CONNECTOR UART c MODEM STATUS REGISTER LEVEL SHIFTERS HANDSHAKE LATCH TTL TO EIA LEVEL SHIFTERS s EIA TO TTL LEVEL V SHIFTERS _ 5 V IN DC DC CONVERTER 1 VOLTAGE DIVIDER 12 V OUT 12 V OUT...

Page 15: ...ENSE SWITCHES This section is made up of eight single pole single throw switches S1 S8 which you use to select the baud rate bits per word parity odd or even stop bits one one and one half or two and...

Page 16: ...losed Open 7 Bit Word Open Closed 8 Bit Word Open Open PARITY SELECT Odd Parity Even Parity SI Closed Open TABLE 3 OPERATION OF SENSE SWITCHES Logic Conventions The logic internal to the RS 232 C oper...

Page 17: ...IMING DIAGRAM Decode Logic The block labeled DECODE LOGIC in Figure 4 provides eight low going strobes that are used by the RS 232 C These strobes allow the CPU to select any of the registers and latc...

Page 18: ...S REGISTER Execution of this instruction loads the contents of the Modem Status Register into A The information now in A represents information relevant to the status of external equipment connected t...

Page 19: ...4H 150 2 4 kHz Yes 5H 130 4 8 kHz Yes 6H 600 9 6 kHz Yes 7H 1200 19 2 kHz Yes 8H 1800 28 8 kHz No 9H 2000 32 081 kHz 0 253 No AH 2400 38 4 kHz Yes BH 3600 57 6 kHz No CH 4800 76 8 kHz Yes DH 7200 115...

Page 20: ...SENSE SWITCHES UART CONTROL REGISTER AND HANDSHAKE LATCH UART STATUS REGISTER D7 Clear to send Pin 5 DB 25 Even Parity Enable 1 even odd Even Parity Enable 1 even odd Data Received 1 Condition true D6...

Page 21: ...R UPDATES An input operation to Port Address EAH reads the UART Status Register Bits D7 D3 convey information about the current status of the UART Receive Data ready for input Transmitter Holding Regi...

Page 22: ...ART ST ATUS BIT 7 A TEST DATA RECEIVED FOR HIGH JR Z INCHAR TRY AGAIN IF NOT IN A 0EBH LOAD RECEIVED CHARACTER Execution of this sequence will load the character received into register A and the UART...

Page 23: ...installed The TERM inal program will cause the TRS 80 RS 232 C to function as a full duplex terminal which displays ASCII encoded text inputted from the RS 232 C port and which outputs keyboard input...

Page 24: ...the RS 232 C port This is called full duplex or FDX If you short together pins 2 and 3 on the RS 232 C connector the terminal can act in a local mode and keyboard action will directly display on the C...

Page 25: ...ASIC use the Reset push button and enter the desired codes into 50B9 through 50BCH Use TBUG to re enter TERM by a jump to 5000H Note that TERM is located at 5000H through 50BC so that it can be reside...

Page 26: ...3E AA 50CA CD 33 00 50CD F1 50CE E6 7F 50 D0 FE GO 50D2 C3 1C 50 PATCH PUSH AF LD A 5066H AND 38 JR 7 NOFLT LD A 0AAH CALL DSP NOFLT POP AF AND 7FH CP GOH JP OUT OF PATCH GET UART STATUS FROM UCB OV...

Page 27: ...T LD DE SUCB 0006 3 505B C5 PUSH BC OOOc 4 505C Oc 80 LD B SOH 0006 5 505E C34600 JP CIO SEE IF NEW MART INPUT IF NO I LOOK AT KB STRIP PARITY FROM ASCII CONV LOWER TO UPPER CASE IGNORE LF DISPLAY DIS...

Page 28: ...CTRL A IN A CONFIG AND 07 H LD HL BAUDTB LD B O LD C A ADD HL BC LD A iHL LD IX 4 A OUT CONFIG f xuR H RET RESET UART WITH ANY OUT DATA GEI TERM CONFIG SWITCHES STATE SAVE IMAGE MASK OFF BAUD PATE IN...

Page 29: ...information are referred to as device control blocks or DCB s The DCB for the Line Printer begins at memory address 4025H and is organized as shown below MEMORY ADDRESS MEMORY CONTENTS 4025H DCB TYPE...

Page 30: ...DBE9 7F13 E6F8 7F15 F684 7F17 32477F 7Fifl D3EA 7F1C DBE9 7F1E E687 7F28 213F7F 7F23 8668 88180 RESURT EQU 8E8H AN OUT TO THIS L0C RESETS THE UART AN IN RERDS THE RS232 CONTROL BITS 88118 SWITCH EQU...

Page 31: ...E OUTPUT 7F34 D3EB 68538 OUT DTAREG A LOAD HOLDING REG H CHAR 7F36 FE8D 68548 CP 8DH IS IT A CARRIAGE RET 7F38 2864 88556 JR NZ RETRN RETURN IF NOT 7F3R 6E6A 88568 LD C8AH IF SO OUTPUT A LINE FEED ALS...

Page 32: ...o the printer The software first checks to see if Data Set Ready is low and loop tests each time if not When found low it checks the UART s transmitter holding register status bit for a high indicatin...

Page 33: ...with the Level II BASIC LPRINT and LLIST commands Any BASIC programs which utilize this technique must include the BASIC program on page 29 as a part of the coding and this section of code must be exe...

Page 34: ...EXPANSION INTER FACE CARD EDGE CONNECTOR P O RS 232 C 25 PIN SERIAL CONNECTOR 16 18 22 36 32 40 20 30 34 38 20 22 PGND TD RD RTS CTS DSR SGND CD DTR FIGURE 6 RS 232 C CABLE 40 CONDUCTOR TO 25 PIN CON...

Page 35: ...ffirmation of fact including but not limited to statements regarding capacity suitability for use or performance of the equipment shall be or be deemed to be a warranty or representation by Radio Shac...

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