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15

SWTPC 6800/PR-40 Printer Diagnostic PRNTST-1 

This printer diagnostic has been written to test and/or debug the SWTPC PR-

40 printer when it has been interfaced to the SWTPC 6800 Computer System thru one 

of the MP-L parallel interface boards. It is assumed that before loading this 

program, the rest of the system is functioning normally with no problems. The 

program itself uses 6010 words and is loaded within the 128 word RAM used by the 

MIKBUG operating system on the MP-A Microprocessor/ System Board. A program may 

reside in external RAM memory simultaneously with the diagnostic loaded within 

the 128 word RAM, or the diagnostic may be run with no MP-M memory boards 

installed on the system at all. The diagnostic may be loaded either from tape or 

instruction by instruction using MIKBUG starting from address A014 thru A024 and 

then from address A048 thru A072. The address of the MP-L parallel interface 

board feeding the printer must be set using MIKBUG R to load the hexadecimal 

address of the selected port into memory locations A002 and A003 with the most 

significant byte going into A002 and the least significant byte going into A003. 

The starting address locations of the interface ports are given below: 

 

Port 

Address in Hex 

I/0 #0 

8000 

I/0 

#1 

8004 (reserved for control interface) 

I/0 #2 

8008 

I/0 #3 

800C 

I/0 #4 

8010 

I/0 #5 

8014 

I/0 #6 

8018 

I/0 #7 

801C 

 

Since the program counter is set when the program is initially loaded, the 

diagnostic is initiated as described in the "Go to User's Program" section of the 

Engineering Note 100. Once initiated, the program can be stopped only by 

depressing the "RESET" button. The program may then be re-started after resetting 

the program counter to A04A as described in the "Display contents of MPU 

registers Function" section of Engineering Note 100. 

The diagnostic works by sending out an ASCII carriage return (0D16) 

followed by ASCII characters 2116 thru 3F16 followed by a carriage return (0D16), 
followed by ASCII characters 4016 thru 5E inclusive, repeating itself until 
stopped with the RESET switch. 

Each character is output to the printer by first storing the ASCII 

character's bits 0 thru 6 on output lines 00 thru 06 of the selected MP-L 

Parallel Interface port, then bringing the normally high "Data Ready" line low 

via interface output control line C2 for at least one microsecond then returning 

the line high again. The data must be held stable on the interface output lines 

however until the printer acknowledges data receipt by bringing its normally high 

"Data Accepted" line momentarily low and then high again. This latter low to high 

transition signifies that the printer has accepted the character. The MP-L 

control line C1 fed by this line has been programmed to see the low to high "Data 

Summary of Contents for PR-40

Page 1: ...de X 10 1 2 deep X 8 3 4 high Each unit is shipped with one ribbon and one roll of paper Extra ribbons are available from us while the standard adding machine paper may be purchased in office supply stores Caution When handling the print mechanism itself you must make absolutely sure not to try to rotate the large plastic cylinder that moves the head If this cylinder is rotated so the top is turne...

Page 2: ...nt layout drawing to locate each part and install from the TOP side of the board bending the leads along the BOTTOM side of the board and trimming so that 1 16 to 1 8 of wire remains Solder You should have one 1M ohm resistor left over Install all of the capacitors on the board Be sure to orient the electrolytic capacitors correctly The polarity is indicated on the component layout drawing Solder ...

Page 3: ...d tip Static electricity should be an important consideration in cold dry environments It is less of a problem when it is warm and humid Install MOS integrated circuits ICI and IC2 following the precautions given in the preceding section As each is installed make sure it is down firmly against the board before soldering all of its leads Be very careful to install each in its correct position Do no...

Page 4: ... Solder Now that all of the components have been installed on the board double check to make sure all have been installed correctly in their proper location Check very carefully to make sure that all connections have been soldered It is very easy to miss some connections when soldering which can really cause some hard to find problems later during checkout Also look for solder bridges and cold sol...

Page 5: ...rain relief insert the short end of the line cord and the strain relief into the hole provided on the back of the chassis and release Attaching Connectors to the Print Mechanism The print mechanism is supplied with two connectors installed one for the print head and one for the printer motor The connector for the print head is a fifteen pin AMP connector and will mate to a connector located on the...

Page 6: ... must be installed from the back or numbered side of the connector Take note that J1 on the PR40B board is a 15 pin male connector block while J1 on the PR40A board is a 12 pin male connector block Check to make sure that all electrical connections have been soldered Cut off any extra length of the tabs on C4 if necessary Snap the two PC boards into the chassis The larger PR40A board should be ori...

Page 7: ...ver is secured with 6 32 screws and tinnerman nuts which are also supplied with the kit The four rubber feet should be attached to the outside of the cover about 1 in from each corner Wiring the Printer s Input Data Connector The actual ASCII data fed to the printer is input thru connector J4 on the PR 40A board In order to test and set the calibration controls on the printer it will be necessary ...

Page 8: ...etween 1 and 6 volts depending on the setting of the density control Check each of the seven transistors for this voltage If the voltage goes beyond about 6 volts recheck your circuit board for mistakes DO NOT HOOK UP THE SOLENOIDS UNTIL THE PROBLEM IS CORRECTED After you have verified that all voltages look OK switch the printer off and connect J2 Re load your diagnostic and switch the printer on...

Page 9: ...ard the far left side of the printer where the head reverses direction This non print dead zone gives the motor cylinder and print head time to attain full speed As the head begins its movement from left to right the cam actuated micro switch opens telling the electronic circuitry to start outputting character forming solenoid driving pulses Somewhere before the print head reaches the far right ha...

Page 10: ...h until the character data has been printed and the printer memory is ready for more data The printer will ignore all data sent to it while the data accepted line is low So you will usually want to make sure the data accepted output line is high before sending the printer data to be printed If you are careful not to output data faster than one character per microsecond and allow a minimum one seco...

Page 11: ...g control flip flop IC8A back to normally high state Timer IC5 is a power up clear circuit which empties the FIFO memory and helps prevent random firing of the print solenoids during power up Note When turning the printer off it is best to use the toggle switch on the front of the printer chassis This toggle switch not only interrupts the 120 VAC being delivered to the power transformer on the pri...

Page 12: ...l T1 Green PR 40B J1 pin 7 Yes 17 6 heavy TS 1 B Yes PR 40B J1 pin 8 Yes 18 full T1 Blue PR 40B J1 pin 9 Yes 19 full Tl Green PR 40B J1 pin 10 Yes 20 full T1 Grn Yel PR 40B J1 pin 11 Yes 21 full Tl Blue PR 40B J1 pin 12 Yes 22 full T1 Grn Yel PR 40B J1 pin 13 Yes 23 full T1 Yellow PR 40B J1 pin 14 Yes 24 full T1 Yellow PR 40B J1 pin 15 Yes 25 8 heavy PR 40B 40 Yes PR 40A Ji pin 1 Yes 26 8 aeavy PR...

Page 13: ... 47 mfd tantalum capacitor C4 C6 C10 C12 0 1 mfd disc capacitor C5 0 022 mylar capacitor C13 220 mfd 10 VDC electrolytic capacitor Semiconductors IC1 3351 FIFO memory IC2 5241 ABL character generator ROM IC3 IC7 7407 hex O C buffer IC4 7490 decade counter ICS IC10 555 timer IC6 74121 one shot IC8 7474 dual D flip flop IC9 7420 dual 4 input NAND gate IC11 IC14 IC16 7400 quad NAND gate IC12 7404 hex...

Page 14: ...olytic capacitor C2 470 mfd 25 VDC electrolytic capacitor C3 1 mfd 400 VDC capacitor C4 4000 mfd 50 VDC electrolytic capacitor Semiconductors D1 D6 1N5402 silicon rectifier D7 D8 1N4003 silicon rectifier D9 12 volt 1 watt zener 1N4742 or equiv Q1 SS1122 silicon transistor Q2 T2800B triac Misc S1 DPST toggle switch F1 2 1 2 amp slo blo fuse T1 Power Transformer 120 240 VAC primary 32 VAC 2A 12 5 VA...

Page 15: ...ved for control interface I 0 2 8008 I 0 3 800C I 0 4 8010 I 0 5 8014 I 0 6 8018 I 0 7 801C Since the program counter is set when the program is initially loaded the diagnostic is initiated as described in the Go to User s Program section of the Engineering Note 100 Once initiated the program can be stopped only by depressing the RESET button The program may then be re started after resetting the ...

Page 16: ... the solenoids on the print mechanism which may decrease its operating life If you are using the SWTPC PR 40 printer with the SWTPC 6800 Computer System you may use the OUTCHR subroutine listed from address A014 thru A024 in the PRNTST diagnostic within your own program for outputting characters to the printer The index register must be loaded with the starting address of the MP L Parallel Interfa...

Page 17: ...C A022 E6 LDA B 0 X A023 00 A024 39 RTS A048 A0 MSB Program Counter A049 4A LSB Program Counter A04A FE START LDX PARADR A04B A0 A04C 02 A04D C6 LDA B FF A04E FF A04F E7 STA B 0 X A050 00 A051 C6 LDA B 3F A052 3F A053 E7 STA B 1 X A054 01 A055 86 FSTLIN LDA A 0D A056 0D A057 8D BSR OUTCHR A058 BB A059 86 LDA A 20 A05A 20 A05B 4C LOOP1 INC A A05C 81 CMP A 40 A05D 40 A05E 27 BEQ NXTLIN A05F 04 A060 ...

Page 18: ... A064 86 NXTLIN LDA A 0D A065 0D A066 8D BSR OUTCHR A067 AC A068 86 LDA A 3F A069 3F A06A 4C LOOP2 INC A A A04B 81 CMP A 60 A06C 60 A06D 27 BEQ FSTLIN A06E E6 A06F 8D BSR OUTCHR A070 A3 A071 20 BRA LOOP2 A072 F7 ...

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