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Text File | 1993-06-07 | 43.0 KB | 1,656 lines

; ; ; SWTIME01.Z80 07/07/87 ; ; ; This program is designed to interface to the Dallas ; Semiconductor SmartWatch/TimeKeeper family of Real Time Clock ; (RTC) parts. ; ; The SmartWatch includes its own crystal time base and ; lithium battery. The SmartWatch maintains time information, ; including hundredths of a seconds, seconds, minutes, hours, day ; of week, day of month, month and year. The date at the end of ; the month is automatically adjusted for months with fewer than 31 ; days, including correction for leap year. Hours of the day can ; be tracked in either 12- or 24-hour format. ; ; These time keeping devices are offered in several socket- ; style hybrid versions of the DS1215--"TimeKeeper". These ; clock/calendar devices, fit into 28-pin 0.6-inch-wide DIP (Dual ; In-line Package) memory sockets. The following summarizes the ; different devices: ; ; ; DS1216: Intended for a 2K or 8K byte low power CMOS static RAM. ; When system power is lost, the RAM draws power from the DS1216's ; battery. ; ; DS1216C: Intended for a 8K or 32K byte low power CMOS static RAM. ; When system power is lost, the RAM draws power from the DS1216's ; battery. ; ; DS1216E: Intended for a 8K or larger EPROM. ; ; The SmartWatch requires no interfacing, it merely plugs in ; between a existing 28 pin socket and a existing 24 or 28 pin RAM ; or EPROM. ; ; ; ACCURACY: ; ; The data sheet for the SmartWatch rates the part to be ; "Accurate to within one minute per month @ 25'C". However there ; are two things that the data sheet doesn't tell you, that will ; cause the SmartWatch to lose time (appear to run slowly): ; ; The first problem is related only to the nonvolatile RAM ; type device. On these devices the voltage powering the RAM must ; not go below three (3) volts. ; ; The other problem, that effects all types of SmartWatchs, is ; that the voltage at the Write* input, (pin-27 on all devices ; except the DS1216E, which has Write* on pin-8), must not go above ; the Vcc voltage (pin-28). This usually only happens if you are ; driving the SmartWatch with a CMOS logic level, and the Write* ; voltage 'over-shoots' Vcc. ; ; There are two disadvantage of inserting the SmartWatch ; between the existing socket and the existing devices: ; ; The main disadvantage is that it raises the hight of the ; RAM, or EPROM, by about one-half inch. So if your existing ; socket has low head room, the SmartWatch may not be the clock for ; you. ; ; The other disadvantage is that there is a slight increase ; in memory access time, in most situations this is of little ; concern. ; ; ; ; Be careful when trying to plug the SmartWatch-Socket into an ; other socket. Some types of sockets, such as machine-contact-pin ; sockets, may not readily accept the flat pins of the ; SmartWatch. ; ; Contact Dallas Semiconductor directly for data sheets, and ; to find out who distributes the SmartWatch in your area. ; ; Dallas Semiconductor Corporation ; 4350 Beltwood Parkway South ; Dallas, TX 75244 ; ; (214) 450-0400 ; FAX# 214-450-0470 ; TELEX# 6502441669 ; ; ; [Information pertaining to Dallas Semiconductor components ; are reprinted by permission.] ; ; {By the way I have no connection to Dallas Semiconductor, ; other than being a user of their parts.} ; ; ; ; NOTE: ; This program is "Copyright (C) 1986-1987 by Robert Paddock". ; All rights reserved. Users are hereby granted a limited license ; to copy this program for personal use only. The program may be ; distributed unmodified to all interested parties. No fee or ; other consideration shall be accepted by any party or parties. ; In accordance with the Copyright Law of 1978, form TX has been ; sent to the U.S. Government Copyright Office. ; ; ; If you have changes that you would like to see in a ; forthcoming general release, please forward them for ; consideration. ; ; Send/call any suggestions or requests for help to: ; ; ; Z-NODE #38 ; (814) 437-5647 ; 24 hours/ 7 days ; 300/1200/2400 Baud, 8/N/1 ; Robert Paddock, KA8BMT, SYSOP ; ; ; May time be on your side................ ; ; MAIN EQU 1 ; Main version number VERS EQU 0 ; Revision number ; VMONTH EQU 07 ; Date of revision VDAY EQU 07 VYEAR EQU 87 ; ; ; ------------------------------------------------------------- ; NO EQU 0 YES EQU NOT NO ; ; SB180 EQU NO ; 'YES', if using a SB180 SB180FX EQU YES ; 'YES', if using a SB180FX ; ; If using a SB180, or SB180FX, then we must deal with the ; Memory Management Unit, of the 64180. Also we can set the ; BIOS clock from the SmartWatch. ; ; IF SB180 AND SB180FX ERROR: Select only SB180, or SB180FX, not both. ENDIF ; SB180 AND SB180FX ; ; USEEI EQU NO ; 'NO' if your system doesn't want the ; ; interrupts turned on. ; INTEI EQU USEEI OR SB180 OR SB180FX ; ; Since some systems need the interrupts on (like the SB180) ; and some need them off, it is best that we put the interrupt ; enable bit back the way the system wants it. ; ; ; EDATE EQU NO ; NO=Month/Date/Year, YES=Date/Month/Year. WEKDAY EQU YES ; Print 'SUN,MON,.....SAT'. ; ; BASE EQU 0000H ; BASE of CP/M ; BIOS EQU BASE BDOS EQU BASE+5 FCB EQU BASE+5CH TBUFF EQU BASE+80H TPA EQU BASE+100H ; LF EQU 0AH ; Line Feed CR EQU 0DH ; Carriage Return ; ; ; ; From SYSLIB 3.6: EXTRN COUT,CONDIN,PSTR,PRINT,PA2HC,CATH,CRLF ; ; To assemble and link, using SLR's assembler/linker: ; ; SLR180 SWTIME ; LNK180 SWTIME/A:100,SYSLIB/S,SWTIME/N/E ; ; ; SmartWatch and TimeKeeper, ; are trademarks of Dallas Semiconductor. ; ; 'SB180' and 'SB180FX' are trademark's of Micromint Inc. ; ; Z80 and Z180 are trademark's of Zilog. ; ; HD64180 is a trademark of Hitachi. ; ; ------------------------------------------------------------- ; .Z80 ; For M80 (SLR180 ignores it) .SALL ; Don't list expanded macros. ; ; SWAP MACRO ; Exchange nibbles. RLCA RLCA RLCA RLCA ENDM ; ; ------------------------------------------------------------- ; IF SB180 OR SB180FX ; ; If SB180 or SB180FX then we must relocate the program so ; it is not within the first 4K of RAM (40000H-40FFFH), so that ; when we access the SmartWatch at address 00000H, we don't get ; lost. ; ; .XLIST ; Don't list these ; MACLIB PORTS.LIB ; .LIB file(s) ; ; .XLIST ; Don't list .LIB's ; MACLIB PORTS.LIB ; 64180 (and SB180) ports. ; ; [Supplied with the SB180(FX)] ; ; MACLIB OP-CODES ; 64180 OP-CODE MACROS (For M80) ; ; [Can be found in the BYE5 ; ; insert for the SB180(FX)] ; ; .HD64 ; (For ZAS) ; ; (SLR180 doesn't need either) ; .LIST ; Listing back on ; ; ; ------------------------------------------------------------- ; ; RUNADR EQU 3000H ; Could be any RAM address below the CCP, ; ; and above 40FFFH; on the SB180(FX). ; ; LD HL,FSTADR ; Relocate the program LD DE,RUNADR ; so that it is not LD BC,LSTADR-FSTADR LDIR ; in the first 4K of RAM. ; ENDIF ; SB180 OR SB180FX ; ; JP START ; Ok, lets get some useful work done now. ; ; ------------------------------------------------------------- ; FSTADR EQU $ ; Start of section that may need relocated. ; ; IF SB180 OR SB180FX ; .PHASE RUNADR ; Generate code at the current location ; ; for later transfer and execution at ; ; RUNADR. ENDIF ; SB180 OR SB180FX ; ; ; Since you most likely want to see how to deal with the ; SmartWatch, the code for doing just that, is listed here in the ; beginning: ; ; ; $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ ; ; Because EPROMs don't have write (WE*) inputs and your data ; bus may not be bidirectional at the EPROM data output pins, ; address lines A0 and A2 serve as the DS1216E's data input and ; WE* pins, respectively. ; ; DS1216 EQU NO ; Nonvolatile RAM type SmartWatch DSEPRM EQU YES ; EPROM type SmartWatch [DS1216E] ; IF DS1216 AND DSEPRM ERROR: Select only DS1216 or DSEPRM not both. ENDIF ; DS1216 AND DSEPRM ; ; NOTE: The above equates only affect the way that the device ; is written, they both use the same read routine. ; ; WATCH EQU 0000H ; Base address of the SmartWatch. ; ; ; *** NOTE: The WATCH equate above MUST match the hardware address ; of the SmartWatch, other-wise this program will not be ; able to access the SmartWatch. *** ; ; Most systems have a boot-strap-EPROM at address zero, so ; this seems like the most logically place to put the SmartWatch. ; This boot-strap-EPROM can usually be switched in and out of ; memory, so make sure you account for this switching. ; ; If you are using a 64180 be aware of what the 64180 Memory ; Management Unit is doing. ; ; SWWRB0 EQU WATCH ; Address to write a zero bit. (DS1216E) SWWRB1 EQU WATCH+1 ; Address to write a one bit. (DS1216E) SWRDD0 EQU WATCH+4 ; Address to read a bit from. (DS1216[E]) ; ; ; OSCILLATOR AND RESET BITS: ; ; Bits 4 and 5 of the day register are used to control the ; reset and oscillator function. Bit 4 controls the reset (pin ; 1). When the reset bit is set to a logical 1, the reset input ; pin is ignored. When the reset bit is set to logical 0, a low ; input on the reset pin will cause the SmartWatch to abort data ; transfer without changing data in the watch register. Bit 5 ; controls the oscillator. This bit is shipped from Dallas ; Semiconductor set to logical 1, which turns the oscillator off. ; When set to logical 0, the oscillator turns on and the watch ; becomes operational. ; ; RSTPIN EQU 00010000B ; We want to ignore the reset pin. ; OSCOFF EQU 00100000B ; Bit 5 is high if not set. OSCON EQU NOT OSCOFF AND 0FFH ; Bit 5 is low if set. ; OSCRST EQU OSCOFF OR RSTPIN ; OSC off, and ignore the ; ; reset pin. ; ; ; ------------------------------------------------------------- ; ; ACCESS: DI ; We must turn the interrupts off! ; ; ; If the interrupt service routine (assuming there is one), ; would happen to read or write to the MEMORY location of the ; SmartWatch, while we are trying to read or write the CLOCK ; section of the SmartWatch it is possible that the SmartWatch ; and/or the interrupt routine could get confused, since neither ; know about the other. ; ; Cycles to other locations outside of the SmartWatch's ; memory block, (ie. the SmartWatch's Chip-Enable [pin 20] not ; active) can be interleaved with SmartWatch cycles without ; interrupting the pattern recognition sequence or data transfer ; sequence. ; ; Since some systems need the interrupts on (like the SB180) ; and some need them off, it is best that we put the interrupt ; enable bit back the way we found it, before we turned it off. ; ; Unfortunately some other type of interrupt, such as a Non- ; Maskable-Interrupt (NMI), could still come along and mess ; everything up, if it accesses a SmartWatch address. Oh well, at ; least we tried.... ; ; Probability says that nothing bad will happen. On the ; other hand Murphy's law says that the worst possible thing ; will happen at the worst possible moment. ; ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180 OR SB180FX ; ; We have to turn the DRAM hardware refresh off, to ; prevent spurious EPROM chip selects. ; IF SB180 ; XOR A ; Do a software refresh LD B,A ; so that we will have a whole LD L,A ; 4 mS to deal with the SmartWatch, LD H, HIGH $ ; before we have to worry about ; ; the DRAM refresh again. ; REFIT: LD C,(HL) ; We do this by reading 256 INC HL ; bytes of the 256k DRAM. DJNZ REFIT ; ; ELSE ; SB180FX ; XOR A ; Do a software refresh LD B,A ; so that we will have a whole LD L,A ; 4 mS to deal with the SmartWatch, LD H, HIGH $ ; before we have to worry about LD D,A ; the DRAM refresh again. LD E,A ; REFIT: LD C,(HL) ; We do this by reading 512 LD A,(DE) ; bytes of the 512k DRAM. INC DE INC HL DJNZ REFIT ; ENDIF ; SB180 ; ; ------------------------------------------------------------- ; IN0 A,(RCR) ; We have to turn the DRAM LD (SVRCR),A ; hardware refresh off, to AND 7FH ; prevent spurious EPROM chip ; ; selects. OUT0 (RCR),A ; Turn the hardware refresh off, now ; ; that the software refresh is done. ; ; ------------------------------------------------------------- ; IF SB180FX LD HL,(BIOS+1) ; Get the BIOS's page address, then LD L,3FH ; point to the BIOS LATCH stuff. LD (BIOSLATCH),HL ; XOR A ; Read the FX latch. CALL LATCHVAL LD (LTCHIMG),BC ; Save the latch image. RES 3,B ; Select EPROM [RAM/ROM*]. CALL SETLATCH ; Set the FX latch. ENDIF ; SB180FX ; ; ------------------------------------------------------------- ; IN0 A,(CBAR) ; Save the current CBAR value, LD (SVCBAR),A ; then map the first for 4K AND 0F0H ; of ROM into Common Area 0. OR 01H OUT0 (CBAR),A ; ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; ; Communication with the SmartWatch is established by ; pattern recognition of a serial bit stream of 64 bits which ; must be matched by executing 64 consecutive write cycles ; containing the proper data on the Data In pin (D) [D=D0 (pin 11 ; of the 28 pin socket) for the DS1216, D=A0 (pin 10 of the 28 ; pin socket) for the DS1216E]. All accesses which occur prior to ; recognition of the 64 bit pattern are directed to memory. ; ; ; A read cycle to any memory location of the SmartWatch ; starts the pattern recognition sequence by moving a pointer to ; the first bit of the 64 bit comparison register. ; ; LD A,(SWRDD0) ; Initialize the access pointer ; ; in the SmartWatch. ; ; Next, 64 consecutive write cycles are executed. These 64 ; write cycles are used only to gain access to the SmartWatch. ; LD B,2 ; Make two passes. UNLOCK: PUSH BC ; LD A,0C5H ; Begin the unlock sequence. CALL WRTCLK ; The odds of this pattern being LD A,3AH ; accidentally duplicated and CALL WRTCLK ; causing inadvertent entry to LD A,0A3H ; the SmartWatch is less than CALL WRTCLK ; 1 in 10^19. LD A,05CH CALL WRTCLK ; POP BC DJNZ UNLOCK ; Repeat one more time if needed. ; RET ; ; ------------------------------------------------------------- ; DB 'Copyright (C) 1986-1987 Robert Paddock.' ; ; ------------------------------------------------------------- ; ; WRTCLK: LD B,8 ; We must deal with 8 bits at a time. ; ; ; ------------------------------------------------------------- ; IF DS1216 ; If we are using the SmartWatch ; ; with nonvolatile RAM then we ; ; do thus: ; LD HL,SWRDD0 ; RTCWR: LD (HL),A ; Send out a bit on D0 RRCA ; shift right one place DJNZ RTCWR ; do all 8 bits. ; ENDIF ; DS1216 ; ; ------------------------------------------------------------- ; IF DSEPRM ; If we are using the EPROM version ; ; of the SmartWatch [DS1216E] then ; ; we do thus: LD C,A ; ; RTCWR: RRC C ; Is this bit a one or zero? JR C,WRTONE; Jump if its a one. ; LD A,(SWWRB0) ; Write a zero by reading. JR RTCWRL ; WRTONE: LD A,(SWWRB1) ; Write a one by reading. ; RTCWRL: DJNZ RTCWR ; Do all 8 bits. ; ; ENDIF ; DSEPRM ; ; ------------------------------------------------------------- ; RET ; ; ************************************************************* ; ; ; NOTE: This read routine will work for all of the devices ; as long as address line A2 is high when reading ; the DS1216E. ; ; RDCLK: LD HL,SWRDD0 XOR A ; Set all bits to zero. LD B,8 ; 8 bits make one byte. ; RTCRD: BIT 0,(HL) ; Does bit D0=0? JR Z,RDBITL ; Jump if the bit is ; ; already zero. SET 0,A ; Set the bit. ; RDBITL: RRCA ; Rotate right one bit. DJNZ RTCRD ; Do all of the bits. ; RET ; ; ------------------------------------------------------------- ; ; Smartwatch Register Information ; ; The SmartWatch information is contained in 8 registers, of 8 ; bits each, which are sequentially accessed one bit at a time ; after the 64-bit pattern recognition sequence has been ; completed. When updating the SmartWatch registers, each must be ; handled in groups of 8 bits. Writing and reading individual bits ; within a register could produce erroneous results. ; ; ; Data contained in the SmartWatch registers are always in ; binary coded decimal format (BCD). Reading and writing the ; registers is always accomplished by stepping through all 8 ; registers, starting with bit 0 of register 0 and ending with ; bit 7 of register 7. ; ; ; These read/write registers are defined below: ; ; ; Register, range (BCD), and bit number: ; ; 0: 00-99 7 = 0, 6-4 = 0.1 SEC, 3-0 = 0.01 SEC ; ; 1: 00-59 7 = 0, 6-4 = 10 SEC, 3-0 = SECONDS ; ; 2: 00-59 7 = 0, 6-4 = 10 MIN, 3-0 = MINUTES ; ; 3: 01-12/00-23 7 = 12/24, 6 = 0, 5 = 10|A/P, 4 = HR, 3-0 = HOUR ; ; 4: 01-07 7,6 & 3 = 0, 5 = OSC, 4 = RST, 2-0 = DAY ; ; 5: 01-31 7 & 6 = 0, 5-4 = 10 DATE, 3-0 = DATE ; ; 6: 01-12 7,6 & 5 = 0, 4 = 10 MONTH, 3-0 = MONTH ; ; 7: 00-99 7-4, 10 YEAR, 3-0 = YEAR ; ; ; ZERO BITS: ; ; Registers one trough six, contain one or more bits which ; will always read logical 0. When writing these locations, ; either a logical 1 or 0 is acceptable. ; ; ************************************************************* ; ; GETCLK: IF DS1216 LD A,(SWRDD0) ; Preserve the byte at LD (SVRAM),A ; 'SWRDD0' ENDIF ; DS1216 ; CALL ACCESS ; Select the clock, put 8 LD DE,FRACT ; bytes of data in the ; ; following order: ; CALL RDCLK ; Fractions of a second, LD (DE),A INC DE CALL RDCLK ; Seconds, LD (DE),A INC DE CALL RDCLK ; Minutes, LD (DE),A INC DE CALL RDCLK ; AM/PM, Hours, LD (DE),A INC DE CALL RDCLK ; OSC,RST,DAY, LD (DE),A INC DE CALL RDCLK ; Date (Day of month), LD (DE),A INC DE CALL RDCLK ; Month, LD (DE),A INC DE CALL RDCLK ; Years. LD (DE),A INC DE ; IF DS1216 LD A,(SVRAM) ; Restore the byte LD (SWRDD0),A ; at 'SWRDD0'. ENDIF ; DS1216 ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180FX LD BC,(LTCHIMG) ; Get back original latch CALL SETLATCH ; image, then write it. ENDIF ; SB180FX ; ; ------------------------------------------------------------- ; IF SB180 OR SB180FX LD A,(SVCBAR) ; Back to the normal memory map. OUT0 (CBAR),A ; ; ------------------------------------------------------------- ; LD A,(SVRCR) ; Turn the hardware DRAM OUT0 (RCR),A ; refresh back on. ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; ; Since some systems need the interrupts on (like the SB180) ; and some need them off, it is best that we put the interrupt ; enable bit back the way the system wants it. ; IF INTEI EI ENDIF ; INTEI ; ; ------------------------------------------------------------- ; LD A,(DAYS) ; Make sure there really is a ; ; SmartWatch present. ; LD HL,FRACT ; Point to BCD time. ; CP 0FFH ; All of the bits will be the same RET Z ; if there is no SmartWatch. OR A ; Return with the 'Z'-flag set RET Z ; if no SmartWatch is found. ; AND OSCOFF ; See if the SmartWatch has been set, CPL ; '0DFH' means that the SmartWatch is present OR A ; but not set. ; ; '0FFH', and the 'Z'-flag clear, means ; ; the SmartWatch is present and set. ; RET ; ; ------------------------------------------------------------- ; PUTCLK: IF DS1216 LD A,(SWRDD0) ; Preserve the byte at LD (SVRAM),A ; 'SWRDD0' ENDIF ; DS1216 ; CALL ACCESS ; Select the SmartWatch. LD DE,FRACT ; LD A,(DE) ; Fractions of a second, CALL WRTCLK INC DE LD A,(DE) ; Seconds, CALL WRTCLK INC DE LD A,(DE) ; Minutes, CALL WRTCLK INC DE LD A,(DE) ; AM/PM, Hours, CALL WRTCLK INC DE LD A,(DE) ; OSC,RST,Days, CALL WRTCLK INC DE LD A,(DE) ; Date, CALL WRTCLK INC DE LD A,(DE) ; Month, CALL WRTCLK INC DE LD A,(DE) ; Year. CALL WRTCLK ; IF DS1216 LD A,(SVRAM) ; Restore the byte LD (SWRDD0),A ; at 'SWRDD0'. ENDIF ; DS1216 ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180FX LD BC,(LTCHIMG) ; Get back original latch CALL SETLATCH ; image, then write it. ENDIF ; SB180FX ; ; ------------------------------------------------------------- ; IF SB180 OR SB180FX LD A,(SVCBAR) ; Back to the normal memory map. OUT0 (CBAR),A ; ; ------------------------------------------------------------- ; LD A,(SVRCR) ; DRAM Hardware refresh back on. OUT0 (RCR),A ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF INTEI EI ENDIF ; INTEI ; ; ------------------------------------------------------------- ; RET ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; ; IF SB180FX SETLATCH:XOR A ; Indicate that we want to DEC A ; write to the latch. ; LATCHVAL:LD HL,(BIOSLATCH) ; Go to the BIOS LATCHVAL JP (HL) ; routine. ENDIF ; SB180FX ; ; ; ; ; $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ ; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ; $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ ; ; ; The command section of SWTIME: ; START: LD HL,0 ; Save the stack pointer. ADD HL,SP ; (We can't use Z80 LD (STACK),HL ; instructions yet.) ; LD A,7FH ; Test for Z80 CPU. ADD A,A LD HL,Z80MSG ; Z80 Only error message. JP PO,MSGEXT ; Jump if not a Z80. ; ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180 OR SB180FX ; ; If this is a real Z-80 CPU, and not a HD64180/Z180 CPU. ; Then we can't run this version of SWTIME, because of the IO/MMU ; instructions. ; ; LD HL,Z180MSG ; Point to '180 only' message. SCF ; Set the carry flag. TST A ; This will clear the carry flag ; ; on the HD64180/Z180, but it will JP C,MSGEXT ; remain set on the Z-80. ; ; ; On a Zilog Z-80, the 'TST A' (ED3CH) instruction is a NOP. ; The ED3CH op-code is an undocumented Z-80 instruction, so it is ; a gamble using it. Does any one have any other ideas, that ; don't need to resort to 'tricks'? ; ; Keep in mind this code may only be a problem if the ; SB180(FX) equate is set when the code is assembled, AND THEN we ; try to run this program on a Z-80. [I kept erroneously doing ; this when I was developing this program, that is why the code is ; here at all.] ; ; ENDIF ; SB180 OR SB180FX ; ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; ; At long last we can get down to doing some useful work. ; LD SP,STACK ; Set up our own stack. ; ; CALL GETCLK ; Get all of the info from the ; ; SmartWatch. ; LD HL,NOSWPR ; Jump if no SmartWatch is present JP Z,MSGEXT ; in the system. ; LD C,A ; Save the watch status code. ; LD A,(FCB+1) ; What should we do? ; AND 01011111B ; Make it upper case. ; CP 'S' ; Command to set the JP Z,SETTIM ; SmartWatch? ; LD B,A ; Save the command for a while. ; LD A,C ; If the command was not the set command LD HL,SWNSET ; then check to see that the CP OSCON ; SmartWatch is already set, if JP Z,MSGEXT ; it is not set, then print an error ; ; message, then the help message. ; LD A,B ; Get back the users command. OR A ; print out the time? JP Z,TELTIM ; Jump if yes. CP 'R' ; Print out the time continuously. JP Z,REPTIM ; Jump if yes. CP 'O' ; Turn the SmartWatch off? JP Z,TUROFF ; Jump if yes. ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180 OR SB180FX CP 'C' ; Clear the elapsed time clock. JP Z,CLRETM CP 'X' ; Display the elapsed time clock. JP Z,DISETM CP 'T' ; Transfer the SmartWatch time JP Z,TRNSFR ; to the BIOS clock. ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; HELP: LD HL,HLPMSG ; HELP !!! ; MSGEXT: CALL PSTR ; Print the string pointed to ; ; by HL. ; EXIT: LD HL,(STACK) ; (Only use 8080 instructions LD SP,HL ; here.) RET ; ; ************************************************************* ; GETTIM: LD A,(HL) INC HL SUB '0' ; Remove the ASCII bias. CP 9+1 ; 0->9? JP NC,HELP ; If it is not, then print ; ; the help message. SWAP ; Swap the nibbles, AND 0F0H ; and do the other nibble. LD C,A ; Save this binary nibble. ; LD A,(HL) ; Do the same as above. INC HL SUB '0' CP 9+1 JP NC,HELP ; OR C ; Make the two BCD digits, ; ; one 8 bit binary value. RET ; ; ------------------------------------------------------------- ; ; Set the time: ; SETTIM: LD A,(TBUFF) ; Read the command buffer. CP 18 ; ' S hhmmssMMDDYYdm'? JP NC,HELP LD HL,TBUFF+4 CALL GETTIM CP 23H+1 ; Check for valid range JP NC,HELP ; (We'll check 12-hours latter). LD (HRS),A ; Store the Hours. ; CALL GETTIM ; Minutes CP 59H+1 JP NC,HELP LD (MIN),A ; CALL GETTIM ; Seconds CP 59H+1 JP NC,HELP LD (SEC),A ; CALL GETTIM ; Month CP 12H+1 JP NC,HELP LD (MON),A ; CALL GETTIM ; Day of month CP 31H+1 JP NC,HELP LD (DATE),A ; CALL GETTIM ; Year CP 99H+1 JP NC,HELP LD (YEAR),A ; LD A,(HL) ; Days INC HL CALL CATH ; Convert ASCII to HEX. CP 7+1 JP NC,HELP OR RSTPIN ; Ignore the reset pin (Pin #1). LD (DAYS),A ; ; AM-PM/12/24/ MODE: ; ; Bit 7 of the hours register is defined as the 12- or 24- ; hour mode select bit. When high, the 12-hour mode is selected. ; In the 12-hour mode, bit 5 is the AM/PM bit with logic high ; being PM. In the 24-hour mode, bit 5 is the second 10-hours ; bit (00-23 hours). ; LD A,(HL) ; 'A'm,'P'm or 24-hour? AND 01011111B ; Make it upper case. JR Z,IS24HR ; Jump if it is 24 hour time. ; CP 'A' ; AM? JR NZ,TRYPM LD C,10000000B ; Yes: Set the 12-hour mode JR IS12HR ; bit. ; TRYPM: CP 'P' ; PM? JP NZ,HELP LD C,10100000B ; Yes: Set the 12-hour, and the ; ; PM mode bits. ; IS12HR: LD A,(HRS) ; Now we'll check the 12 hour CP 12H+1 ; time. JP NC,HELP OR C ; Put the mode bits, and the hours LD (HRS),A ; together, and save them. ; IS24HR: CALL PUTCLK ; Write all of the info to the ; ; SmartWatch. ; ; Fall trough to Tell Time. ; ; ------------------------------------------------------------- ; ; Tell the Time: ; TELTIM: CALL GETCLK ; Get the info from the ; ; SmartWatch. CALL ASCTIM ; Print out the time JP MSGEXT ; on the way back to the ; ; operating system. ; ; ------------------------------------------------------------- ; ; ; REPTIM: XOR A ; Print the time now! DEC A LD (LSTSEC),A ; Not a second from now. ; TREPLP: CALL CONDIN ; Check for abort by the user, JP NZ,EXIT ; on the console. ; If there was a abort request then ; ; go back to the operating system. ; CALL GETCLK ; Get the time from the ; ; SmartWatch. ; LD A,(LSTSEC) ; Is this a new second? LD C,A LD A,(SEC) ; Read the current second CP C JR Z,TREPLP ; Jump if its not. ; LD (LSTSEC),A ; Save for the next second. ; CALL ASCTIM ; Convert from BCD to ASCII CALL PSTR ; and print it on the ; ; console. ; LD A,CR ; Get ready to over-write CALL COUT ; this time, with the time ; ; a second from now. ; JR TREPLP ; On to the next second. ; ; ; ------------------------------------------------------------- ; ; Turn off, the SmartWatch for long term storage. ; TUROFF: LD A,(DAYS) OR OSCRST ; Turn the SmartWatch off. LD (DAYS),A CALL PUTCLK ; Write the info. ; LD HL,SWSOFF ; Tell'em that the SmartWatch JP MSGEXT ; is now off. ; ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; ; The following are to maintain compatibility with the ; SB180(FX)'s, software clock. ; IF SB180 OR SB180FX ; TRNSFR: CALL GETCLK ; Get the info from the SmartWatch. ; LD A,(HRS) ; If in the 24 hour mode, then we BIT 7,A ; have no problem. JR Z,XFERTM ; AND 3FH ; 12 hour mode. Now things get messy. ; CP 12H ; 12 AM ? JR NZ,NO12AM ; XOR A ; YES: 12 AM = 00 HOURS JR XFERTM ; NO12AM: BIT 5,A ; If it is 01-11 AM then it is ok JR Z,XFERTM ; as it is. ; CP 32H ; 12 PM ? JR NZ,NO12PM ; AND 1FH ; YES: 12 PM = 12 HOURS JR XFERTM ; NO12PM: AND 1FH ; We now know it is PM. ADD A,12 ; Convert to 13-23 DAA ; Back to BCD. AND 3FH ; XFERTM: CALL BCD2BIN ; Transfer the time from ; ; the SmartWatch to LD (WHOUR),A ; the BIOS clock. ; LD A,(MIN) ; The SmartWatch time is in CALL BCD2BIN ; BCD, the BIOS clock wants LD (WMIN),A ; the time in binary. LD A,(SEC) CALL BCD2BIN LD (WSEC),A CALL WRWALL ; Write the date to the BIOS clock. JP TELTIM ; Confirm that it was done. ; ; ############################################################# ; ; NOTE: This section of code (appearing between the ; '###' lines) is taken from the file 'TIME.Z80', by Joe ; Wright, as supplied with the SB180. It is used by permission. ; 'TIME.Z80' is copyrighted by Joe Wright, 1985. ; ; CLRETM: XOR A LD (EHOURS),A LD (EMINS),A LD (ESECS),A CALL WRREAL ; DISETM: CALL RDREAL ; CALL PRINT DB CR,' RTC: ',0 LD HL,EHOURS ; TIMEOUT: LD A,(HL) DEC HL CALL BIN2BCD CALL PA2HC ; LD A,':' ; I (RLP) added these two CALL COUT ; lines. Comment, or NOP them ; ; to be 100% compatible with ; ; 'TIME.Z80'. LD A,(HL) DEC HL CALL BIN2BCD CALL PA2HC LD A,':' CALL COUT LD A,(HL) CALL BIN2BCD CALL PA2HC ; JP EXIT ; TIME: LD HL,(BIOS+1) LD L,36H ; Offset to the BIOS clock. JP (HL) RDREAL: OR 255 ; Read flag. PUSH AF LD BC,3 PUSH BC LD DE,1 JR CLOCK WRREAL: XOR A ; Write flag. PUSH AF LD BC,3 PUSH BC LD DE,1 JR CLOCK RDWALL: OR 255 ; Read flag. PUSH AF LD BC,3 ; Three bytes. PUSH BC LD DE,4 ; Offset to wallclock. JR CLOCK WRWALL: XOR A ; Write flag. PUSH AF LD BC,3 ; Three bytes. PUSH BC LD DE,4 ; Offset to wallclock. CLOCK: LD HL,ETENTHS ADD HL,DE ; Add offset. PUSH HL CALL TIME ; Point HL to timer string ADD HL,DE ; add offset. POP DE POP BC ; Get byte count, POP AF ; get direction. JR NZ,CLOCK0 EX DE,HL CLOCK0: DI LDIR ; Move it. EI RET ; ; ; BIN2BCD will convert a 0-99 binary number to 0-99 BCD number. ; call with (A)=binary number 0-99. (A)=0-99 BCD on exit. ; BIN2BCD:OR A ; BCD 0 = Binary 0, RET Z ; so return. LD B,A ; Conversion counter. XOR A ; Clear 'A'. ; BINLOP: INC A ; Add one. DAA ; Binary to BCD. DJNZ BINLOP ; All converted? ; RET ; ; ############################################################# ; ; ; BCD to binary converter ; [from BYE504] ; ; This routine will convert an 8 bit BCD number (0-99) to binary. ; the routine returns with the binary number in the 'A' register. ; BCD2BIN: LD E,A ; Save original byte. AND 0FH LD D,A ; Save low nibble. LD A,E AND 0F0H ; Mask LSN. RRCA ; x2 LD E,A RRCA ; x4 RRCA ; x8 ADD A,E ; x10 ADD A,D ; Low nibble. RET ; ; ; ------------------------------------------------------------- ; ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; ; Convert SmartWatch BCD info to ASCII text. ; ASCTIM: LD HL,TIMSTR ; Point to the ASCII time. ; ; LD A,(HRS) BIT 7,A ; 12 or 24 time? JR Z,MILTIM ; Jump if using 24 time. ; AND 1FH ; Strip unneeded bits, 12 hr mode. ; MILTIM: AND 3FH ; Strip unneeded bits, 24 hr mode. CALL BCDASC LD (HL),':' INC HL LD A,(MIN) CALL BCDASC LD (HL),':' INC HL LD A,(SEC) CALL BCDASC LD (HL),' ' INC HL ; LD A,(HRS) ; If in 24 mode BIT 7,A ; then don't print JR Z,NOAMPM ; 'AM' or 'PM'. ; LD (HL),'A' ; Assume its AM. BIT 5,A ; Find out if it is really JR Z,WASAM ; AM. LD (HL),'P' ; No, its PM. ; WASAM: INC HL LD (HL),'M' INC HL LD (HL),' ' INC HL ; NOAMPM: IF EDATE ; LD A,(DATE) ; dd/mm CALL BCDASC LD (HL),'/' INC HL LD A,(MON) CALL BCDASC ; ELSE ; LD A,(MON) ; mm/dd CALL BCDASC LD (HL),'/' INC HL LD A,(DATE) CALL BCDASC ; ENDIF ; EDATE ; ; LD (HL),'/' ; /yy INC HL LD A,(YEAR) CALL BCDASC ; ; IF WEKDAY ; Print the day of the week 'Sun, Mon...' LD (HL),' ' INC HL PUSH HL LD A,(DAYS) AND 7 DEC A ; Adjust for 0-6. LD E,A LD D,0 ; Clear top. LD HL,DAYTAB ; Get address of table, ADD HL,DE ; table + 3 * (HL) = name. ADD HL,DE ADD HL,DE LD BC,3 ; Move name into buffer. POP DE LDIR EX DE,HL ENDIF ; WEKDAY ; LD (HL),0 ; End marker for string print. ; LD HL,TIMSTR ; Send the start of the string RET ; then back to the caller. ; ; ------------------------------------------------------------- ; ; Convert a BCD number to ASCII. ; BCDASC: PUSH AF ; SWAP ; Do the upper nibble first AND 0FH OR '0' ; Add in the ASCII bias. LD (HL),A INC HL ; POP AF ; Now the lower nibble AND 0FH OR '0' LD (HL),A INC HL ; RET ; ; ------------------------------------------------------------- ; Z80MSG: DB CR,LF,CR,LF DB '*** SWTIME, will not work on the 8080 or the 8085' DB ', sorry... ***' DB CR,LF,CR,LF,0 ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180 OR SB180FX Z180MSG:DB CR,LF,CR,LF DB '*** This version of SWTIME is configured for ' DB 'the HD64180/Z180.',CR,LF DB ' Reassemble to use on the Z80. ***' DB CR,LF,CR,LF,0 ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; SWSOFF: DB CR,LF,CR,LF DB '*** The SmartWatch is now turned off. ***' DB CR,LF,CR,LF,0 ; ; ------------------------------------------------------------- ; NOSWPR: DB CR,LF,CR,LF DB '*** No SmartWatch is present. ***' ; ; Fall trough to the "Not Set" message. If there is no ; SmartWatch present then by default it won't be set. ; ; SWNSET: DB CR,LF DB '*** The SmartWatch is not set. ***' DB CR,LF ; ; If the SmartWatch is "Not Set" then fall trough to the ; "Help" screen, so that we can get instructions on how to set the ; SmartWatch. ; HLPMSG: DB CR,LF DB ' SWTIME VER:' ; DB MAIN +'0', '.' DB VERS /10+'0', VERS MOD 10+'0', ' - ' DB VMONTH /10+'0', VMONTH MOD 10+'0', '/' DB VDAY /10+'0', VDAY MOD 10+'0', '/' DB VYEAR /10+'0', VYEAR MOD 10+'0' ; DB CR,LF DB ' Copyright (C) 1986-1987 by Robert Paddock.' ; DB CR,LF,CR,LF DB ' This program allows setting and reading of the:' DB CR,LF DB ' Dallas Semiconductor "SmartWatch".' DB CR,LF,CR,LF ; DB ' Usage:',CR,LF,CR,LF ; DB ' SWTIME<CR> Will display the date and time of day.' ; DB CR,LF DB ' SWTIME R<CR> Displays the time & date repeatedly.' ; DB CR,LF DB ' SWTIME O<CR> Turn the SmartWatch off, for long term storage.' ; DB CR,LF DB ' SWTIME S hhmmssMMDDYYdm<CR> Will set the time, date and day.' DB CR,LF,CR,LF DB ' Where: hh=Hours (00-23/00-12), ' DB 'mm=Minutes (00-59), ' DB 'ss=Seconds (00-59), ' DB CR,LF DB ' MM=Months (01-12), ' DB 'DD=Day of month (01-31), ' DB 'YY=Year (00-99),' DB CR,LF DB ' d=Day of week (1=Sunday, 7=Saturday),' DB CR,LF DB ' m=Mode: "A" = AM, "P" = PM, ' DB 'omit for 24 hour format.' DB CR,LF,CR,LF ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180 OR SB180FX DB ' SWTIME C<CR> Clear the elapsed time clock.' DB CR,LF DB ' SWTIME X<CR> Display the elapsed time clock.' DB CR,LF DB ' SWTIME T<CR> Transfer the time of day from the' DB CR,LF DB ' SmartWatch to the SB180 BIOS clock.' DB CR,LF ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; DB 0 ; end marker for string print ; ; ; ------------------------------------------------------------- ; IF WEKDAY DAYTAB: DB 'SUN' ; Day of week table. DB 'MON' DB 'TUE' DB 'WED' DB 'THU' DB 'FRI' DB 'SAT' ENDIF ; WEKDAY ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180FX LTCHIMG: DS 2 ; Image of SB180FX latch BIOSLATCH: DS 2 ; Address of BIOS LATCHVAL routine ENDIF ; SB180FX ; ; ------------------------------------------------------------- ; IF SB180 OR SB180FX SVCBAR: DS 1 ; Save the MMU register CBAR. SVRCR: DS 1 ; Save the refresh register RCR. ; ETENTHS:DS 1 ; Elapsed time clock. ESECS: DS 1 EMINS: DS 1 EHOURS: DS 1 ; WSEC: DS 1 ; 'Wall clock' (Real time of day). WMIN: DS 1 WHOUR: DS 1 ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF DS1216 SVRAM: DS 1 ; Place to save the RAM byte at SWRDD0. ENDIF ; DS1216 ; ; LSTSEC: DS 1 ; Place to save the 'Last Second'. ; FRACT: DS 1 ; Fractions of a second SEC: DS 1 ; Seconds MIN: DS 1 ; Minutes HRS: DS 1 ; Hours DAYS: DS 1 ; Days DATE: DS 1 ; Date MON: DS 1 ; Month YEAR: DS 1 ; Years ; TIMSTR: DS 128 ; Place to store the ASCII time string, ; ; (and stack head room). STACK: DS 2 ; Place to save the operating systems ; ; stack pointer. ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; IF SB180 OR SB180FX .DEPHASE ; End of logical phase block. ENDIF ; SB180 OR SB180FX ; ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ; LSTADR EQU $ ; Last address of code that may ; ; need transferred. ; ; ; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ; @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ ; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ; ; ; Here are some interesting things related to 'Time': ; ; Exactly what is this thing called 'Time' anyway? ; ; The following documents are available from the ; National Technical Information Service (NTIS), an agency of ; the U.S. Department of Commerce: ; ; 5285 Port Royal Road, ; Springfield, VA 22161: ; (703) 487-4650 ; ; JPRS: 45238, 2 May 1968 ; ; "The possibility of the Experimental Study of the Properties ; of Time; by N. Kozyrev" ; ; $9.95 + $3 Shipping ; ; ----------------------------------------------------------------- ; ; Cesium atoms, which are used in Atomic-Clocks, have a ; resonant frequency of 9.192631770 GHz. ; ; ----------------------------------------------------------------- ; ; The speed of light according to by Dr. Taylor of the National ; Bureau of Standards (USA) [on 11/14/85, at 8:35 AM] was: ; ; 299,792,458 Meters per Second ; [186,282.3971 Miles per second] ; ; These measurements were made in October of 1983. ; ; ; "The Meter has been redefined using this number ; [299,792,458]." ; ; From the Sixth Edition of "Modern College Physics" by ; Harvey E. White: ; ; The standard meter {1},is defined in terms of the ; wavelength of light from a source containing KRYPTON GAS ; (chemical element 36): ; ; 1 meter = 1,650,763.73 wavelengths ; (For orange light of krypton) ; ; {1}: Adopted as the International legal standard of ; length, October 14, 1960, by the General Conference on Weights ; and Measures in Paris, France. ; ; ---------------------------------------------------------------- ; ; Light-year: The distance traveled by light in one year. ; ; There are 9.454254955 * 10^12 millimeters in one light- ; year. ; ; ----------------------------------------------------------------- ; ; A large (6' by 4') multi-color map showing all 25 time ; zones of the planet Earth, is available from the U.S. ; Defense Mapping Agency, request: ; ; "Standard Time Zone Chart of the World" ; Chart #76; DMA Stock #WOBZC76 ; $5.50 ; ; Information on maps and charts produced by the Defense ; Mapping Agency, is available from: ; ; ; Defense Mapping Agency ; Office of Distribution Services, U.S. Department of Defense ; Attn: DDCP ; Washington, DC 20315-0020 ; (202)-227-2816 ; ; All orders must be pre-paid: ; Make checks payable to "Treasurer of the United States" ; ; [ The quality of this map, is well worth the price. It ; takes about ten weeks to get it. The DMA is cheep, not fast. ] ; ; ------------------------------------------------------------- ; ; 00:00:00 and 24:00:00 are interchangeable. 24:00:00 is ; associated with the date of the day ending, 00:00:00 with the ; day just starting. ; ; ; ------------------------------------------------------------- ; ; One Side Real Day = 23:56:04 ; ; ------------------------------------------------------------- ; ; At a Horological Exhibit you could see examples of clocks ; and watches representing America, England, France, Austria, ; Japan, Holland and others during the 18th, 19th, and 20th ; Century. ; ; You might see the work of: Ely Terry, Abel Chandler, Aron ; Crane, Livi and Able Hutchins, Joseph Ives, Chauncy Jerome, Asa ; Munger, Chas Kirk, Henri Robert, Antide Janvier, Seth Thomas, ; Abner Jones, Geo. Solliday, David Wood, Simon Willard Jr, The ; Howards. ; ; ------------------------------------------------------------- ; ; Julian Dates: Julian dates as used by astronomers take ; noon, 1 January 4713 B.C. as the base date (astronomers count ; days from noon to noon). CP/M-3 uses a base data of 1 January ; 1978. ; ; Julian Dates, can be usefully applied in computer programs. ; Particularly for real-time control of processes that need to ; handle long term event scheduling. ; ; ; See "Julian Dates For Microcomputers" by Gordon King; Dr ; Dobb's Journal, Number 80, June 1983, for code on how to use ; Julian Dates. ; ; ------------------------------------------------------------- ; ; Ephemeris Time: ; ; "Ephemeris Time is based on idealized motions of the Sun and ; Moon and was introduced into the astronomical tables on January ; 1, 1960 to free astronomical calculations from the effect of ; irregularities of the Earth's rotation. The irregularities ; apparently show up in GMT(UT) but not UTC which is based on ; atomic clocks and broadcast by WWV. Not to worry - all these ; times differ from each other by less than a second." ; ; -- 03/11/87 SYSOP [ of NOAA] ; ; ------------------------------------------------------------- ; ; The END