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Z8530 SCC Samples
ref. file Z8530_SCCsamples.zip
After downloading, unzip using WinZIP or a similar
utility.
Resulting file is Z8530ROUTNS.SHK
After transferring Z8530ROUTNS.SHK to your Apple IIgs,
unShrink using GS.ShrinkIt ("GSHK", "ShrinkIt.GS", ...).
The enclosed file will show you how to access the Z8530 Serial Communications
controller in the Apple IIgs, without "breaking" the system in any way. These
routines are taken from a working development version of Warp Six BBS version
9.0, a shareware program. Currently version 8.9.1 is released; version 9.0 is
still under development. Warp Six is copyright, but the enclosed routines are
dedicated to the public domain, so you can use them in any way you wish.
The code is well commented, so read it and enjoy it. It's in Merlin 16+
format.
You will also want a copy of the Zilog Z8030/Z8530 SCC Technical Manual,
published by Zilog. Here are some of their phone numbers from the back of
that same manual. Some of these may have changed, so if you can't get
through, try directory assistance at (area code) 555-1212:
Toronto, Canada (416) 673-0634
Campbell, CA, USA (408) 370-8120
Dallas, TX, USA (214) 987-9987
Munich, Germany 49-89-672-045
Tokyo, Japan 81-3-587-0528
Kowloon, Hong Kong 852-7238979
Maidenhead, UK 44-628-392-00
Note: should you find any problems with the source code, please let me know;
however, take note that I don't warrant they are bullet-proof.
---
GEnie: J.FERR CompuServe: 73057,2455 | Jim Ferr, 26-95 DeCarie Circle
Internet: 73057.2455@compuserve.com | Etobicoke, Ontario M9B 3J5 CANADA
____________
* Sample IIGS source code by Jim Ferr.
* I hereby place this code in the public domain.
* March 19, 1992.
* Apple IIgs Z8530 registers and constants
GSCMDB = $C038
GSCMDA = $C039
GSDATAB = $C03A
GSDATAA = $C03B
WR11A = %11010000 ;init wr11 in Ch A
WR11B = %01010000 ;init wr11 in Ch B
;crystal not used by Ch B
;3.6864MHz external crystal
;Rx/Tx clock source = BRG
;TRxC is an input (tied to cts)
;bits 1 and 0 insignificant
RESETCHA = %11010001 ;constant to reset Ch A
RESETCHB = %01010001 ;constant to reset Ch B
* This little routine intercepts the Interrupt
* Manager vector at $E1/0010 or wherever it may
* be in the future, pointing it to our IRQIN
* routine. We save the original manager's address
* so we can pass interrupts that aren't ours to
* the slow-poke firmware.
XC
XC
ALLOCATE SEI
CLC ;go to native mode
XCE
REP #$30 ;with 16-bit registers
MX %00
PEA $0000 ;push long
PEA $0000
PEA $0004 ;Interrupt Manager refnum
LDX #$1103 ;GetVector
JSL $E10000
PLA ;save orgmgr address
STA ORGMGR
PLA
STA ORGMGR+2
PEA $0004 ;Interrupt Manager refnum
PEA $0000 ;bank zero
PEA #IRQIN ;our manager address
LDX #$1003 ;SetVector
JSL $E10000
SEC ;emulation mode
XCE
SEP #$30 ;with 8-bit registers
MX %11
CLI
RTS
XC OFF
XC
XC ; set to full 65816 opcodes
MX %11 ; set Merlin 16+ to 8-bit mode
* Data carrier detect flag for main program
DCDSTATE DS 1 ;flag. Non-zero means no DCD.
* Default baud rate
BAUD DFB 7 ;1=300, 2=1200, 3=2400
;4=4800, 5=9600, 6=19200
;7=38400, 8=57600.
* Interrupt Manager
*
* Here is where we get the irqs and steal ours from
* the teeth of the firmware, as it were. If the irq
* isn't ours, we exit to the firmware. If it is ours,
* we process it and RTI (Return from interrupt).
LST ON
IRQIN CLC ;emulation or native mode?
LST OFF
XCE ;enter native mode
BCC :NATIVE ;was already in native mode
* Emulation mode entry
SEC ;was in emulation mode, so
XCE ;lets go back to it.
PHP ;save status for firmware
PHA ;save registers
PHX
PHY
LDA #$FF
STA :FIRST ;first time through flag
STA :EMULATE ;emulation mode flag
BRA :IRQTEST ;check if our irq
* Native mode entry
:NATIVE PHP ;save status for firmware
REP #$30 ;16-bit mode
MX %00
PHA ;save all registers
PHX
PHY
PHB ;save DBR
PEA $0000
PLB ;switch in data bank zero
PLB ;pull 16 bits
SEP #$30 ;8-bit mode
MX %11
LDA #$FF
STA :FIRST ;first time through flag
STZ :EMULATE ;kill emulation mode flag
;fall through to :IRQTEST
* Test if irq pending on SCC Channel B
:IRQTEST LDX #3
STX GSCMDA
LDA GSCMDA ;read rr3 ch A ip bits
AND #%00000101 ;check for Rx and ext/stat
;in Ch B only.
BNE :GETINT
JMP :EXIT
:GETINT STZ :FIRST ;is definitely our irq
LDX #2
STX GSCMDB
LDA GSCMDB ;get vector from rr2B
AND #%01110000 ;examine bits 6-5-4
CMP #%00100000 ;Rx?
BEQ :RX
CMP #%01100000 ;special?
BEQ :SPECIAL
;if not, must be exint.
* Handle external status interrupts
:EXINT LDA #%00010000 ;reset exint pending
STA GSCMDB
LDA GSCMDB
* The two lines below are commented out because this
* driver assumes carrier detect is in GPi.
* AND #%00100000 ;get CTS/HSKi bit
* EOR #%00100000 ;flip the CTS/HSKi bit
AND #%00001000 ;get DCD/GPi bit
EOR #%00001000 ;flip the DCD/GPi bit
STA DCDSTATE ;non-zero means offline
BRA :IRQTEST
* Special condition (error)
:SPECIAL LDX #1 ;rr1
STX GSCMDB
LDA GSCMDB
TAX
AND #%01000000 ;framing error?
BNE :BAD
TXA
AND #%00100000 ;overrun? (latched)
BEQ :BAD
LDA #%00110000 ;error reset command
STA GSCMDB ;to clear latched error.
BRA :IRQTEST
:BAD LDA GSDATAB ;eat bad character!
BRA :IRQTEST
* Get received character
:RX LDA GSDATAB ;get good char
*** STUFF DELETED (BUFFER THE CHARACTER)
BRA :IRQTEST ;test for more!
:FIRST DS 1 ;flag for first time thru
:EMULATE DS 1 ;flag/ were we in emulation
;mode or native mode.
* The ONLY exit (from IRQIN)
:EXIT BIT :EMULATE
BPL :EXIT3
* Emulation mode; irq exit routine
:EXIT1 BIT :FIRST ;first time through?
BMI :EXIT2 ;if so, not our irq
PLY
PLX
PLA
PLP ;restore status
RTI ;was ours.
:EXIT2 PLY
PLX
PLA
PLP
BRA :JUMP ;go to the firmware
* Native mode, irq exit routine
:EXIT3 BIT :FIRST ;first time through?
BMI :EXIT4 ;if so, not our irq
REP #$30 ;16-bit mode
MX %00
PLB ;restore data bank register
PLY ;restore Y
PLX ;restore X
PLA ;restore A
PLP ;restore original status
RTI ;return from interrupt
:EXIT4 REP #$30 ;16-bit mode
PLB ;restore data bank register
PLY ;restore Y
PLX ;restore X
PLA ;restore A
PLP ;restore original status
MX %11
* JML to firmware's handler (and let it worry about
* this interrupt.)
:JUMP DFB $5C ;JML
LST ON
ORGMGR DS 4 ;to original manager address
LST OFF
* This routine removes our intercept of the vector
* and restores the original firmware vector.
REMOVE SEI
JSR DISABLE ;disable modem port!
;and put it back in state
;the serial port firmware
;can handle.
CLC
XCE
REP #$30 ;full 16-bit mode
PEA $0004 ;Interrupt Manager refnum
LDA ORGMGR+2
PHA
LDA ORGMGR ;original manager address
PHA
LDX #$1003 ;SetVector
JSL $E10000
SEC ;emulation mode
XCE
SEP #$30
MX %11
CLI
RTS
* INITGS: initialize the Modem Port
* (Channel B is modem port, A is printer port)
INITGS SEI
LDA GSCMDB ;hit rr0 once to sync up
LDX #9 ;wr9
LDA #RESETCHB ;load constant to reset Ch B
;for Ch A, use RESETCHA
STX GSCMDB
STA GSCMDB
NOP ;SCC needs 11 pclck to recover
LDX #4 ;wr4
LDA #%01000100 ;X16 clock mode,
STX GSCMDB ;1 stop bit, no parity
STA GSCMDB ;could be 1.5 or 2 stop bits
;1.5 set bits 3,2 to 1,0
;2 set bits 3,2 to 1,1
LDX #3 ;wr3
LDA #%11000000 ;8 data bits, receiver disabled
STX GSCMDB ;could be 7 or 6 or 5 data bits
STA GSCMDB ;for 8 bits, bits 7,6 = 1,1
LDX #5 ;wr5
LDA #%01100010 ;DTR enabled 0=/HIGH, 8 data bits
STX GSCMDB ;no BRK, xmit disabled, no SDLC
STA GSCMDB ;RTS *MUST* be disabled, no crc
LDX #11 ;wr11
LDA #WR11B ;load constant to write
;use #WR11A for channel A
STX GSCMDB
STA GSCMDB
JSR TIMECON ;set up wr12 and wr13
;to set baud rate.
LDX #14 ;wr14
LDA #%00000000 ;null cmd, no loopback
STX GSCMDB ;no echo, /DTR follows wr5
STA GSCMDB ;BRG source is XTAL or RTxC
* Enables
ORA #%00000001 ;enable baud rate gen
LDX #14 ;wr14
STX GSCMDB
STA GSCMDB ;write value
LDA #%11000001 ;8 data bits, Rx enable
LDX #3
STX GSCMDB
STA GSCMDB ;write value
LDA #%01101010 ;DTR enabled; Tx enable
LDX #5
STX GSCMDB
STA GSCMDB ;write value
* Enable Interrupts
LDX #15 ;wr15
* The next line is commented out. This driver wants
* interrupts when GPi changes state, ie. the user
* on the BBS may have hung up. You can write a 0
* to this register if you don't need any external
* status interrupts. Then in the IRQIN routine you
* won't need handling for overruns; they won't be
* latched. See the Zilog Tech Ref. for details.
* LDA #%00100000 ;allow ext. int. on CTS/HSKi
LDA #%00001000 ;allow ext. int. on DCD/GPi
STX GSCMDB
STA GSCMDB
LDX #0
LDA #%00010000 ;reset ext. stat. ints.
STX GSCMDB
STA GSCMDB ;write it twice
STX GSCMDB
STA GSCMDB
LDX #1 ;wr1
LDA #%00010001 ;Wait Request disabled
STX GSCMDB ;allow IRQs on Rx all & ext. stat
STA GSCMDB ;No transmit interrupts (b1)
LDX #9 ;re-write wr9
LDA #%00011001 ;set Master Interrupt Enable
STX GSCMDB ;this value gives us vector
STA GSCMDB ;information with each irq,
;in vector bits 6-5-4,
;also including status.
* The vector bits are not used by firmware and IIGS
* TechNote #18. But they make irq handling easier.
;(See IRQIN routine.)
CLI
RTS ;we're done!
* DISABLE: ensure serial port IRQ's turned off
* (DTR unaffected; use HANGUP or GSDTR)
* This routine puts the port in normal firmware
* state, with no interrupts possible.
DISABLE SEI
LDA #%00000010 ;disable MIE temporarily
LDX #9
STX GSCMDB
STA GSCMDB
* Interrupt Status
LDX #1 ;wr1
LDA #%00000000 ;no DMA, no interrupts
STX GSCMDB
STA GSCMDB
LDA GSDATAB ;eat any character waiting
LDX #0 ;wr0
LDA #%00010000 ;clear any ext ints
STX GSCMDB
STA GSCMDB
STX GSCMDB ;write it twice
STA GSCMDB
LDA #%00001010 ;reset MIE for firmware use
LDX #9
STX GSCMDB
STA GSCMDB
CLI
RTS
* TIMECON: Set time constant bytes in wr12 & wr13
* (In other words, set the baud rate.)
TIMECON LDY BAUD
LDA #12
STA GSCMDB
LDA BAUDL-1,Y ;load time constant low
STA GSCMDB
LDA #13
STA GSCMDB
LDA BAUDH-1,Y ;load time constant high
STA GSCMDB
RTS
* Table of values for different baud rates. There is
* a low byte and a high byte table.
BAUDL DFB 126 ;300 bps (1)
DFB 94 ;1200 (2)
DFB 46 ;2400 (3)
DFB 22 ;4800 (4)
DFB 10 ;9600 (5)
DFB 4 ;19200 (6)
DFB 1 ;38400 (7)
DFB 0 ;57600 (8)
BAUDH DFB 1 ;300 bps (1)
DFB 0 ;1200 (2)
DFB 0 ;2400 (3)
DFB 0 ;4800 (4)
DFB 0 ;9600 (5)
DFB 0 ;19200 (6)
DFB 0 ;38400 (7)
DFB 0 ;57600 (8)
* DOBAUD: Set baud rate without resetting entire 8530
* (Stop clock, set time constant, restart clock)
DOBAUD SEI
LDA #0 ;disable BRG (stop clock)
LDX #14 ;wr14
STX GSCMDB
STA GSCMDB ;write it
JSR TIMECON ;set time constant bytes
LDA #%00000001 ;re-enable BRG
LDX #14
STX GSCMDB
STA GSCMDB
:EXIT CLI
RTS
* MOUT: send character in A to modem, regardless of
* carrier state. Preserves all registers.
MOUT STA :TEMPA
STX :TEMPX
:SEND LDA GSCMDB ;rr0
TAX
AND #%00000100 ;test bit 2 (hardware handshaking)
BEQ :SEND
TXA
AND #%00100000 ;test bit 5 (ready to send?)
BEQ :SEND
:EXIT0 LDA :TEMPA ;get char to send
STA GSDATAB ;send the character
:EXIT LDX :TEMPX
LDA :TEMPA
RTS
:TEMPA DS 1
:TEMPX DS 1
* Code for checking if data in buffer deleted
* CLRMBUF: clear mbuf.
CLRMBUF SEI
** stuff deleted (fix buffer pointers)
LDA GSDATAB ensure no data in SCC
LDA GSDATAB by reading data 3 times
LDA GSDATAB (it has a 3 byte fifo)
:EXIT CLI
RTS
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