REM > AP1v1311.src
REM Source for Electron Plus 1 Support
:
ON ERROR REPORT:PRINT" at line ";ERL:END
IF PAGE>&8000:SYS "OS_GetEnv"TOA$:IFLEFT$(A$,5)<>"B6502":OSCLI"B6502"+MID$(A$,INSTR(A$," "))
DEFFNif(A%):IFA%:z%=-1:=opt% ELSE z%=P%:=opt%
DEFFNendif:IFz%=-1:=opt% ELSE z%=P%-z%:P%=P%-z%:O%=O%-z%:=opt%
DEFFNelse:IFz%=-1:z%=P%:=opt% ELSE z%=P%-z%:P%=P%-z%:O%=O%-z%:z%=-1:=opt%
:
name$="AP1"
DIM mcode% &1000,L% -1:load%=&8000
OS_CLI=&FFF7:OSBYTE=&FFF4:OSWORD=&FFF1:OSWRCH=&FFEE
OSWRCR=&FFEC:OSNEWL=&FFE7:OSASCI=&FFE3:OSRDCH=&FFE0
OSFILE=&FFDD:OSARGS=&FFDA:OSBGET=&FFD7:OSBPUT=&FFD4
OSGBPB=&FFD1:OSFIND=&FFCE:GSINIT=&FFC2:GSREAD=&FFC5
:
TARGET%=-1:REM Build for 6502Em with no FDC hardware, no real ADFS
TARGET%=5 :REM Build for Compact
TARGET%=0 :REM Build for Electron
:
:
REM v1.30 22-Jan-2016: Date of whole ROM build
REM       28-Feb-2016: Serial IRQ mask ignores IRQs if no 6281 present
REM       01-Mar-2016: Fixed wrong destination in serial-absence test
REM                    IRQ handler checks ignore-all before RxRDY/TxRDY
:
verROM$="1.31" :dateROM$="22 Jun 2018":REM Date of whole ROM build
ver$   ="1.31" :date$   ="22 Jun 2018":REM Date of AP1 Support
REM 28-Jun-2018: Ensures LANG only used b7-b6,b3-b0 of L0D6D
:
verROM$="1.33" :dateROM$="22 May 2020":REM Date of whole ROM build
ver$   ="1.31" :date$   ="22 Jun 2018":REM Date of AP1 Support
:
verROM$="1.33" :dateROM$="22 Jun 2018":REM Date of whole ROM build
ver$   ="1.311":date$   ="22 Jun 2018":REM Date of AP1 Support
REM 28-Dec-2020: Claims BRKV on startup to catch startup errors
REM              Removed pre-v1.311 code
:
:
REM Base addresses
REM --------------
IF TARGET%<1 :ROMtable=&2A0:REM Electron
IF TARGET%>0 :ROMtable=&2A1:REM BBC, Master
:
:
REM Workspace
REM ---------
L0D70=&0D70  :REM Saved file vectors
L0D6C=&0D6C  :REM Saved ROM semaphore when disabled
L0D6D=&0D6D  :REM Default language ROM
:
:
REM Saved file vectors
REM ------------------
L0D70=L0D70+&0:L0D72=L0D70+&2:L0D74=L0D70+&4:L0D76=L0D70+&6
L0D78=L0D70+&8:L0D7A=L0D70+&A:L0D7C=L0D70+&C
:
:
REM Workspace
REM ---------
REM &0D68-&0D6C Plus 1 Support
REM &0D6D-&0D6F ROM Manager Support
REM &0D70-&0D7F ROM/TAPE intercept
REM
REM &0D68 flags
REM  &Fx = 100Hz poll enabled
REM  &80 = Plus 1 100Hz handlers disabled
REM  &40 = printer buffer active
REM  &20 = ADC active
REM  &10 = serial active
REM  &08 = temporarily disabled for TAPE/ROM access
REM  &04 = ROM table has been moved during Reset
REM  &02 = ignore serial interupts
REM  &01 = Plus 1 disabled
REM &0D69 Serial speed control register (&FC61) RAM copy
REM &0D6A Serial interupt mask (&FC65)
REM  &80 = input port change (incoming RTS)
REM  &01 = serial output buffer active
REM  &02 = serial input buffer active
REM &0D6B ROMSTROBE (&FC73) RAM copy
REM &0D6C Saved ROM paging semaphore when temporarily disabled
REM &0D6D If b7=0 - default language ROM in b3-b0
REM       If b6=1 - reserved for NoRelocate
REM       If b5=1 - Tube disabled
REM       If b4=1 - spare
REM       b3-b0   - language ROM
REM &0D6E INSERT/UNPLUG bitmap 0-7, b7=7, 0=inserted, 1=unplugged
REM &0D6F INSERT/UNPLUG bitmap 8-15, b7=15, 0=inserted, 1=unplugged
REM
REM &0D70 Old FILEV when TAPE/ROM selected
REM &0D72 Old ARGSV when TAPE/ROM selected
REM &0D74 Old BGETV when TAPE/ROM selected
REM &0D76 Old BPUTV when TAPE/ROM selected
REM &0D78 Old GBPBV when TAPE/ROM selected
REM &0D7A Old FINDV when TAPE/ROM selected
REM &0D7C Old FSCV  when TAPE/ROM selected
REM &0D7E (no longer used)
REM
REM &0DF0,X b7=disabled, b6-b0=unused
:
REM I/O addresses
REM -------------
REM &FC60-6F  Electron 2681 serial controller
REM  &FC60 Control
REM  &FC61 Serial speed control register
REM         b7-b4=tranmit, b3-b0-receive
REM  &FC62 Serial command register
REM  &FC63 Transmit/Receive Data Register
REM  &FC64 Aux Control/Input Changed
REM  &FC65 Serial interupt mask - RAM copy in &0D6A
REM  &FC6D Output config/Input port
REM   Read CTS in bit 2
REM  &FC6E Serial set output bits
REM   Write &01 to clear RTS
REM  &FC6F Serial clear output bits
REM   Write &01 to set RTS
REM
REM &FC70-73  Electron expansion
REM  &FC70 AtoD convertor
REM         Read: data value, Write: control
REM  &FC71 Centronics port
REM         Write: write to port
REM  &FC72 Electron expansion status
REM         Read: b7=BUSY, b6=ADC, b5=Fire1, b4=Fire2
REM  &FC73 Electron
REM         Write: ROMSTROBE
REM
REM &FCC0-08 Floppy disk controller
REM  &FCC0 Drive select register
REM  &FCC4 FDC command/status
REM  &FCC7 FDC data
REM
REM &FCD8/&FCD9 lock/unlock register bank 5/6
REM &FCDA/&FCDB lock/unlock register bank 13/15
REM &FCDC/&FCDD lock/unlock register bank 0/2
REM &FCDE/&FCDF lock/unlock register bank 1/3
REM
REM &FCFC AQR paging register
REM &FCFD unlock AQR
REM &FCFE lock AQR
:
:
file$=name$+"v"+LEFT$(ver$,1)+MID$(ver$,3,2)
FOR P=0 TO 1:opt%=P*2+4
P%=load%:O%=mcode%
[OPT opt%
.exec%
.L8000:JMP L8021                         :\ Language entry
.L8003:JMP PlusOne                       :\ Service entry
.L8006:EQUB &C0                          :\ ROM type=Serv+Lang+6502 BASIC
.L8007:EQUB L8019-L8000-1                :\ Copyright offset
.L8008:EQUB EVAL("&"+MID$(verROM$,3,2))  :\ ROM version byte
.L8009
OPT FNif(TARGET%<>0)
EQUS MID$("6502EmBBC B+MasterCompact",((TARGET%+1)AND-2)*3+1,6+3*(TARGET%=1)-(TARGET%=5))+" "
OPT FNendif
\EQUS "RH Plus 1/AP6":\EQUB 0            :\ ROM title
EQUS "RH Plus 1":EQUB 0                  :\ ROM title
EQUS LEFT$(verROM$,4)+LEFT$(CHR$(96+VALRIGHT$(verROM$,1)),LENverROM$-4) :\ Version string
EQUS " ("+dateROM$+")":EQUB 0            :\ Version date
.L8019
EQUS "(C)J.G.Harston":EQUB 0             :\ Copyright string
.NULL
RTS

.PlusOne
JSR NULL:JMP L8067
EQUB &82:EQUB PlusCopy-PlusOne-1:EQUB EVAL("&"+MID$(ver$,3,2))
EQUS "Plus 1 Support":EQUB 0
EQUS LEFT$(ver$,4)+" ("+date$+")":EQUB 0 :\ Version string
.PlusCopy
EQUS "(C)JGH & Acorn":EQUB 0


\ LANGUAGE HANDLER
\ ================
\ Languages higher than me are disabled, so I am entered by default.
\ Restore ROM table then try to enter default language. If no default look
\ for a default language lower than me, then above me.
\ Results in my ROM name being displayed then new default ROM name displayed.
\
.L8021
LDA #&A3:LDX #&80        :\ OSBYTE &A3,&80,&04
LDY #&04:JSR OSBYTE      :\ Restore ROM table, find default language
.L803B
TXA:BMI Prompt           :\ No language, or entering me as a language
LDA #142:JMP OSBYTE      :\ Enter as a language
:
\ No-Language Environment
\ -----------------------
.Report
JSR OSNEWL:LDY #1
.ReportLp
LDA (&FD),Y:BEQ ReportDone
JSR OSWRCH:INY:BNE ReportLp
.ReportDone
JSR OSNEWL
.Prompt
LDX #&FF:TXS:CLI
JSR ClaimBRKV
LDA #ASC"*":JSR OSWRCH
LDX #Osword0 AND 255
LDY #Osword0 DIV 256
LDA #0:JSR OSWORD:BCS PromptEsc
LDX #0:LDY #7:JSR OS_CLI
JMP Prompt
.PromptEsc
LDA #126:JSR OSBYTE
BRK:EQUB 17:EQUS "Escape":BRK
.Osword0
EQUW &0700:EQUB 255:EQUB 32:EQUB 255

.Serv10
LDA &203:CMP #&C0
PLA:BCC ClaimBRKexit   :\ Only claim if MOS has BRKV
.ClaimBRKV
LDX #&03:STX &202
LDX #&FF:STX &203
LDX #Report AND 255:STX &DA2
LDX #Report DIV 256:STX &DA3
LDX &F4:STX &DA4
.ClaimBRKexit
RTS


\ SERVICE HANDLER
\ ===============
.L8067
PHA
LDA &0DF0,X:BMI L80CD:\ If b7=1, disabled, ignore service call


\ Dispatch service call
\ ---------------------
.L808E
PLA:PHA:TAX          :\ Get service call back
CPX #&16:BCS L80CC   :\ Unsupported, exit
ASL A:TAX            :\ Index into dispatch table
LDA L80A0+1,X:PHA    :\ Stack high byte of address
LDA L80A0+0,X:PHA    :\ Stack low byte of address
RTS                  :\ Return to jump to routine

\ Service call dispatch table
\ ---------------------------
.L80A0
EQUW L80CC-1 :\ &00 - Null
EQUW L815E-1 :\ &01 - Private workspace
EQUW L80CC-1 :\ &02 - Null
EQUW L80CC-1 :\ &03 - Null
EQUW L80CC-1 :\ &04 - Null
EQUW L81A6-1 :\ &05 - Interupt
EQUW L8617-1 :\ &06 - Error
EQUW L83BA-1 :\ &07 - OSBYTE
EQUW L80CC-1 :\ &08 - Null
EQUW L80CC-1 :\ &09 - Null
EQUW L80CC-1 :\ &0A - Null
EQUW L80CC-1 :\ &0B - Null
EQUW L80CC-1 :\ &0C - Null
EQUW L80CC-1 :\ &0D - Null
EQUW L80CC-1 :\ &0E - Null
EQUW L8690-1 :\ &0F - Vectors changed
EQUW Serv10-1:\ &10 - Close Spool/Exec
EQUW L80CC-1 :\ &11 - Null
EQUW L80CC-1 :\ &12 - Null
EQUW L8258-1 :\ &13 - Character in serial buffer
EQUW L8261-1 :\ &14 - Character in printer buffer
EQUW L8232-1 :\ &15 - 100Hz poll

.L80CC:LDX &F4          :\ Restore registers and return
.L80CD:PLA:RTS          :\ Restore A and return
.L80D0:STA &F0          :\ Pass A to returned X
.L80D1:LDX &F4          :\ Restore ROM to X
PLA:LDA #&00:RTS        :\ Claim call and return


\ SERVICE 1 - Shared workspace
\ ============================
\ Set up Plus 1 support
.L815E
TYA:PHA                    :\ Save workspace pointer
OPT FNif(TARGET%<1)
  LDA &FFB2
  CMP #&40:BEQ L8160       :\ Running on Electron?
  LDX &F4:LDA &0DF0,X
  ORA #&80:STA &0DF0,X     :\ Not Electron, disable myself
  .L8160
OPT FNendif
LDA #0:STA &0D68           :\ No 100Hz calls enabled, ROM table not moved, nothing disabled
STA &0D6B:STA &FC73        :\ Set ROMSTROBE and copy to &00
OPT FNif(TARGET%<1)
  LDA &28D                 :\ Check Break type
OPT FNendif
BEQ L8182                  :\ Soft Break (or not Electron), don't move ROM table
LDX &F4:BPL L816E          :\ Jump to start at the ROM above me
.L8163
LDA ROMtable,X:STA &0380,X :\ Copy ROM table to &0380-&038F
AND #&BF:STA ROMtable,X    :\ Remove language bit from ROM byte
.L816E
INX:CPX #&10:BCC L8163
LDA #4:STA &0D68           :\ Set 'ROM table moved'
.L8182
LDX #&04:JSR L8388         :\ Set maximum ADC channel to 4
LDA &028D:CLC:BEQ L8192    :\ Soft Break, don't set defaults
.L818C
OPT FNif(FALSE)
  LDA &28F:AND #&CF:STA &28F :\ Reset disk access speed
OPT FNendif
LDX #&01:STX &285          :\ Set Printer Type to 1 (parallel)
SEC                        :\ SEC=use default serial speed
.L8192
JSR L8567                  :\ Initialise serial interface
PLA:TAY:JMP L80CC


\ SERVICE 5 - Interrupt
\ =====================
.L81A6
LDA #&02
BIT &0D68:BNE L81BB     :\ If IRQ Ignore, exit
LDA &0D6A:BPL L81BB     :\ Serial Mask b7=0, ignore all IRQs
AND &FC65:BMI L81BE     :\ Mask with 6281 IRQ, b7=input port changed (RTS)
LSR A:BCS L81CB         :\ b0 set -> TxRDY
LSR A:BCS L8206         :\ b1 set -> RxRDY
.L81BB
JMP L80CC               :\ Restore all and return unclaimed

.L81BE
LDA #&04                :\ Test bit 2
BIT &FC64:BNE L81C8     :\ Input bit 2 not changes
JSR L85AA               :\ 
.L81C8
JMP L80D1               :\ Claim call and return

.L81CB
LDA #&04                :\ Test CTS in bit 2
BIT &FC6D:BNE L8200     :\ Not CTS, skip to set serial inactive
JSR L85CD               :\ Get byte from SerOut buffer
BCC L81EA               :\ If not empty, write it to SerTx
LDX &0285               :\ Get Printer Type
CPX #&02:BNE L81F2      :\ Not 2=Serial
JSR L85D3               :\ Get byte from Printer Buffer
PHA:PHP
JSR L87AB               :\ Set/Clear printer Buffer Busy flag
PLP:PLA
BCS L81F2               :\ Printer Buffer was empty, skip past
.L81EA
STA &FC63               :\ Write byte to DataTx
LDX #&00:JMP L81FA      :\ Set SerialFlag to 0 and return

.L81F2
JSR L85B9           :\ Set serial inactive
JSR L82EB           :\ Set/Clear CTS from buffer space
LDX #&FF            :\ Set SerialFlag to &FF and return
.L81FA
STX &024F           :\ Serial Use Flag
JMP L80D1           :\ Claim call and return

.L8200
JSR L85B9           :\ Set serial inactive
JMP L80D1           :\ Claim call and return

.L8206
LDX &FC63           :\ Read from 2681 Data Register
LDA &FC61           :\ Read from 2681 Status Register
AND #&F0:BNE L8221  :\ If any error bit set, skip to generate event
TXA:JSR L85C8       :\ Insert into serial input buffer
JSR L85D9:BCS L821E :\ At least 8 bytes left, exit
LDA #&01:STA &FC6F  :\ Raise RTS to stop other end sending
.L821E
JMP L80D1           :\ Claim and return

.L8221
TXA:PHA             :\ Save byte read
LDX &FC61           :\ Read from 2681 Status again
JSR L85A0           :\ Reset 6281 Error Status
PLA                 :\ Get byte back
LDY #&07:JSR &FFBF  :\ Generate Event 7 - Serial Error
JMP L80D1           :\ Claim and return


\ SERVICE &15 - 100Hz Poll
\ ========================
.L8232
DEY:TYA:PHA         :\ Decrement semaphore
LDA #&40:BIT &0D68  :\ Check printer buffer active
BEQ L823F:JSR L827D :\ If active, try to send character to printer
.L823F
LDA #&20:BIT &0D68  :\ Check if ADC active
BEQ L8249:JSR L82A1 :\ If active, check for ADC conversion
.L8249
LDA #&10:BIT &0D68  :\ Check if serial active
BEQ L8253:JSR L82EB
.L8253
PLA:TAY             :\ Restore semaphore
JMP L80CC           :\ Return unclaimed

\ Character entering serial output buffer
\ =======================================
.L8258
JSR L85AA           :\ Write something to serial port
JSR L82F2           :\ Set/Clear CTS if input buffer almost full
JMP L80D1           :\ Claim call and return

\ Character entering printer output buffer
\ ========================================
.L8261
TYA:PHA             :\ Preserve Y
JSR L826B           :\ Process output character
PLA:TAY:JMP L80D1   :\ Restore, claim call and return

.L826B
LDX &0285           :\ Get printer destination
CPX #&01:BEQ L827D  :\ Parallel printer
CPX #&02:BNE L827C  :\ Not serial printer

\ Output to serial printer
\ ------------------------
JSR L85AA           :\ Write something to serial port
JSR L82F2           :\ Set/Clear CTS if input buffer almost full
.L827C
RTS

\ Output to parallel printer
\ --------------------------
.L827D
BIT &FC72:BMI L829C :\ If printer busy, turn 100Hz poll on and return
JSR L85D3           :\ Get character from printer buffer
BCS L8293           :\ If buffer empty, turn off 100Hz poll
STA &FC71           :\ Send to printer port
LDA #&40:JSR L85EA  :\ Set b6 of &0D68, turn on 100Hz poll
CLC:JMP L8299       :\ Clear Printer Buffer Busy flag and return

\ Printer buffer empty
\ --------------------
.L8293
LDA #&40:JSR L85FD  :\ Clear b6 of &0D68, turn off 100Hz poll
SEC                 :\ Set b7 of &02C6 and return
                    :\ Set Serial Error event flag
.L8299
JMP L87AB           :\ Set/Clear Printer Buffer Busy flag

\ Printer busy
\ ------------
.L829C
LDA #&40:JMP L85EA  :\ Set b6 of &0D68, turn on 100Hz poll


\ Check for ADC conversion
\ ========================
.L82A1
BIT &FC72:BVS L82FC   :\ If no ADC ready, return
LDX &024C             :\ Get current ADC channel
TXA:BEQ L82FC         :\ No ADC channel, return
LDA #&00:STA &02F7,X  :\ Set low byte to zero
LDA &FC70:STA &02FB,X :\ Set high byte from ADC
STX &02F7             :\ Store as last channel converted
LDY #&03:JSR &FFBF    :\ Event 3 - ADC complete
LDX &02F7             :\ Get last channel converted
DEX                   :\ Step down to next channel
BNE L82D0             :\ If nonzero, start this channel
LDX &024D             :\ Get maximum ADC channel
TXA:BNE L82D0         :\ If nonzero, start this channel
LDA #&20:JMP L85FD    :\ Clear b5 of &0D68, turn off 100Hz poll
.L82D0
.L82D3
CPX #&05:BCC L82D9    :\ If channel<5, use it
LDX #&04              :\ Channel>4, force to channel 4
.L82D9
TXA:STX &024C         :\ Store as current channel
TAX:BEQ L82E6         :\ If channel zero, exit
LDA L82E7-1,X         :\ Get control value for this channel
STA &FC70             :\ Write to ADC control
.L82E6
RTS

\ ADC control values
\ ------------------
.L82E7
EQUB &04:EQUB &05
EQUB &06:EQUB &07

\ Set CTS according to input buffer state
\ ---------------------------------------
.L82EB
LDA &0D6A
AND #&02:BEQ L82F7  :\ Serial input buffer inactive, raise CTS

\ Set/Clear CTS if serial input buffer nearly full
\ ------------------------------------------------
.L82F2
JSR L85D9           :\ Count space in serial input buffer
BCS L82FD           :\ Still space left in input buffer
.L82F7
LDA #&01:STA &FC6F  :\ Raise RTS to pause sender
.L82FC
RTS

.L82FD
LDA #&01:STA &FC6E  :\ Lower RTS to unpause sender
RTS

\ OSBYTE &A3 - Application call
\ =============================
.L8303
LDA &F0
CMP #&80:BNE L8319     :\ Not reason &80, exit
LDX &F1:CPX #4
BEQ L831C              :\ Subcall &04 - restore ROM table
BCS L8319              :\ Subcall >&04 - exit
TXA:ROR A              :\ Cy=b0 of subcall, enable/disable flag
LDA &0D68:PHA          :\ Save old setting
BCC AppEnable          :\ b0=0, enable setting
ORA AppMask,X          :\ Set a bit in flags
BCS AppReturn
.AppEnable
AND AppMask,X:INX      :\ Clear bit in flags, point to set bit
.AppReturn
STA &0D68              :\ Store new setting
PLA:AND AppMask,X:PHA  :\ Get old setting
TXA:EOR #1:BNE AppDone :\ Subcall 2,3 just return
BCS AppDisable         :\ Subcall 1, disable Plus 1 functions
JSR L8671              :\ Enable Plus 1 functions
JMP AppDone
.AppDisable
JSR L8641              :\ Disable Plus 1 functions
.AppDone
PLA:JMP L80D0          :\ Jump to return old flags
.AppMask
EQUB &FE:EQUB &01
EQUB &FD:EQUB &02
.L8319
JMP L80CC

\ OSBYTE &A3,&80,4 - Restore ROM table
\ ------------------------------------
.L831C
LDA &0D68                  :\ Check system flags
AND #4:BEQ L832A           :\ ROM table not moved
LDX &F4:BPL L8325          :\ Start at the ROM above me
.L831F
LDA &0380,X:STA ROMtable,X :\ Copy &0380-&038F back to ROM table
.L8325
INX:CPX #&10:BCC L831F
LDA &0D68:AND #&FB:STA &0D68 :\ Set 'ROM table not moved'
.L832A
LDY #1                       :\ On first pass, start at Plus 1 ROM
LDA L0D6D:AND #&8F           :\ Get default LANG ROM number
TAX:BPL TryThisROM           :\ b7=0, default ROM
.LookForROMlp
DEY:BNE P%+4:LDX &F4         :\ Start at Plus 1 ROM
DEX:BPL P%+4:LDX #15         :\ Step down, looping around
CPX &F4:BEQ NoLanguage       :\ If looped back to Plus 1, no more left
.TryThisROM
LDA ROMtable,X               :\ Get ROM byte
ASL A:BPL LookForROMlp       :\ No language, try next one down
.NoLanguage
TXA
CMP &F4:BNE P%+4:ORA #&80    :\ If no language found, return &80+Plus1
JMP L80D0                    :\ Jump to return A as returned X


\ OSBYTE &80 - ADVAL
\ ==================
\ ADVAL 1-4 are performed by MOS
.L8366
LDA &F0:BNE L8319   :\ Not ADVAL(0), exit
LDA &FC72:PHA       :\ Read Plus 1 status
BPL L8373:JSR L826B :\ If printer not busy, try to send a character
.L8373
PLA:LSR A:LSR A     :\ Move fire buttons into b0-b1
LSR A:LSR A
AND #&03:EOR #&03   :\ Keep and toggle b0-b1
JMP L80D0           :\ Return fire buttons


\ OSBYTE &10 - Maximum ADC channel
\ ================================
.L837F
LDX &F0:JSR L8388   :\ Set maximum ADC channel
JMP L80D0           :\ Return maximum actually set
.L8388
TXA:BEQ L8395       :\ Zero channels, set and return
JSR L82D3:TXA       :\ Check within range and initialise ADC
PHA
LDA #&20:JSR L85EA  :\ Enable 100Hz poll for ADC
PLA
.L8395
STA &024D:RTS       :\ Store maximum ADC channel

\ OSBYTE &11 - Start ADC conversion
\ =================================
.L839A
LDA #&00:STA &02F7     :\ Clear 'last channel'
LDX &F0:JSR L82D3:TXA  :\ Start conversion on channel X
PHA:LDA #&20:JSR L85EA :\ Enable 100Hz poll for ADC
PLA:JMP L80D0          :\ Return X=channel actually started


\ OSBYTE &6E - Write to ROMSTROBE
\ ===============================
\ Writes X to ROMSTROBE at &FC73 and RAM copy at &0D6B
\ Returns old ROMSTROBE from RAM copy
\
.L83AC
LDX &F0             :\ Get new ROMSTROBE from X parameter
LDA &0D6B           :\ Get old ROMSTROBE
STX &0D6B:STX &FC73 :\ Store new ROMSTROBE and output it
JMP L80D0           :\ Return old ROMSTROBE as X


\ SERVICE 7 - OSBYTE
\ ==================
.L83BA
LDA &EF             :\ Get OSBYTE number
CMP #&80:BEQ L8366  :\  &80   - ADVAL
CMP #&10:BEQ L837F  :\ *FX16  - Maximum ADC channel
CMP #&11:BEQ L839A  :\ *FX17  - Start ADC conversion
CMP #&07:BEQ L83E6  :\ *FX7   - serial receive speed
CMP #&08:BEQ L83EC  :\ *FX8   - serial transmit speed
CMP #&9C:BEQ L8436  :\  &9C   - serial control
CMP #&02:BEQ L840F  :\ *FX2   - input stream
CMP #&6E:BEQ L83AC  :\ *FX110 - write to ROMSTROBE
CMP #&A3:BNE L83E3
JMP L8303           :\  &A3   - application call
.L83E3
JMP L80CC

\ OSBYTE 7 and 8 - set serial speed
\ =================================
\ On entry, X=baud rate setting (0=default)
\ On exit   X=control register setting that wasn't changed

\ OSBYTE &07 - Serial receive speed
\ ----------------------------------
.L83E6
LDA #&F0:STA &F1    :\ Set &F1 to &F0 for 'receive'
BNE L83F0

\ OSBYTE &08 - Serial transmit speed
\ ----------------------------------
.L83EC
LDA #&0F:STA &F1    :\ Set &F1 to &0F for 'transmit'

\ Set serial speed, &F1=control mask
\ ----------------------------------
.L83F0
LDX &F0             :\ Get OSBYTE X value
CPX #&0C:BCS L840C  :\ If speed>11, exit unchanged
LDA &F1:EOR #&FF    :\ Get mask and toggle it
AND &0D69           :\ Mask with current baud register copy
STA &F0             :\ Keep the bits we aren't going to change
LDA L84B2,X         :\ Translate X to baud rate control value
AND &F1             :\ Mask to keep the half we are going to change
ORA &F0             :\ Merge with current setting
STA &0D69           :\ Update the baud register RAM copy
STA &FC61           :\ Store in baud register
.L840C
JMP L80D1           :\ Claim call and return

\ OSBYTE &02 - select input stream
\ ================================
.L840F
LDA &F0:PHA         :\ Save OSBYTE X value, input source
AND #&01:TAX        :\ Keep bit 0, keyboard/serial select
STA &0241           :\ Store selected source
PLA:BEQ L8471       :\ Get original selection, exit if X=0, serial disabled
LDA #&01:STA &FC62  :\ Enable serial input
LDA &0D6A:ORA #&02  :\ Enable receive interupts
STA &0D6A:STA &FC65 :\ Write to IRQ mask and 6281 IRQ register
JSR L82EB           :\ Set/Clear CTS
LDA #&10:JSR L85EA  :\ Increment ROM polling register if needed
JMP L80D1           :\ Claim call and return

\ OSBYTE &9C - serial control
\ ===========================
\ On entry, Y=action, X=parameters, in 6850 format
.L8436
LDA #&E3            :\ *FX156,x,227 to set word format
CMP &F1:BNE L8492   :\ Not Y=227

\ Y=227, set serial word format
\ -----------------------------
BIT &F0:BNE L846E   :\ X must be %000xxx00
LDA &F0             :\ Get X parameter
LSR A:LSR A:NOP:TAX :\ Move up two bits
JSR L85A4           :\ Select control register &10
LDA &FC60           :\ Read from control register &10
AND #&E0:STA &F1    :\ Save temporarily

\ Manipulate stuff to set serial word size
JSR L85A4           :\ Select control register &10
LDA L84BE,X         :\ 
AND #&1F            :\ 
ORA &F1             :\ 
STA &FC60           :\ Write to control register
LDA &FC60           :\ Read from control register
AND #&F0            :\ Keep b7-b4
LDY L84BE,X
BMI L8469           :\ If b7 set, skip
ORA #&0F            :\ If b7 clear, set b3-b0
.L8469
ORA #&07            :\ Set to %xxxxx111
STA &FC60           :\ Write to control register
.L846E
JMP L80D1           :\ Claim call and return

\ Turn off serial input
\ ---------------------
.L8471
LDA #&02:STA &FC62  :\ Disable receiver
JSR L8598           :\ Reset reciever
JSR L85A0           :\ Reset error status
LDA &0D6A:AND #&FD  :\ Reset serial input IRQ
STA &0D6A:STA &FC65 :\ Write to IRQ mask and serial port IRQ register
JSR L82EB           :\ Set/Clear CTS
LDA #&10:JSR L85FD  :\ Clear b4 of flags, turn off polling
JMP L80D1           :\ Claim call and return

.L8492
LDA #&9F            :\ *FX156,x,159 for a serial break
CMP &F1:BNE L846E   :\ Not Y=159, exit

\ Y=159, start/stop a serial break
\ --------------------------------
BIT &F0:BNE L846E   :\ X must be %0xx00000
LDA &F0             :\ Get X parameter
CMP #&60:BEQ L84AA  :\ *FX156,96,159 - start a break
LDA #&70:STA &FC62  :\ Else, stop transmitting a break
JMP L846E           :\ Claim call and return

.L84AA
LDA #&64:STA &FC62  :\ Start transmitting a break
JMP L846E           :\ Claim call and return

\ Baud rate look-up table
\ -----------------------
.L84B2
EQUB &BB:EQUB &00:EQUB &33  :\ 0=9600, 1=75,   2=150
EQUB &44:EQUB &66:EQUB &88  :\ 3=300,  4=1200, 5=2400
EQUB &99:EQUB &BB:EQUB &CC  :\ 6=4800, 7=9600, 8=19200
EQUB &11:EQUB &55:EQUB &AA  :\ 9=110,  10=600, 11=1800

\ Serial control look-up table
\ ----------------------------
.L84BE
EQUB &02:EQUB &06:EQUB &82:EQUB &86
EQUB &13:EQUB &93:EQUB &83:EQUB &87

\ Initialise serial interface
\ ---------------------------
\ CC=use current settings, CS=use default settings
.L8567
LDA #0:STA &0D6A      :\ DMB, ignore serial interupts
JSR L85A4             :\ Reset MC6281 MR pointer
LDA #&93:STA &FC60    :\ First write, RTS=enabled, NoParity, 8bit
LDA #&07:STA &FC60    :\ Second write, StopBit=1 bit length
EOR &FC60:BNE L8597   :\ DMB, read back, if hardware absent, exit
LDA #&8F:STA &FC64    :\ Set AuxControl to Baud Rate 2, IRQs on
LDA &0D69:BCC L8580   :\ Get current baud setting
LDA #&BB              :\ Default baud rate=9600
.L8580
STA &0D69:STA &FC61   :\ Set baud register and RAM copy
JSR L8598             :\ Reset 6821 receiver
JSR L859C             :\ Reset 6821 transmitter
JSR L85A0             :\ Reset 6821 error status
LDA #&80:STA &0D6A    :\ Set IRQ mask to allow serial interupts
STA &FC65             :\ Enable 6821 interupts
.L8597
RTS

.L8598
LDA #&20:BNE L85A6  :\ &20=Reset Receiver
.L859C
LDA #&30:BNE L85A6  :\ &30=Reset Transmitter
.L85A0
LDA #&40:BNE L85A6  :\ &40=Reset Error Status
.L85A4
LDA #&10            :\ &10=Reset MR pointer
.L85A6
STA &FC62:RTS       :\ Write to command register

.L85AA
LDA &0D6A:ORA #&01  :\ Set serial buffer active
STA &0D6A:STA &FC65 :\ Write to IRQ mask and serial port IRQ register
LDA #&04:BNE L85A6  :\ Write &04=Transmitter Enabled to command register

.L85B9
LDA &0D6A:AND #&FE  :\ Set serial buffer inactive
STA &0D6A:STA &FC65 :\ Write to IRQ mask and serial port IRQ register
LDA #&08:BNE L85A6  :\ Write &08=Transmitter Disabled to command register

.L85C8
LDX #&01            :\ X=1 - serial input buffer
JMP (&022A)         :\ Jump to INSV

.L85CD
CLV                 :\ CLV=remove character
LDX #&02            :\ X=2 - serial output buffer
JMP (&022C)         :\ Jump to REMV

.L85D3
CLV                 :\ CLV=remove character
LDX #&03            :\ X=3 - printer buffer
JMP (&022C)         :\ Jump to REMV

\ Count space left in serial input buffer
\ ---------------------------------------
\ Returns CS=more than 8 bytes left
\         CC=less than 8 bytes left
.L85D9
JSR L85E3           :\ Count space in serial input buffer
CPY #&01:BCS L85E2  :\ If >&00FF, return CS
CPX #&09            :\ If >&0008, return CS
.L85E2
RTS

.L85E3
SEC                 :\ SEC=count space left
CLV                 :\ CLV=count buffer
LDX #&01            :\ X=1 - serial input buffer
JMP (&022E)         :\ Jump to CNPV

.L85EA
ORA &0D68           :\ Merge into current flags
LDX &0D68           :\ Get old value of flags to X
STA &0D68           :\ Store updated flags
TXA                 :\ Get old flags into A
AND #&F0:BNE L85E2  :\ If old flags had polling enabled, exit
:                   :\ We've changed to needing polling, increment semaphore
.L85F8
LDA #&16:JMP OSBYTE :\ Inc. ROM polling semaphore

.L85FD
TAX                 :\ Save mask in X
LDA #&F0:BIT &0D68  :\ Check current polling flags
BEQ L85E2           :\ No flags have polling enabled, exit
TXA:EOR #&FF        :\ Get mask back and toggle it
AND &0D68:STA &0D68 :\ Remove the bit and update flags
AND #&F0:BNE L85E2  :\ If any polling enabled, exit
:                   :\ Nothing left needing polling, decrement semaphor
.L8612
LDA #&17:JMP OSBYTE :\ Dec. ROM polling semaphore


\ SERVICE 6 - Error
\ =================
.L8617
LDA #&08:BIT &0D68:BEQ L8622  :\ Not temporarily disabled, skip
LDA L0D6C:STA &0249           :\ Restore ROM paging semaphore
.L8622
LDA #&01:BIT &0D68:BNE L863E  :\ Plus 1 disabled, ignore error
LDA &EF:PHA
LDA &F0:PHA:LDA &F1:PHA       :\ Save OSBYTE/OSWORD parameters
JSR L8671
PLA:STA &F1:PLA:STA &F0
PLA:STA &EF
.L863E
JMP L80CC                     :\ Restore and return unclaimed


\ Disable Plus 1 functions
\ ========================
.L8641
PHA:TXA:PHA:TYA:PHA
LDA &0D68:BMI L865C :\ Bit 7 set, already disabled
PHA
ORA #&80:STA &0D68  :\ Set bit 7 of flags
PLA:BEQ L865C       :\ No handlers to disable
JSR L8612           :\ Decrement ROM polling semaphore
LDA #&01:STA &FC6F  :\ Raise 'RTS', stop serial sender
.L865C
PLA:TAY:PLA:TAX:PLA
RTS


\ Enable Plus 1 functions
\ =======================
\ Called after calling filing vector, so all four registers need to be saved
.L8662
PHP:PHA
LDA L0D6C:STA &0249 :\ Restore ROM paging semaphore
LDA &0D68:AND #&F7
STA &0D68           :\ Clear 'disabled' flag
PLA:PLP
.L8671
PHP:PHA:TXA:PHA:TYA:PHA
LDA &0D68:BPL L8689 :\ Bit 7 clear, already enabled
AND #&7F:STA &0D68  :\ Clear bit 7 of flags
BEQ L8689           :\ No handlers to enable
JSR L85F8           :\ Increment ROM polling semaphore
JSR L82EB           :\ Restore CTS state
.L8689
PLA:TAY:PLA:TAX:PLA:PLP
RTS


\ SERVICE &0F - Vectors changed
\ =============================
.L8690
LDX &0213:INX:BEQ L86A3   :\ FILEV not pointing to MOS, exit
LDA #&00:TAY:JSR OSARGS   :\ Read current filing system
CMP #&03:BCS L86A3        :\ Not TAPE/ROM, exit
CMP #&00:BNE L86B4
.L86A3
JMP L80CC

\ Filing system vectors
\ ---------------------
.L86A6
EQUW L8736 :\ FILEV
EQUW L875F :\ ARGSV
EQUW L8709 :\ BGETV
EQUW L8712 :\ BPUTV
EQUW L871F :\ GBPBV
EQUW L873F :\ FINDV
EQUW L874C :\ FSCV

\ Vectors changed, now using TAPE/ROM
\ -----------------------------------
.L86B4
PHP:SEI                      :\ Disable IRQs while changing vectors
LDY #&1B:LDX #&12
.X86D1
LDA &0200,X:STA L0D70-&12,X  :\ Copy filing system vectors
TYA:STA &0200,X              :\ to L0D70-L0D7D and redirect them
LDA &0201,X:STA L0D70-&11,X  :\ to extended vectors
LDA #&FF:STA &0201,X
LDA L86A6-&12,X:STA &0D9F,Y  :\ Claim extended filing system vectors
INX:INY
LDA L86A6-&12,X:STA &0D9F,Y
INX:INY
LDA &F4:STA &0D9F,Y
INY:CPX #&20:BNE X86D1
PLP
.L8706
JMP L80CC

\ Redirected BGETV
\ ----------------
.L8709
JSR L877E:JSR L879C:JMP L8662 :\ Disable Plus 1, call BGET, enable Plus 1

\ Redirected BPUTV
\ ----------------
.L8712
JSR L877E:JSR L879F:JMP L8662 :\ Disable Plus 1, call BPUT, enable Plus 1

\ Pass OSGBPB 5-7, 9+ on without disabling Plus 1
\ -----------------------------------------------
.L871B
PLP:JMP L87A2

\ Redirected GBPBV
\ ----------------
.L871F
PHP
CMP #&08:BEQ L872C  :\ Pass OSGBPB 8 on via veneer
CMP #&05:BCS L871B  :\ Pass OSGBPB 5-7, 9+ on directly
CMP #&01:BCC L871B  :\ Pass OSGBPB 0 on directly
.L872C
PLP
JSR L877E:JSR L87A2:JMP L8662 :\ Disable Plus 1, call GBPB, enable Plus 1

\ Redirected FILEV
\ ----------------
.L8736
JSR L877E:JSR L8796:JMP L8662 :\ Disable Plus 1, call FILE, enable Plus 1

\ Redirected FINDV
\ ----------------
.L873F
JSR L877E:JSR L87A5:JMP L8662 :\ Disable Plus 1, call FIND, enable Plus 1

\ Pass FSCV on without disabling Plus 1
\ -------------------------------------
.L8748
PLP:JMP L87A8

\ Redirected FSCV
\ ---------------
.L874C
PHP
CMP #&02:BCC L8748  :\ Pass <2 on without disabling
CMP #&06:BCS L8748  :\ Pass 6+ on without disabling
PLP                 :\ Pass 2-5 via veneer
JSR L877E:JSR L87A8:JMP L8662 :\ Disable Plus 1, call FSCV, enable Plus 1

\ Redirected ARGSV
\ ----------------
.L875F
PHP
CMP #&FF:BEQ L8774  :\ Ensure buffers - pass via veneer
CPY #&00:BEQ L8770  :\ Read filing info - pass on directly
CMP #&01:BEQ L8774  :\ PTR= - pass on via veneer
CMP #&03:BEQ L8774  :\ EXT= - pass on via veneer
.L8770
PLP:JMP L8799       :\ Pass on directly

.L8774
PLP
JSR L877E:JSR L8799:JMP L8662 :\ Disable Plus 1, call ARGSV, enable Plus 1


\ Temporarily disable Plus 1
\ ==========================
.L877E
PHP:PHA
JSR L8641           :\ Disable Plus 1
LDA &0249:STA L0D6C :\ Save ROM semaphore
LDA #&00:STA &0249  :\ Clear ROM semaphore
LDA &0D68:ORA #&08
STA &0D68           :\ Set 'disabled' flag
PLA:PLP:RTS

.L8796:JMP (L0D70)  :\ Old FILEV
.L8799:JMP (L0D72)  :\ Old ARGSV
.L879C:JMP (L0D74)  :\ Old BGETV
.L879F:JMP (L0D76)  :\ Old BPUTV
.L87A2:JMP (L0D78)  :\ Old GBPBV
.L87A5:JMP (L0D7A)  :\ Old FINDV
.L87A8:JMP (L0D7C)  :\ Old FSCV

\ Set/Clear buffer 3 busy flag
\ ----------------------------
.L87AB
ROR &02C6:RTS
:
]:IF O%>L%:P."Code overrun":END
NEXT
OSCLI"Save "+file$+" "+STR$~mcode%+" "+STR$~O%+" 0 FFFBBC00"
OSCLI"Stamp "+file$
ON ERROR ON ERROR OFF:END
*Quit