Newsgroups: comp.sys.cbm
From: rhialto@mbfys.kun.nl (Olaf Seibert)
Subject: PET RAM memory map
Organization: University of Nijmegen, The Netherlands
Date: Wed, 14 Dec 1994 19:22:02 GMT
This could be improved upon - not all locations have labels.
I must note I've never seen a PET memory map with labels, so in that
respect this is a first. I could add the locations for the Basic 1
ROMs in a next version. Corrections welcome. Enjoy.
; Commodore PET RAM Memory Map
; for Basic 2 and 4 (40 and 80 columns)
; V1.1 13 dec 1994
;
; Note that the labels in this list are matched up against C-64
; memory maps. All attempts were made to secure plausibility of
; placement.
; Locations marked with (64#..) are found by taking the label given
; for the C-64 and comparing ROM disassemblies. Many of these
; locations have RS-232 specific names.
LABEL HEX DECIMAL
ADDRESS LOCATION DESCRIPTION
USRPOK 0000 0 USR Function Jump Instr (4C)
USRADD 0001-0002 1-2 USR Address Low Byte / High Byte
CHARAC 0003 3 Search Character
ENDCHR 0004 4 Flag: Scan for Quote at End of String
COUNT 0005 5 Input Buffer Pointer / No. of Subscripts
DIMFLG 0006 6 Flag: Default Array DiMension / array name
initial / AND, OR flag
VAUYP 0007 7 Data Type: $FF = String, $00 = Numeric
INTFLG 0008 8 Data Type: $80 = Integer, $00 = Floating
GARBFL 0009 9 Flag: DATA scan/LlST quote/Garbage Coll
SUBFLG 000A 10 Flag: Subscript Ref / User Function Call
INPFLG 000B 11 Flag: $00 = INPUT, $40 = GET, $98 = READ
TANSGN 000C 12 Flag TAN sign / Comparison Result
000D 13 3: Flag to suppress PRINT or PRINT# when -ve
000E 14 3: File# of current I/O device (as 0010)
000F 15 3: terminal width (unused-carried over from TTY)
0010 16 3: width of source (unused - from TTY)
000D-000F 13-15 4: Disk Status DS$ descriptor
0010 16 4: File# of current I/O device (when non-zero
suppresses INPUT prompt etc)
LINNUM 0011-0012 17-18 Temp: Integer Value
TEMPPT 0013 18 Pointer Temporary String
LASTPT 0014-0015 19-21 Last Temp String Address
TEMPST 0016-001E 22-30 Stack for Temporary Strings
INDEX 001F-0022 31-34 Utility Pointer Area
RESHO 0023-0027 35-39 Floating-Point Product of Multiply
TXTTAB 0028-0029 40-41 Pointer: Start of BASIC Text
VARTAB 002A-002B 42-43 Pointer: Start of BASIC Variables
ARYTAB 002C-002D 44-45 Pointer: Start of BASIC Arrays
STREND 002E-002F 46-47 Pointer End of BASIC Arrays (+1)
FRETOP 0030-0031 48-49 Pointer: Bottom of String Storage
FRESPC 0032-0033 50-51 Utility String Pointer
MEMSIZ 0034-0035 52-53 Pointer: Highest Address Used by BASIC
CURLIN 0036-0037 54-55 Current BASIC Line Number
OLDLIN 0038-0039 56-67 Previous BASIC Line Number
OLDTXT 003A-003B 58-59 Pointer: BASIC Statement for CONT
DATLIN 003C-003D 60-61 Current DATA Line Number
DATPTR 003E-003F 62-63 Pointer: Current DATA Item Address
INPPTR 0040-0041 64-65 Vector: INPUT Routine
VARNAM 0042-0043 66-67 Current BASIC Variable Name
VARPNT 0044-0045 68-69 Pointer: Current BASIC Variable Data
FORPNT 0046-0047 70-71 Pointer: Index Variable for FOR/NEXT
0048-0049 72-73 Y-save; op-save; BASIC pointer save
004A 74 Comparison symbol accumulator: bits 0,1,2
are <, =, >.
004B-004C 75-76 Pointer to temp storage in RAM for FN DEF,
TAN, &c
004D-0050 77-80 Pointer to string, length and garbage
collect constant
TEMPF1 0054-0058 Temporary storage for FLPT value.
TEMPF2 0059-005D Temporary storage for FLPT value.
FACEXP 005E 94 Floating-Point Accumulator #1: Exponent
FACHO 005F-0062 95-98 Floating Accum. #1: Mantissa
FACSGN 0063 99 Floating Accum. #1: Sign
SGNFLG 0064 100 Pointer: Series Evaluation Constant Pointer
BITS 0065 101 Floating -accum. #1: Overflow Digit
ARGEXP 0066 102 Floating-Point Accumulator #2: Exponent
ARGHO 0067-006A 103-106 Floating Accum. #2: Mantissa
ARGSGN 006B 107 Floating Accum. #2: Sign
ARISGN 006C 108 Sign Comparison Result: Accum. # 1 vs #2
FACOV 006D 109 Floating Accum. #1. Low-Order (Rounding)
FBUFPT 006E-006F 110-111 Pointer: Cassette Buffer
CHRGET 0070-0087 112-135 Subroutine: Get Next Byte of BASIC Text
CHRGOT 0076 118 Entry to Get Same Byte of Text Again
TXTPTR 0077-0078 119-120 Pointer: Current Byte of BASIC Text
0070 INC $77
BNE $0076
0076 LDA $xxxx
CMP #$3A
BCS $0087
CMP #$20
BEQ $0070
SEC
SBC #$30
SEC
SBC #$D0
0087 RTS
RNDX 0088-008C 136-140 Floating RND Function Seed Value
TIME 008D-008F 141-143 Real-Time Jiffy Clock (approx) 1/60 Sec
CINV 0090-0091 144-145 Vector: Hardware Interrupt
CBINV 0092-0093 146-147 Vector: BRK Instr. Interrupt
NMINV 0094-0095 148-149 Vector: Non-Maskable Interrupt
STATUS 0096 150 Kernal I/O Status Word: ST
LSTX 0097 151 Current Key Pressed: 255 = No Key
SFDX 0098 Flag: Print Shifted Chars.
0099-009A Jiffy clock correction: 623rd 1/60 sec
does not increment time
STKEY 009B 155 Flag: STOP key / RVS key
SVXT 009C 156 Timing Constant for Tape
VERCK 009D 157 Flag: 0 = Load, 1 = Verify (Kernel)
NDX 009E 158 No. of Chars. in Keyboard Buffer (Queue)
RVS 009F 159 Flag: Print Reverse Chars. -1=Yes, 0=No Used
C3PO 00A0 160 Flag: Serial Bus-Output Char. Buffered
INDX 00A1 161 Pointer: End of Logical Line for INPUT
00A2 162 Not Used
LXSP 00A3-00A4 163-164 Cursor Y-X Pos. at Start of INPUT
BSOUR 00A5 165 Buffered Character for IEEE Bus
00A6 166 Key Image
BLNSW 00A7 167 Cursor Blink enable: 0 = Flash Cursor
BLNCT 00A8 168 Timer: Countdown to Toggle Cursor
GDBLN 00A9 169 Character Under Cursor
BLNON 00AA 170 Flag: Last Cursor Blink On/Off
?SYNO 00AB 171 Cassette Sync No. (64#0096)
?NXTBIT 00AB 171 Tape EOT Flag: EOT received from tape
CRSW 00AC 172 Flag: INPUT or GET from Keyboard
00AD 173 X save in tape handling (saves cassette #)
LDTND 00AE 174 No. of Open Files / Index to File Table
DFLTN 00AF 175 Default Input Device (0)
DFLTO 00B0 176 Default Output (CMD) Device (3)
PRTY 00B1 177 Tape Character Parity
DPSW 00B2 178 Flag: Tape Byte-Received
PSW=DPSW
00B3 179 Temporary save eg. logical address or DOS
wedge
00B7 183 Temp Data Area (64#00A3)
00B9 185 Temp Data Area (64#00A4)
BUFPNT 00BB Pointer: Tape I/O Buffer #1
00BC Pointer: Tape I/O Buffer #2
INBIT 00BD 189 Cassette Temp (64#00A7)
BITCI 00BE 190 Cassette Temp (64#00A8)
RINONE 00BF 191 RS-232 Flag: Check for Start Bit (64#00A9)
FNMIDX 00C0 192 Index to Cassette File name/Header ID for
Tape write.
PTR1 00C0 192 Tape Pass 1 Error Log
PTR2 00C1 193 Tape Pass 2 Error Log
RIDATA 00C2 194 Cassette Temp (64#00AA) read flags: 0=scan,
1-15=count, $40=load, $80=end of tape marker
RIPRTY 00C3 195 Cassette Short Cnt (64#00AB): counter of seconds
before tape write / checksum
PNT 00C4-00C5 196-197 Pointer: Current Screen Line Address
PNTR 00C6 198 Cursor Column on Current Line
SAL 00C7-00C8 199-200 Pointer: Tape Buffer/ Screen Scrolling
EAL 00C9-00CA 201-202 Tape End Addresses/End of Program
CMP0 00CB-00CC 203-204 Tape Timing Constants
QTSW 00CD 205 Flag: Editor in Quote Mode, $00 = NO
BITTS 00CE 206 Cassette Temp (64#00B4): Tape read timer flag
=IRQ enabled for Timer 1
00CF 207 End of tape read
00D0 208 Read character error
FNLEN 00D1 209 Length of Current File Name
LA 00D2 210 Current Logical File Number
SA 00D3 211 Current Secondary Address
FA 00D4 212 Current Device Number
LNMX 00D5 213 Physical Screen Line Length
00D5 213 4.80: right side of window
TAPE1 00D6-00D7 214-215 Pointer: Start of Tape Buffer
TBLX 00D8 216 Current Cursor Physical Line Number
DATAX 00D9 217 Current Character to Print
FNADR 00DA-00DB 218-219 Pointer: Current File Name
INSRT 00DC 220 Flag: Insert Mode, >0 = # INSTs
?ROPRTY 00DD 121 Cassette Temp
FSBLK 00DE 222 Cassette Read / Write Block Count
MYCH 00DF 223 Serial Word Buffer
LDTB1 00E0-00F8 224-248 3+4.40: Screen Line Link Table / Editor Temps
SCTOP 00E0 224 4.80: first line of window
SCBOT 00E1 225 4.80: last line of window
SCLF 00E2 226 4.80: first column of window
XMAX 00E3 227 4.80: Size of Keyboard Buffer
XMAX 03EB 1003 4.40
RPTFLG 00E4 228 4.80: Flag: REPEAT Key Used, $80 = Repeat
$40 = disable
RPTFLG 03EE 1006 4.40
KOUNT 00E5 651 4.80: Repeat Speed Counter
KOUNT 03EA 1002 4.40
DELAY 00E6 230 4.80: Repeat Delay Counter
DELAY 03E9 1001 4.40
00E7 231 4.80: Chime Time
03EC 1004 4.40: Chime Time
00E8 232 4.80: Home Count
00E9-00EA 233-234 4.80: input from screen vector (from E006)
00EB-00EC 235-236 4.80: print to screen vector (from E009)
00ED-00F7 237-247 4.80: not used
00F8 248 4.80: Counter to speed TI by 6/5
03ED 1005 4.40: Counter to speed TI by 6/5
CAS1 00F9 249 Tape Motor Interlock #1
CAS2 00FA 250 Tape Motor Interlock #2
STAL 00FB-00FC 251-252 I/O Start Address
MEMUSS 00FD-00FE 253-254 Tape Load Temps
00FF 255 Not used
0100-01FF 256-511 Micro-Processor System Stack Area
0100-010A 256-266 Floating to String Work Area
BAD 0100-013E 256-318 Tape Input Error Log
BUF 0200-0250 512-592 System INPUT Buffer
LAT 0251-025A 593-602 KERNAL Table: Active Logical File No's.
FAT 025B-0264 603-612 KERNAL Table: Device No. for Each File
SAT 0265-0270 613-623 KERNAL Table: Second Address Each File
KEYD 0270-027A 624-633 Keyboard Buffer Queue (FIFO)
TBUFFR 027A-0329 634-825 Tape I/O Buffer #1
027A Type of tape file:
1=program header for SAVE "",1,0
2=data block
3=absolute load SAVE "",1,1 (VIC-20 and later)
4=data file header
5=end of tape block: SAVE "",1,2
027B-027C Start address for load
027D-027E End address for load
027F-028E File name
TBUFFR 033A-03F9 826-1017 Tape I/O Buffer #2
033A 4: DOS byte parameter in RECORD / char ptr
033B 4: DOS drive 1 number
033C 4: DOS drive 2 number
033D 4: DOS length / write flag
033E 4: DOS 8-bit syntax checking flag
033F-0340 4: DOS diskette ID
0341 4: Length of DOS command string
0342-0352 4: Buffer for filename
0353-0380 4: Full DOS command string buffer
03EE-037F 4.80: Table of 80 bits to set TABs
DELAY 03E9 1001 4.40
KOUNT 03EA 1002 4.40
XMAX 03EB 1003 4.40
03EC 1004 4.40: Chime Time
03ED 1005 4.40: Counter to speed TI by 6/5
RPTFLG 03EE 1006 4.40
03F0-03F9 4.40: Table of 80 bits to set TABs
03FA-03FF 1018-1023 Unused
TIMOUT 03FC 1020 4: Flag: Kernal Variable for IEEE Timeout
0400-8000 1024-32767 Basic program area
0400 0 byte at start of Basic program
0401-0402 first link to next Basic line
0403-0404 first line number
0405- tokenized basic line, terminated with 00
followed by next link
8000-83E7 32768-33767 40 column screen memory
8000-87EF 32768-34767 80 column screen memory
A000-AFFF free space for 4K EPROM
B000-BFFF 3: free space for 4K EPROM
4 3
B000-DFFF C000-DFFF Basic keywords and operators, and general processing
E000-EFFF E000-EFFF Mostly screen editor functions
F000-FFFF F000-FFFF Kernel: tape processing, IEEE-488, jump table.
-Olaf.
--
___ Olaf 'Rhialto' Seibert rhialto@mbfys.kun.nl What's the use of
\X/ racism if you can't even see if a person belongs to your abhorred kind?
rom: rhialto@mbfys.kun.nl (Olaf Seibert)
Subject: PIA and VIA info (PET)
Organization: University of Nijmegen, The Netherlands
Date: Tue, 13 Dec 1994 11:13:11 GMT
PIA 6520 and VIA 6522
---------------------
Summarised by Olaf Seibert, from "Programming the PET/CBM" (by Raeto Collin
West) chapter 14 and The Transactor, Volume 4 Issue 05.
In the PET, you find the two PIAs at E810 and E820, and the VIA at E840.
The PIA
-------
The PIA has two 8-bit I/O ports, A and B, which are mostly identical in
function. All 8 bits can be set to input (1 in the DDR) or output (0 in
the DDR) independently. Bit 2 in CRx determines whether the DDRx or Px are
accessed. Each port has 2 control lines: CA1, CA2, CB1, CB2. The Cx1 are
input only, the Cx2 can be input or output.
PIAs have two interrupt lines: IRQA and IRQB. They may go low on a change
on the inputs of the Cxy lines. These interrupts may be enabled on either
an 1->0 or an 0->1 transition. The selected transition is called the
"active" transition. The flags which register that an active transition has
occurred are reset by reading the appropriate PORT register.
Register map:
E810 PORT A or DDR A: Data Direction Register A
E811 CRA: Control Register A
E812 PORT B or DDR B: Data Direction Register B
E813 CRB: Control Register B
Control registers:
CRA:
bit meaning
--- -------
7 CA1 active transition flag. 1= 0->1, 0= 1->0
6 CA2 active transition flag. 1= 0->1, 0= 1->0
5 CA2 direction 1 = out | 0 = in
4 CA2 control Handshake=0 | Manual=1 | Active: High=1 Low=0
3 CA2 control On Read=0 | CA2 High=1 | IRQ on=1, IRQ off=0
Pulse =1 | CA2 Low=0 |
2 Port A control: DDRA = 0, IORA = 1
1 CA1 control: Active High = 1, Low = 0
0 CA1 control: IRQ on=1, off = 0
CRB works identical for CB1 and CB2, except for the differences in
handshaking.
The Cx2 handshake is not identical between ports. For port A, the handshake
is on reading the PORT A register, for CB2 the handshake is sent on writing
the PORT B register.
On the listening side:
BIT 3 LOW with CA2: CA2 is now controlled by two events:
(i) CA1 active transition sets it high ("Data Valid")
(ii) a READ operation sets it low ("Data Accepted").
On the talking side:
BIT 3 LOW with CB2: CB2 is now controlled by two events:
(i) CB1 active transition sets it high ("Ready For Data")
(ii) a WRITE operation sets it low ("Data Valid").
Bit 2 HIGH: Causes pulse output, CA2 or CB2 going low for one cycle only
after a read or write operation. This pulse may be too short for some uses.
For operation with a sending and a receiving PIA one would connect
talker listener
------ --------
Port B -> Port A
CB2 -> CA1 with active = 1->0 (data valid)
CB1 <- CA2 with active = 1->0 (data accepted and ready for more)
Use of PIA signals in a PET:
PIA 1
E810 PORT A 7 Diagnostic sense (pin 5 on the user port)
6 IEEE EOI in
5 Cassette sense #2
4 Cassette sense #1
3-0 Keyboard row select (through 4->10 decoder)
E811 CA2 output to blank the screen (old PETs only)
IEEE EOI out
CA1 cassette #1 read line
E812 PORT B 7-0 Contents of keyboard row
Usually all or all but one bits set.
E813 CB2 output to cassette #1 motor: 1=on, 0=off
CB1 screen retrace detection in
PIA 2
E820 PORT A Input buffer for IEEE data lines
E821 CA2 IEEE NDAC out
CA1 IEEE ATN in
E822 PORT B Output buffer for IEEE data lines
E823 CB2 IEEE DAV out
CB1 IEEE SRQ in
The VIA
-------
The VIA is a superset of the PIA. Many of the principles apply here as
well, though the organisation is slightly different.
The VIA has two ports, PA and PB, 4 control lines C[AB][12], an 8-bit shift
register SR and 2 timers TA and TB.
Like the PIA, the Cx1 lines are input only, the Cx2 lines are I or O.
Port A has two registers. One register causes handshaking with CA1 to
happen, the other doesn't. Port B occurs in memory before port A.
There are control registers CRA, CRB, ACR, PCR, and interrupt registers IFR
and IER. The data direction registers DDRA and DDRB have their own
addresses, unlike the PIA.
I'll only describe the extra or different features.
Timers. The VIA has two 16-bit timers T1 and T2. When written to the timers
start counting down on each clock cycle, and when reaching 0000 will flag
and may cause an interrupt or other special action. When the low byte of
the timer is read, the interrupt flag is cleared. When writing to the high
byte clears the flag and starts the timer counting.
T1 has a latch register. This is a place to store the timer value before it
will be used. When T1 reaches 0, the latch value is moved into the timer so
that the countdown may begin all over again, if so enabled.
Ports. PA and PB may be latched, so that on an active transition of CA1 the
value in the PA register is retained indefinitely (or until the next active
transition on that pin), and similarly with CB1 and PB.
The shift register. This 8-bit register is connected to CB2. On command the
SR performs 8 shifts, moving 8 bits to or from CB2 one at a time. The most
significant bit is moved first (the register shifts left). The SR can be
timed by T2 and at the same rate as the 6202, using the phase 2 clock phi2.
Alternatively an external clock may time it.
It seems there are bugs in the shift register. For instance, when doing
tape I/O, the CB2 sound, which uses the SR, must be turned off.
The ACR controls the timers, shift register and latch status of PA and PB.
(T1 has effects on pin PB7, which are not described in the book, but I
suspect they are similar to the features of the CIA in this respect. -Olaf)
ACR E84B
7-6 Timer 1 control
0 = PB7 unused
0 0 = one shot
0 1 = continuous, i.e. on underflow timer restarts at latch value.
(The following 3 lines are guessed, based on the Amiga's CIA description)
1 = PB7 used
1 0 = T1 underflow toggles PB7
1 1 = T1 underflow pulses PB7
5 Timer 2 control
0 = one shot
1 = count set no. of PB6 pulses
4-2 Shift register control
000 = shift reg disabled
001 = shift in by timer 2
010 = shift in by phi2
011 = shift in by external clock (PB6?)
100 = free run by timer 2 (setting for sound)
this means keep shifting the same byte out over and over.
T2 is hereby set to continuous mode.
101 = shift out by timer 2
110 = shift out by phi2
111 = shift out by external clock (PB6?)
1 Port B latch
0 = disabled
1 = enabled on CB1 transition (in/out)
0 Port A latch
0 = disabled
1 = enabled on CA1 transition (in)
The Periheral Control Register PCR controls the operating modes of the
control lines CA1-CB2.
PCR E84C
7-5 CB2 control
7 direction
1 = output
1 0 = do handshake
1 0 0 = on write
1 0 1 = pulse?
1 1 = manual CB2 control
1 1 0 = CB1 low
1 1 1 = CB1 high
0 = input
0 0 x = Active high: 0->1
0 1 x = Active low: 1->0
0 x 0 = Clear IFR/ORB (don't ask me what this means -Olaf)
0 x 1 = Clear IFR
4 CB1 control
0 = active transition High
1 = active transition Low
3-1 CA2 control (similar to CB2 control)
3 direction
1 = output
1 0 = do handshake
1 0 0 = on read
1 0 1 = pulse
1 1 = manual CA2 control
1 1 0 = CA1 low
1 1 1 = CA1 high
0 = input
0 0 x = Active high: 0->1
0 1 x = Active low: 1->0
0 x 0 = Clear IFR/ORB (don't ask me what this means -Olaf)
0 x 1 = Clear IFR
The handshaking is not specifically described in the book, so I presume it
is identical to that of the PIA.
Interrupt Flag Register IFR and Interrupt Enable Register IER. These
registers are symmetrical wrt each other. The IER enables specific
interrupts (i.e., allows an event to trigger an interrupt), and the IFR
flags if the event took place.
When writing to the IER bit 7 controls the meaning of the 1 bits in the
data: when set each 1-bit sets the interrupt enable bit, when cleared it
resets that interrupt enable bit.
IFR E84D
IER E84E
7 IFR: master flag bit: 1 when any of the other bits are set
IER: 0 disables, 1 enables interrupts
6 Timer 1 underflow
5 Timer 2 underflow
4 CB1 active transition
3 CB2 active transition
2 Shift register full/empty
1 CA1 active transition
0 CA2 active transition
Use of VIA signals in a PET
---------------------------
E840 PORT B 7 DAV in
6 NRFD in
5 Video retrace in
4 Tape #2 motor (note 2)
3 Tape data out
2 ATN out
1 NRFD out
0 NDAC out
E841 PORT A USER PORT with CA2 handshake (note 1)
E842 DDRB 7-0 normal bits set to 0 0 0 1 1 1 1 0
E843 DDRA 7-0 USER PORT data direction register
E844 Timer 1 LO
E845 Timer 1 HI (set to $FF on system power-on)
E846 Timer 1 latch LO
E847 Timer 1 latch HI
E848 Timer 2 LO
E849 Timer 2 HI
E84A Shift register
E84B ACR Aux. control register; set to $00 at power on
7-6 timer 1 control
5 timer 2 control
4-2 shift register control
1 port B latch
0 port A latch
E84C PCR Peripheral Control Register; set to $0C or $0E at power on
7-5 CB2 control (user port pin M) (note 3)
4 CB1 control (note 3)
3-1 CA2 control (graphics mode) (note 3)
0 CA1 control (note 3)
E84D IFR Intertrupt Flag Register; set to $00 at power on
7 IRQ on/off
6 T1 interrupt flagged
5 T2 interrupt flagged
4 CB1 interrupt flagged
3 CB2 interrupt flagged
2 shift register interrupt flagged
1 CA1 interrupt flagged
0 CA2 interrupt flagged
E84E IER Interrupt Enable Register; set to $80 at power on
7 1=enable, 0=disable
6-0 enable interrupts; same bits as in IFR.
E84F PORTA USER PORT without CA2 handshake
Note 1: E84F is the preferred user port register, since CA2 controls screen
graphics.
Note 2: The motor is on when this line is low, and off when it is high.
Note 3: CA1 is connected to pin B of the user port. Pins B-L correspond to
port A, which is invaiably E84E. CB2 (connected to the shift register) also
connects to pin M of the user port; square wave tones (see chapter 9 of
"Programming the PET/CBM") use these facts. CB1 signals input from cassette
#2. CA2 controls screen graphics: it is configured for output, and, when
low, gives lower case characters and others. When high, the mode is upper
case and graphics.
IEEE Port Pinouts
-----------------
This info taken from Transactor Volume 4, Issue 05.
rear view for IEEE and User port:
1 2 3 4 5 6 7 8 9 10 11 12
--- --- --- --- --- --- --- --- --- --- --- ---
===================================================
--- --- --- --- --- --- --- --- --- --- --- ---
A B C D E F H J K L M N
The User port is the second port from the left, the IEEE-488 port is
the third port.
PET IEEE
Pin# Pin# Mnemonic Definition
-----------------------------------
1 1 DIO1 Data Input/Output Line #1
2 2 DIO2 Data Input/Output Line #2
3 3 DIO3 Data Input/Output Line #3
4 4 DIO4 Data Input/Output Line #4
5 5 EOI End Or Identify (PIA1 PA6 in, PIA1 CA2 out)
6 6 DAV Data Valid
7 7 NRFD Not Ready For Data
8 8 NDAC Not Data Accepted
9 9 IFC Interface Clear
10 10 SRQ Service Request (PIA2 CB1)
11 11 ATN Attention (VIA PB2 out, PIA2 CB1)
12 12 GND Chassis Ground (IEEE cable shield)
A 13 DIO5 Data Input/Output Line #5
B 14 DIO6 Data Input/Output Line #6
C 15 DIO7 Data Input/Output Line #7
D 16 DIO8 Data Input/Output Line #8
E 17 REN Remote Enable
F 18 GND DAV Ground
H 19 GND NRFD Ground
J 20 GND NDAC Ground
K 21 GND IFC Ground
L 22 GND SRQ Ground
M 23 GND ATN Ground
N 24 GND Data Ground (DIO1-8)
Pin# Function Description
-------------------------
1 Ground System Ground
2 TV Video Video Out for external displays
3 SRQ Connected to IEEE-488 SRQ (PIA2 CB1)
4 EOI Connected to IEEE-488 EOI (PIA1 PA6 in, PIA1 CA2 out)
5 Diagnostic Sense (PIA1 PA7)
Held low causes power up to diagnostic routines or monitor
6 Read 1 Connected to cassette #1 read line (PIA1 CA1)
7 Read 2 Connected to cassette #2 read line (VIA CB1)
8 Write Diagnostic tape write verify
9 Vert TV Vertical for external displays
10 Horiz TV Horizontal for external displays
11 GND
12 GND
A GND
B CA1 Edge sensitive input for 6522 VIA
C PB0 PB0-7 are independently programmable
D PB1 for Input or Output
E PB2
F PB3
H PB4
J PB5
K PB6
L PB7
M CB2 Special IO pin of VIA, connected to shift register
N GND Digital ground
Cassette port
-------------
1 2 3 4 5 6
--- --- --- --- --- ---
==========================
--- --- --- --- --- ---
A B C D E F
Pin# Name Description
----------------------
A-1 GND Digital Ground
B-2 +5V +5 Volts to operate cassette circuitry only
C-3 Motor Computer controlled +6V for cassette motor
D-4 Read Read line from cassette
E-5 Write Write line to cassette
F-6 Sense Monitors closure of any locking type cassette switch
-Olaf.
--
___ Olaf 'Rhialto' Seibert rhialto@mbfys.kun.nl Ooey-Gooey-Fluffy-Barfie
\X/ I'm not weird, I'm differently perceived. D787B44DFC896063 4CBB95A5BD1DAA96
; Commodore PET 8032 ROM Memory Map
; V1.2 19 DEC 1994
;
; Data types in headers (for reassembler):
;
; DATA Misc data
; TEXT String terminated with 00
; WORD Vectors in LO/HI byte pairs
; CHIP I/O Area
; EMPTY ROM containing FF's or AA's
;
;
; BASIC 4.0 interpreter ROM ($B000 - $CFFF)
;
b000 stmdsp BASIC Command Vectors WORD
b066 fundsp BASIC Function Vectors WORD
b094 optab BASIC Operator Vectors DATA
; Each Operator Vector is preceded by a priority code.
b0b2 reslst BASIC Command Keyword Table DATA
b13d msclst BASIC Misc. Keyword Table DATA
b154 oplist BASIC Operator Keyword Table DATA
b161 funlst BASIC Function Keyword Table DATA
b1b1 - Additional Action Keywords DATA
b20d errtab Error Message Table DATA
b306 okk Misc. Messages DATA
b322 fndfor Find FOR/GOSUB Entry on Stack
b350 bltu Open Space in Memory
b393 getstk Check Stack Depth
b3a0 reason Check Memory Overlap
b3cd omerr Output ?OUT OF MEMORY Error
b3cf error Error Routine
b3f4 errfin Break Entry
b3ff ready Restart BASIC
b406 main Input & Identify BASIC Line
b41f main1 Get Line Number & Tokenise Text
b425 inslin Insert BASIC Text
b4b6 linkprg Rechain Lines
b4e2 inlin Input Line Into Buffer
b4fb crunch Tokenise Input Buffer
b5a3 fndlin Search for Line Number
b5d2 scrtch Perform [new]
b5ee clear Perform [clr]
b622 stxpt Reset TXTPTR
b630 list Perform [list]
b6ab qplop Handle LIST Character
b6de for Perform [for]
b74a newstt BASIC Warm Start
b75f ckeol Check End of Program
b77c gone Prepare to execute statement
b785 gone3 Perform BASIC Keyword
b7a7 - Perform [go]
b7b7 restor Perform [restore]
b7c6 stop Perform [stop], [end], break
b7ee cont Perform [cont]
b808 run Perform [run]
b813 gosub Perform [gosub]
b830 goto Perform [goto]
b85d return Perform [return]
b883 data Perform [data]
b891 datan Search for Next Statement / Line
b8b3 if Perform [if]
b8c6 rem Perform [rem]
b8d6 ongoto Perform [on]
b8f6 linget Fetch linnum From BASIC
b930 let Perform [let]
b94f putint Assign Integer
b961 ptflpt Assign Floating Point
b964 putstr Assign String
b96e puttim Assign TI$
b9ab -get character string
b9ba getspt Add Digit to FAC#1
ba4e ?
ba88 printn Perform [print#]
ba8e cmd Perform [cmd]
baa2 strdon Print String From Memory
baa8 print Perform [print]
bac0 varop Output Variable
bad2 - Add zero terminator to string
badf crdo Output CR/LF
baf0 comprt Handle comma, TAB(, SPC(
bb1d strout Output String
bb3a outspc Output Format Character
bb41 -Print '<cursor right>'
bb44 -Print '?'
bb46 - Output Character in A
bb4c doagin Handle Bad Data
bb7a get Perform [get]
bba4 inputn Perform [input#]
bbbe input Perform [input]
bbe8 bufful Read Input Buffer
; Bufful scans for a null input and calls DATA to skip to the next statement
; On old PETs, END was called, thereby crashing the program.
bbf5 qinlin Do Input Prompt
bc02 read Perform [read]
bc31 rdget General Purpose Read Routine
bcf6 exint Input Error Messages DATA
bd19 next Perform [next]
bd5b donext Check Valid Loop
bd84 frmnum Confirm Result
bd98 frmevl Evaluate Expression in Text
be81 eval Evaluate Single Term
bea0 pival Constant - PI DATA
bea5 qdot Continue Expression
becc - Evaluate <equal>
bee9 parchk Expression in Brackets
beef chkcls Confirm Character
beef -Test ')'-
bef2 -Test '('-
bef5 -Test comma-
bef7 -Confirm Character in A
bf00 synerr Output ?SYNTAX Error
bf05 domin Set up NOT Function
bf0c Patch for getspt
bf21 ?
bf2e Patch for [input]
bf41 Unused EMPTY
bf8c isvar Search for Variable
bfad tisasc Convert TI to ASCII String
c003 -read real time clock
c047 isfun Identify Function Type
c051 strfun Evaluate String Function
c071 numfun Evaluate Numeric Function
c086 orop Evaluate <or>
c089 - Evaluate <and>
c0b6 dorel Evaluate <less> (comparison)
c0bb numrel Numeric Comparison
c0ce strrel String Comparison
c11e dim Perform [dim]
c12b ptrget Identify Variable
c187 ordvar Locate Ordinary Variable
c1b6 isletc Does A hold an alphabetic character?
c1c0 notfns Create New Variable
c1cb notevl Create Variable
c2c8 aryget Allocate Array Pointer Space
c2d9 n32768 Constant 32768 in Flpt DATA
c2dd intidx Evaluate Text for Integer
c2ea ayint FAC#1 to Positive Integer
c2fc isary Get Array Parameters
c343 fndary Find Array
c370 bserr ?BAD SUBSCRIPT
c373 - ?ILLEGAL QUANTITY
c378 - ?REDIM'D ARRAY
c38c notfdd Create Array
c439 inlpn2 Locate Element in Array
c477 umult Number of Bytes in Subscript
c4a8 fre Evaluate <fre>
c4bc givayf Convert Integer in (AC/YR) to Flpt
c4c9 pos Evaluate <pos>
c4cf errdir Confirm Program Mode
c4d7 - ?UNDEF'D FUNCTION
c4dc - Perform [def]
c50a getfnm Check Syntax of FN
c51d fndoer Perform [fn]
c58e strd Evaluate <str$>
c598 strlit Set Up String
c5fe putnw1 Save String Descriptor
c61d getspa Allocate Space for String
garbag Garbage Collection
dvars Search for Next String
grbpas Collect a String
c74f cat Concatenate Two Strings
c78c movins Store String in High RAM
c7b5 frestr Perform String Housekeeping
c811 frefac Clean Descriptor Stack
c822 chrd Evaluate <chr$>
c836 leftd Evaluate <left$>
c862 rightd Evaluate <right$>
c86d midd Evaluate <mid$>
c897 pream Pull String Parameters
c8b2 len Evaluate <len>
c8b8 len1 Exit String Mode
c8c1 asc Evaluate <asc>
c8d1 gtbytc Evaluate Text to 1 Byte in XR
c8d4 -Eval Byte Parameter
c8e3 val Evaluate <val>
c8eb strval Convert ASCII String to Flpt
c921 getnum Get parameters for POKE/WAIT
c92d getadr Convert FAC#1 to Integer in LINNUM
c943 peek Evaluate <peek>
c95a poke Perform [poke]
c963 wait Perform [wait]
c97f faddh Add 0.5 to FAC#1
c986 fsub Perform Subtraction
c989 - Evaluate <subtract>
c998 fadd5 Normalise Addition
c99d fadd Perform Addition
c9a0 - Evaluate <add>
ca7d negfac 2's Complement FAC#1
cab4 overr Output ?OVERFLOW Error
cab9 mulshf Multiply by Zero Byte
caf2 fone Table of Flpt Constants DATA
;caf2 1.00
;caf7 #03 (counter)
;caf8 0.434255942
;cafd 0.57658454
;cb02 0.961800759
;cb07 2.885390073
;cb0c 0.707106781 SQR(0.5)
;cb11 1.41421356 SRQ(2)
;cb16 -0.5
;cb1b 0.693147181 LOG(2)
;
cb20 log Evaluate <log>
cb5e fmult Perform Multiply
cb61 - Evaluate <multiply>
cb8f mulply Multiply by a Byte
cbc2 conupk Load FAC#2 From Memory
cbed muldiv Test Both Accumulators
cc0a mldvex Overflow / Underflow
cc18 mul10 Multiply FAC#1 by 10
cc2f tenc Constant 10 in Flpt DATA
cc34 div10 Divide FAC#1 by 10
cc3d fdiv Divide FAC#2 by Flpt at (AC/YR)
cc45 fdivt Divide FAC#2 by FAC#1
cc48 - Evaluate <divide>
ccd8 movfm Load FAC#1 From Memory
ccfd mov2f Store FAC#1 in Memory
cd0a - Store FAC#1 at (AC/YR)
cd32 movfa Copy FAC#2 into FAC#1
cd42 movaf Copy FAC#1 into FAC#2
cd51 round Round FAC#1
cd61 sign Check Sign of FAC#1
cd6f sgn Evaluate <sgn>
cd8e abs Evaluate <abs>
cd91 fcomp Compare FAC#1 With Memory
cdd1 qint Convert FAC#1 to Integer
ce02 int Evaluate <int>
ce29 fin Convert ASCII String to a Number in FAC#1
cee9 n0999 String Conversion Constants DATA
cef8 Unused EMPTY
cf78 inprt Output 'IN' and Line Number
cf93 fout Convert FAC#1 to ASCII String
d01e foutim Convert TI to String
d0c7 fhalf Table of Constants DATA
d108 sqr Evaluate <sqr>
d112 fpwrt Evaluate <power>
d14b negop Negate FAC#1
d14b - Evaluate <greater>
d156 logeb2 Table of Constants DATA
;d156 1.44269504 (1/LOG to base 2 e)
;d15b #07 (counter)
;d15c 2.149875 E-5
;d161 1.435231 E-4
;d166 1.342263 E-3
;d16b 9.6414017 E-3
;d170 5.550513 E-2
;d175 2.402263 E-4
;d17a 6.931471 E-1
;d17f 1.00
;
d184 exp Evaluate <exp>
d1d7 polyx Series Evaluation
d221 rmulc Constants for RND DATA
d229 rnd Evaluate <rnd>
d282 cos Evaluate <cos>
d289 sin Evaluate <sin>
d2d2 tan Evaluate <tan>
d2fe pi2 Table of Trig Constants DATA
;d2fe 1.570796327 pi/2
;d303 6.28318531 pi*2
;d308 0.25
;
;d30d #05 (counter)
;d30e -14.3813907
;d313 42.0077971
;d318 -76.7041703
;d31d 81.6052237
;d322 -41.3417021
;d327 6.28318531
;
d32c atn Evaluate <atn>
d35c atncon Table of ATN Constants DATA
;d35c #0b (counter)
;d35d -0.000684793912
;d362 0.00485094216
;d367 -0.161117018
;d36c 0.034209638
;d371 -0.0542791328
;d376 0.0724571965
;d37b -0.0898023954
;d380 0.110932413
;d385 -0.142839808
;d38a 0.19999912
;d38f -0.333333316
;d394 1.00
;
d399 initat CHRGET For Zero-page
d3b1 rndsed RND Seed For zero-page DATA
;d3b1 0.811635157
d3b6 init BASIC Cold Start
initcz Initialize BASIC RAM
d417 initms Output Power-Up Message
initv Initialize Vectors
d44b words Power-Up Message DATA
d472 ?
;
; Machine Language Monitor
;
d4ba *Get Command
d531 Print Space
d534 New Line
d539 Increment Pointer
d544 Commands DATA
d54c Command Vectors DATA
d55c '<cr> pc irq sr ac xr yr sp' DATA
d579 ?
d587 Perform [r]
d5bc Perform [m]
d5fb Perform [;]
d61d Perform [:]
d633 Perform [g]
d66b Perform [x]
d675 Perform [l/s]
d722 Output 2-digit Byte
d731 Output 2 Ascii Chars
d73a Byte to 2 Ascii
d744 Swap Add_ with Add_
d7a4 Print '?'
d7af Perform [record]
d873 Perform [catalog/directory]
d942 Perform [dopen]
d977 Perform [append]
d9d2 Perform [header]
da07 Perform [dclose]
da65 Perform [collect]
da7e Perform [backup]
daa7 Perform [copy]
dac7 Perform [concat]
db0d Perform [dsave]
db3a Perform [dload]
db55 Perform [rename]
db66 Perform [scratch]
de9e ? DATA
dea4 ? DATA
dec2 Unused EMPTY
;
; Editor (E000)
;
e202 Output to Screen
e3b6 Output <CR>
e442 Main IRQ Entry Point
e600 Exit Interrupt
e788 Unused EMPTY
;
; Kernel (F000-FFFF)
; Tape processing, IEEE-488, jump table
;
f185 Output Kernal Error Message
f2a6 clrchn Restore Default I/O
f266 chrout Output One Character
f2dd closet Perform [close]
f401 verfyt Perform [load]
f4f6 verfyt Perform [verify]
f560 opent Perform [open]
f6c3 syst Perform [sys]
f6dd savet Perform [save]
f7af chkin Set Input Device
f7fe chkout Set Output Device
fd16 - Power-Up RESET Entry
fd49 - NMI Transfer Entry
fd4c - Kernal Reset Vectors WORD
fd5d - Unused EMPTY
;
; PET 8032 Jump Table
;
ff93 Perform [concat]
ff96 Perform [dopen]
ff99 Perform [dclose]
ff9c Perform [record]
ff9f Perform [header]
ffa2 Perform [collect]
ffa5 Perform [backup]
ffa8 Perform [copy]
ffab Perform [append]
ffae Perform [dsave]
ffb1 Perform [dload]
ffb4 Perform [catalog/directory]
ffb7 Perform [rename]
ffba Perform [scratch]
ffc0 Perform [open]
ffc3 Perform [close]
ffc6 chkin Set Input
ffc9 chkout Set Output
ffcc clrch Restore I/O Vector
;ffcf chrin Input Vector, chrin
ffd2 chrout Output Vector, chrout
ffd5 Perform [load]
ffd8 Perform [save]
ffdb Perform [verify]
ffde sys Perform [sys]
ffe4 jmp getin Get From Keyboad
;fff6 Vectors
fff6 [AAAA] - WORD
fff8 [AAAA] - WORD
;fffa Transfer Vectors
fffa [fd49] NMI WORD
fffc [fd16] RESET WORD
fffe [e442] IRQ WORD