This I/O map applies to c16/116/+4 computers
(c) 1990-1994 by Michael Stiller.
Extension port pinouts (50 pin female)
25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
CC BB AA Z Y X W V U T S R P N M L K J H F E D C B A
1 gnd A gnd
2 + 5V B C1 low
3 + 5V C BRESET --
4 IRQ -- D RAS --
5 R/W E I0 (clock0)
6 C1 high F A15
7 C2 low H A14
8 C2 high J A13
9 CS1 -- K A12
10 CS0 -- L A11
11 CAS -- M A10
12 MUX N A9
13 BA P A8
14 D7 R A7
15 D6 S A6
16 D5 T A5
17 D4 U A4
18 D3 V A3
19 D2 W A2
20 D1 X A1
21 D0 Y A0
22 AEC Z nc
23 extern Audio AA nc
24 02 (clock2) BB nc
25 gnd CC gnd
Verified with the CBM Plus/4 User's Manual.
Note:pins marked with '--' appear in the schematic as low active
User port pinouts (24 pin male)
1 2 3 4 5 6 7 8 9 10 11 12
-- -- -- -- -- -- -- -- -- -- -- --
-- -- -- -- -- -- -- -- -- -- -- --
A B C D E F H J K L M N
1 gnd A gnd
2 +5V B P0
3 BRESET -- C RxD
4 P2 D RTS
5 P3 E DTR
6 P4 F P7
7 P5 H DCD
8 RxC J P6
9 ATN K P1
10 9V AC L DSR
11 9V AC M TxD
12 gnd N gnd
Verified with the CBM Plus/4 User's Manual.
Note:pins marked with '--' appear in the schematic as low active
These pinouts are from the book:
Wilhelm Besenthal/Jens Muus
'Alles ueber den Plus/4'
Markt&Technik Verlag AG
ISBN3-89090-410-6
Memory Map Overview
from the CBM Plus/4 User's Manual
Address RAM ROM
$ffff End of RAM ROM Bank High
$fffe IRQ Vector
$fffc RES Vector
$fffa NMI Vector
$ff81 Kernal Jump Table
$fd00 I/O Register/TED Register
End if Basic RAM+1
$fc00 ROM-Banking routines
$d800 Operating System
$d000 Character Table
$c000 Basic extensions
$bfff ROM Bank Low
$8000 BASIC
$4000 start of basic ram
if graphic
$3fff
graphic bitmap
$2000
color map (graphic)
$1c00
luminance (graphic)
$1800
$1000 start of basic ram
(no graphic)
$0c00 character bytes
(display)
$0800 attribute bytes
Detailed I/O Port Map as located in Plus/4 and similar CBM Computers
(C16/116/+4)
Most ports are not fully decoded by a chip called 7700-xx in the
schematic, so they may appear
copied on different memory locations.
Addr $ Chip/Port Usage:
$fd00-fd03 ACIA 6551A used for RS232 (for bits see +4 manual)
$fd00 DATA port
$fd01 STATUS port
$fd02 COMMAND port
$fd03 CONTROL port
$fd04-fd07 ACIA copy
$fd08-fd0b ACIA copy
$fd0c-fd0f ACIA copy
$fd10 PIO 6529B User Port PIO (P0-P7)
Bit 2 (P2) is used to detect
if play on cassette is pressed
(CST sense)
$fd11-fd1f PIO copies
$fd20-fd2f free not connected
$fd30 PIO 6529B Keyboard PIO Keyboard Matrix Connector
P0 15
P1 18
P2 7
P3 12
P4 11
P5 10
P6 5
P7 1
$fd31-fd3f PIO copies
$fd40-fdcf free not connected
$fdd0-fddf ADDR CLK used for module select?
in the schematic this is
the clk/in for 4 D-FlipFlops
located in the 74LS175 chip which generates
the C1,C2 low/high signals
$fde0-fdff free not connected *
$fe00-fe1f free not connected *
$fe20-fe3f free not connected *
$fe40-fe5f free not connected *
$fe60-fe7f free not connected *
$fe80-fe9f free not connected *
$fea0-febf free not connected *
$fec0-fedf TIA 6523A if you have a CBM 1551 as device #9
then the TIA located in the paddle of
you drive will appear at this location
for details see $fee0-feff
$fee0-feff TIA 6523A if you have a CBM 1551 as device #8
then the TIA located in the paddle of
your drive will appear at this location
$fee0 TIA PORT A (DATA)
$fee1 TIA PORT B (STATUS)
$fee2 TIA PORT C (HANDSHAKE)
$fee3 TIA PORT A data direction register
$fee4 TIA PORT B data direction register
$fee5 TIA PORT C data direction register
$fee6 not connected
$fee7 not connected
$fee8-feef TIA copy
$fef0-fef7 TIA copy
$fef8-feff TIA copy
TIA Notes:
The TIA 6523A is a triport interface adapter which is located in the
paddle of the 1551 disk drives. The drivenumber causes the TIA to appear
at the corresponding memory addresses as mentioned above.
The address decoding stuff is done by another chip located in the
1551 paddle, called 8700-011 ?
The TIA port a is used as direct 8 bit data connection between the
computer and the drive. (It is called TCBM Bus in the 1551 schematic)
The other TIA ports are used for other TCBM Bus signals (handshake etc.)
They are connected as follows:
Port bit used for
B 0 status 0
B 1 status 1
C 6 DAV signal
C 7 ACK signal
The marked (*) port may be intended as additional drive locations,but
they are not supported by the 1551 drives.
(c) 1990-1994 by Michael Stiller.
The informations here are given without warranty.
May not be modified without permission.
For comments,questions,donations etc. write to
stille00@marvin.informatik.uni-dortmund.de
(
geocities.com/timessquare/arcade/2045/docs) (
geocities.com/timessquare/arcade/2045) (
geocities.com/timessquare/arcade) (
geocities.com/timessquare)