/pub/cbm/schematics/computers/b/

The Commodore Model B service manual and schematic diagrams

Subdirectories

drives@
Disk drives
firmware@
System firmware

Files

314010-06-i.gif 1998-03-29 29724
Service manual, B model computer (Jan. 1985, PN-314010-06), title page
314010-06-ii.gif 1998-03-29 27628
Service manual, B model computer, table of contents
314010-06-p1.gif 1998-03-29 58149
Page 1: block diagram
314010-06-p2.gif 1998-03-29 46741
Page 2: B model parts list
314010-06-p3-left.gif 1998-03-29 60694
 
314010-06-p3-right.gif 1998-03-29 79404
Page 3: 8256048 board layout
314010-06-p4.gif 1998-03-29 74105
Page 4: 8256048 PCB parts
314010-06-p5.gif 1998-03-29 66252
Page 5: 8256048 PCB parts, continued
314010-06-p6-left.gif 1998-03-29 40857
 
314010-06-p6-right.gif 1998-03-29 42640
Page 6: keyboard matrix
4256004-01-left.gif 1998-03-29 35712
 
4256004-01-parts.gif 1998-03-29 58167
 
4256004-01-right.gif 1998-03-29 44598
Switching power supply
4256041-01of15.gif 1998-09-28 346636
Commodore 500 µP, address & data buffers, arbitration logic
4256041-02of15.gif 1998-09-27 264513
system decode & buffer control
4256041-03of15.gif 1998-09-28 292293
VIC; video memory; video bus buffers
4256041-04of15.gif 1998-09-27 192900
SID; 192k DRAM array refresh logic
4256041-05of15.gif 1998-09-28 279736
192k DRAM address mux & control
4256041-06of15.gif 1998-09-27 238991
192k*8 DRAM array [64k standard, 128k optional]
4256041-07of15.gif 1998-09-28 223503
64k DRAM array and address mux
4256041-08of15.gif 1998-09-28 194905
system ROM/RAM array
4256041-09of15.gif 1998-09-28 273583
gameport interface; keyboard interface; RS232C interface
4256041-10of15.gif 1998-09-27 295118
interrupt prioritization; IEEE488 interface; user/game port interface
4256041-11of15.gif 1998-09-28 258517
cassette i/f port
4256041-12of15.gif 1998-09-27 193891
main oscillators & PLL
4256041-13of15.gif 1998-09-28 150690
video output circuit
4256041-14of15.gif 1998-09-27 289443
[List of power filter capacitors for each IC]
4256041-15of15.gif 1998-09-28 211721
[FPLA logic equations]
8088.gif 2002-03-05 155989
 
8088.txt 2002-04-19 10991
The 8088 co-processor board for B-series machines. Reverse engineered by Ruud Baltissen http://ruud.c64.org.
8256043-01of14-left.gif 1998-03-29 61535
 
8256043-01of14-right.gif 1998-03-29 56042
µP, address & data buffers, bus arbitration
8256043-02of14-left.gif 1998-03-29 27636
 
8256043-02of14-right.gif 1998-03-29 47170
master timing
8256043-03of14-left.gif 1998-03-29 40539
 
8256043-03of14-right.gif 1998-03-29 28812
DRAM address & refresh
8256043-04of14-left.gif 1998-03-29 31695
 
8256043-04of14-right.gif 1998-03-29 29054
DRAMs, segments 1-2
8256043-05of14-left.gif 1998-03-29 31825
 
8256043-05of14-right.gif 1998-03-29 29841
DRAMs, segments 3-4
8256043-06of14-left.gif 1998-03-29 27122
 
8256043-06of14-right.gif 1998-03-29 32195
ROM array, 1k×8 static RAM
8256043-07of14-left.gif 1998-03-29 28442
 
8256043-07of14-right.gif 1998-03-29 43144
system decode
8256043-08of14-left.gif 1998-03-29 26866
 
8256043-08of14-right.gif 1998-03-29 32189
CRTC, video shift register
8256043-09of14-left.gif 1998-03-29 22887
 
8256043-09of14-right.gif 1998-03-29 26607
video RAM, address mux, latch
8256043-10of14-left.gif 1998-03-29 45846
 
8256043-10of14-right.gif 1998-03-29 42104
keyboard port, RS232C
8256043-11of14-left.gif 1998-03-29 62363
 
8256043-11of14-right.gif 1998-03-29 50878
user I/O ports, IEEE
8256043-12of14-left.gif 1998-03-29 53904
 
8256043-12of14-right.gif 1998-03-29 50410
SID, dot clock oscillator, expansion connector
8256043-13of14.gif 1998-03-29 27850
video output, power indicator
8256043-14of14.gif 1998-04-17 81574
I.C. count, power consumption
8256059-01.gif 1998-05-28 159301
 
8256059-02.gif 1998-06-02 104788
 
8256059-03.gif 1998-06-02 104071
 
8256059-04.gif 1998-06-02 91274
 
8256059-05.gif 1998-05-29 92943
 
8256059-06.gif 1998-05-29 81230
 
8256059-07.gif 1998-05-29 97112
 
8256059-08.gif 1998-05-29 102877
 
8256059-09.gif 1998-06-01 76584
 
8256059-10.gif 1998-06-02 116642
 
8256059-11.gif 1998-06-02 150061
 
8256059-12.gif 1998-06-02 136422
These schematics seem to be quite identical with 8256043.
README 1998-10-20 1169
General information about the Commodore Model II computers.
README500 1998-10-20 920
Information about the Commodore 500 a.k.a. PET II.
p500-keyboard.txt 1999-07-30 3512
Commodore P500 Keyboard Schematic. Composed by Tony Duell <ard@p850ug1.demon.co.uk>.

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