C128DCR Assembly 250477

  • Released in 1986.
  • Schematic Number 252451.
  • Mainboard used in the low cost version of the C128D (C128DCR).
  • Plastic case instead of a metal case like the C128D.
  • Improved 80 column mode video chip.

Specs

  • CPU : 8502 @ 1–2 MHz / Zilog Z80A, or Zilog Z80B @ 4 MHz
  • RAM : 128kB DRAM
  • ROM (C64 Mode) : 16kB ROM Total - 8k BASIC, 8k Kernal
  • ROM (C128 Mode) : 64kB ROM Total - 48k BASIC, 16k Kernal, 16k C128 BIOS
  • ROM (CP/M) : 4kB CPM/BIOS
  • Graphics : VIC-II (40 col mode) / VDC-8563 (80 col mode)
  • Sound : SID
  • Interfaces : 2 Control Ports, A/V, RGBI, Datasette Port, Expansion Port, Serial IEC, TV RF, User Port
  • Keyboard : 92 Keys (External)
  • Power Supply : External Transformer (9V AC + 5V DC)

Schematics

Fig. 1: C128DCR 250477 Mainboard

Capacitor List

Cap   -  Value   - Rating - Type
C35   -  4.7uf   -  50v   - Radial
C61   -  10uf    -  16v   - Radial
C63   -  100uf   -  6.3v  - Radial
C64   -  100uf   -  6.3v  - Radial
C69   -  10uf    -  25v   - Radial
C85   -  10uf    -  25v   - Radial
C88   -  1000uf  -  25v   - Radial
C91   -  1uf     -  50v   - Radial
C92   -  10uf    -  25v   - Radial
C100  -  220uf   -  16v   - Radial
C109  -  10uf    -  25v   - Radial
C115  -  10uf    -  25v   - Radial
C140  -  1uf     -  50v   - Radial  -  Non-Polar
C141  -  1uf     -  50v   - Radial  -  Non-Polar

IC List

PCB ID Chip ID Notes
U1 6526 CIA 1
U2 4066 Quad Bi-Switch
U3 74LS138 Demultiplexor
U4 6526 CIA 2
U5 8580 SID
U6 8502 Processor
U7 8722 MMU
U9 74F32 Quad 2-Input Gate
U10 Z80B Processor
U11 8721 PLA
U17 74ALS373 Octal Latch
U18 2364 ROM - Char
U19 2016 SRAM
U20 4066 Quad Bi-Switch
U21 8564/8566 VIC-II
U22 8568 CRT Control
U23 4464 DRAM - CRT
U25 4464 DRAM - CRT
PCB ID Chip ID Notes
U27 556 Dual Timer
U28 8701C Clock Generator
U32 27256 ROM - Basic
U34 27256 ROM - ROM - Kernal & Basic
U36 23256 ROM - Function
U38 41254 DRAM
U39 41254 DRAM
U40 41254 DRAM
U41 41254 DRAM
U55 74F245 Octal Bus Transceiver
U102 27256 ROM Drive
U103 2016 SRAM
U104 6522A VIA 1
U106 6522A VIA 2
U107 5710 FDC
U108 CX20185/MC28719/LA8200 FDD R/W AMP
U109 UPA2003C NEC

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