Commodore 128 128D Service Manual (314001-08)
The Commodore 128 / 128D Service Manual is Commodore Business Machines' own service manual for the Commodore 128 and the 128D, part number 314001-08, dated November 1987. 104 pages.
The scan carries a text layer.
Contents
[edit | edit source]| Section | What it covers |
|---|---|
| Specifications | Commodore's own figures for 64 mode, 128 mode, CP/M mode, the keyboard, inputs and outputs, and power requirements |
| Parts lists | PCB assembly 310379 revisions 6 and 7 in full, plus the case, keyboard and 128D assemblies |
| Theory of operation | The processor bus, the display bus, the Z80 bus, memory management, the two clock domains and 2 MHz mode |
| Pin assignments | 8502, Z80B, 8722 MMU, 8721 PLA, 8564 VIC, 8563 VDC, 6581 SID, 6526 CIA |
| Schematics | Sheet set for the 310379 board |
What this manual settles
[edit | edit source]- The complete designator map. U6 is the 8502 (315020-01), U7 the 8722-R1 MMU (310389-01), U10 the Z80B (906150-02, a 6 MHz part), U11 the 8721-R3 PLA (315012-01), U21 the 8564-R4 VIC (315009-01), U22 the 8563-R7 VDC (315014-01), U5 the 6581 SID (906112-01), U1 and U4 the two 6526 CIAs, U28 the 8701 clock generator, U19 a 2016 static RAM for colour, U23 and U25 the two 4416 video DRAMs, U38–U53 the sixteen 4164 DRAMs that make up the 128 KB, and U32–U36 the ROM sockets (U32 the combined C64 KERNAL and BASIC 251913-01, U33 BASIC $4000, U34 BASIC $8000, U35 KERNAL $C000, U36 the blank function-ROM socket).
- There is one on-board regulator, U59, a 7812. The 5 V logic rail comes from the external supply, exactly as on the Commodore 64.
- Commodore's own power figure is 117 V AC, 60 Hz, 15 W for the NTSC machine.
- The Z80 clock is a 4 MHz clock gated to the low half of the 1 MHz clock, which is why the effective Z80 rate is about 2 MHz. Commodore states this in the clocking section, so the "4 MHz but really 2 MHz" figure is documented rather than folklore.
- 2 MHz mode disables the VIC as a display processor. Commodore is explicit: bit 0 of VIC register 48 selects 2 MHz, and during 2 MHz operation the VIC cannot be used as a video display chip. The system clock is also forced back to 1 MHz during refresh and I/O access regardless of that bit.
- RAM expansion is specified to 512 K, using the RAM disk option — not to 1 MB.
What this manual does not contain
[edit | edit source]- No capacitor value table presented as such — the electrolytics appear in the parts lists by designator, as with every Commodore manual of the period.
- No fault or symptom chart of the kind Commodore printed in the C64 service manual.
- No coverage of the 1571 or 1581 drives beyond the 128D's integrated mechanism.
Pages that cite this document
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Download: Commodore 128 128D Service Manual 314001-08 (1987 Nov).pdf