Editing Amstrad 6128

{{Infobox computer
| name         = Amstrad CPC 6128
| logo         = [[File:Amstrad CPC logo.svg|150px]]
| developer    = Amstrad
| manufacturer = Amstrad Consumer Electronics plc
| type         = Home computer
| cpu          = Zilog Z80A @ 4 MHz
| memory       = 128 KB RAM, as two 64 KB banks (over 41 KB free in BASIC; 61 KB TPA under CP/M Plus)
| rom          = 48 KB — operating system, Locomotive BASIC and the disc extensions
| storage      = Integrated 3-inch disc drive, Hitachi/Panasonic standard
| graphics     = Motorola 6845 CRT controller
| display      = 160×200×16, 320×200×4 or 640×200×2 from a 27-colour palette
| sound        = General Instrument AY-3-8912, three voices, eight octaves
| input        = 74-key keyboard
| power        = 5 V and 12 V DC from the monitor. '''No mains connection and no internal power supply'''
| os           = Amstrad firmware with Locomotive BASIC; AMSDOS; CP/M Plus supplied
| model        = CPC 6128
}}
<templatestyles src="Template:StyledTable/styles.css" />

The '''Amstrad CPC 6128''' is the disc-based member of the Amstrad CPC range: the same architecture as the [[Amstrad CPC 464]], with '''128&nbsp;KB of RAM''' in place of 64&nbsp;KB and a built-in '''3-inch disc drive''' in place of the cassette deck. It was sold as a complete system with either the GT65 green monitor or the CTM644 colour monitor.

'''The figures on this page are Amstrad's own''', from the ''CPC6128 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual'' hosted on this wiki.<ref name="sm6128">Amstrad Consumer Electronics plc, ''CPC6128 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual''. Hosted at [[Amstrad CPC 6128 Service Manual]]. Source for the technical specification on the back page, the CPC6128 electrical parts list (page 21), the basic hardware analysis and diagnostic flow charts (pages 4 and 8&ndash;11), the alignment checks (pages 12&ndash;15) and the separate GT65 and CTM644 parts lists and voltage charts (pages 22&ndash;28).</ref>

== The monitor is the power supply ==

'''The CPC 6128 has no mains connection and no internal power supply.''' Amstrad's technical specification gives the power supply as "Screen System: 240&nbsp;V AC 50&nbsp;Hz (keyboard and disc drive power supplied by screen system)", and lists two separate connections on the computer:<ref name="sm6128" />

* a '''5&nbsp;mm socket for the 5&nbsp;V supply''', which Amstrad describes as "supplied exclusively from monitor"
* a '''5&nbsp;mm plug and lead that connects to the 12&nbsp;V (disc) power socket on the monitor'''

Both are needed. A 6128 that boots but whose drive does nothing is very often missing the '''12&nbsp;V''' lead, not suffering a drive fault — check that before opening anything. And because the supply lives in the monitor, '''a "dead computer" on a CPC 6128 is a monitor fault until proved otherwise'''; the monitor sections of the service manual carry their own parts lists and '''voltage charts''' for exactly this reason.

== Hardware ==

From Amstrad's technical specification:<ref name="sm6128" />

* '''Z80A at 4&nbsp;MHz'''
* '''128&nbsp;KB of RAM arranged as two 64&nbsp;KB banks''' — over 41&nbsp;KB available to the user in BASIC, 61&nbsp;KB TPA under CP/M Plus
* '''48&nbsp;KB of ROM''' containing BASIC, the operating system and the disc extensions
* '''6845''' CRT controller; '''AY-3-8912''' three-voice, eight-octave sound generator; '''8255''' parallel I/O
* 74-key keyboard — QWERTY with a numeric cluster, cursor and copy cursor, return, enter, shift, caps lock, tab, delete, clear and control
* Three display modes: 4 colours from 27 at 320 × 200, 2 from 27 at 640 × 200, and 16 from 27 at 160 × 200
* Expansion for '''up to 252 additional 16&nbsp;KB ROMs'''
* External sockets: PCB edge connectors for general-purpose expansion and for the Centronics printer port; a second disc drive socket (DI-2 lead); a 9-pin D-type joystick socket; a 6-pin DIN for RGB and sync or luminance and sync; a 5-pin DIN for an external cassette recorder (CL1 lead); a 3.5&nbsp;mm stereo socket for sound out

== The disc system ==

Amstrad's own disc specification:<ref name="sm6128" />

* A '''3-inch system conforming to the Hitachi/Panasonic standard'''
* The software is configured for a '''12&nbsp;ms step rate''' and a '''30&nbsp;ms settling time'''
* '''The system is designed to control a maximum of two drives'''
* CP/M usually assumes an 80-column screen, and Amstrad notes that the 6128's 80-column mode is a prerequisite for most CP/M applications

A second drive attaches through the disc drive 2 socket. The external [[Amstrad DDI-1 / FD-1 Service Manual|FD-1]] drive used with the [[Amstrad CPC 464]] has '''its own integral mains power supply''', so it is not powered from the 6128.

== Servicing ==

The service manual carries, for the computer: a '''basic hardware analysis''' page, '''function diagrams''', a '''software errors''' page, a four-page '''diagnostic flow chart''', four pages of '''alignment checks''', the main PCB layouts, the CPU circuit diagram, and the '''electrical parts list''' giving value, circuit reference and Amstrad part number for every component. For the monitors it carries separate circuit diagrams, PCB layouts, alignment instructions, '''voltage charts''' and parts lists.<ref name="sm6128" />

Later main-board revisions are documented separately in the '''[[Amstrad CPC 464 / CPC 6128 / GT65 / CTM644 / MP3 / CT1 Service Manual Amendment|amendment volume]]''': where a board does not match the original manual's drawing, check the amendment before concluding it has been modified.

== References ==

<references />

== Related pages ==

* [[Amstrad CPC 6128 Service Manual]] · [[Amstrad CPC 464 / CPC 6128 / GT65 / CTM644 / MP3 / CT1 Service Manual Amendment]]
* [[Amstrad CPC 464]] · [[Amstrad CPC 664]] · [[Amstrad 464 Plus / 6128 Plus / GX4000 Service Manual]]
* [[Capacitor Failure Symptoms]] · [[Recommended Tools]] · [[Floppy Drive Repair]]

{{Navbox-Amstrad|state=collapsed}}

[[Category:Amstrad]]