Amstrad CPC 6128
128K, a 3 in drive and CP/M Plus; the PAL beside the Gate Array banks the second 64K.
Open the Amstrad CPC 6128 in Retro Bench- Also
- CPC6128 (Schneider CPC 6128)
- Year
- 1985
- CPU
- Z80A @ 4 MHz
- RAM
- 128 KB in two 64 KB banks (sixteen 4164-type DRAM)
- ROM
- 48 KB: 32 KB OS + BASIC 1.1, 16 KB AMSDOS
- Video
- Gate Array 40010 + 6845, same modes as the 464
- Sound
- AY-3-8912, 3 voices, stereo jack
- OS
- Locomotive BASIC 1.1, AMSDOS, CP/M Plus and CP/M 2.2 on disk
Chips
| Chip | Where | Role |
|---|---|---|
| Amstrad 40010 Gate Array (HSG3130 / HSG3170) | IC116 (HSG3130/3170; socket J105) | Video (pixels, palette, RGB, sync), DRAM timing, ROM/RAM selection, CPU clock and wait states, interrupts |
| Amstrad 40030 PAL (PAL16L8) | IC118 (socket J106) | 128K RAM banking: second-bank /CAS and the A14/A15 remap for the 6128 RAM configurations |
| Z80A CPU | IC111 (Z8400APS) | Main CPU (8-bit, 40-DIP) |
| MC6845 CRT controller | IC108 (HD6845SP) | Makes sync, display enable, cursor and the video RAM refresh addresses. |
| 23256 mask ROM 32K x 8 | IC103 (TMM23256P-1953; Amstrad 40025 on later boards) | 32K x 8 mask ROM in the 27256 pinout. |
| 23128 Mask ROM 16K×8 | IC204 (AMSDOS ROM, TMM23128P, Amstrad 40015) | BASIC and KERNAL ROMs (C16, Plus/4, C64C short board, C128) |
| NEC uPD765A floppy disk controller | IC201 (uPD765AC-2; Z765APS on later boards) | Floppy disk controller for the internal 3 in drive and drive B |
| 4164 DRAM 64K×1 | IC127-IC134 bank 0 (first 64K), IC119-IC126 bank 1 (second 64K) (HM4864U-2 or MSM3764-20RS) | Main RAM (8 chips = 64 KB) |
| 8255A-5 programmable peripheral interface | IC107 (M5L8255AP-5) | Three 8-bit programmable I/O ports (A, B, C). |
| AY-3-8912 sound chip | IC102 | Three-voice programmable sound generator with one 8-bit I/O port |
Ports and connectors
- 5V DC socket (from the monitor), DC jack (Hosiden HEC0470-01-630, Amstrad part 170024; spec sheet calls it a 5 mm socket)
- 12V DC lead (to the monitor, for the disk drive), DC plug on a flying lead (cord 14550401), center negative
- Monitor socket (RGB), 6-pin DIN 240 degrees
- Joystick port, DE-9 male on the computer (9 pin D)
- Expansion port (rear), 50-way 0.1 in PCB edge (25 + 25), slot between 21/23 and 22/24
- Printer port (rear), 34-way 0.1 in PCB edge (17 + 17), Centronics numbering 1-17 / 19-35
- Disk drive 2 socket (second drive), 34-way 0.1 in PCB edge (17 + 17), odd/even numbering
- Tape socket (external cassette recorder), 5-pin DIN 180 degrees
- Stereo socket (headphones / amplifier), 3.5 mm stereo jack
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | +5 V | Z80A pin 11; 40010 pin 6; 40010 pin 25; 40030 pin 20; 765 pin 40 |
| +12 V | +12 V UNVERIFIED | 12 V lead outer sleeve; drive power connector CD202 |
| GND | 0 V | Z80A pin 29; 40010 pin 15; 40010 pin 26; 40010 pin 36; 765 pin 20 |
Symptoms
- Red power LED on, black screen: check 40010, Z80A, 23256, 6845, 4164
- BASIC works, CP/M Plus or |BANK commands fail: check 40030, 4164
- Garbage screen, no sign-on: check 4164, 40030, 40010
- "Drive A: disk missing": check 765
- Drive B not seen: check 765
- No sound: check AY-3-8912, 8255A
- External tape will not load: check 8255A