The CPC472 is a modified Amstrad CPC464 released by Indescomp. Indescomp were the distributors of Amstrad computers in Spain.
Externally, the "CPC472" looks similar to the standard CPC464, except for some monitor differences:
Internally, there is a small sub-PCB which is connected by ribbon cables into the position that would be occupied by the 32K System ROM on the CPC464.
This document describes this sub-PCB, and hopefully it will be decided if the RAM can be used, and if it can, the access method.
The information in this document comes from Vicente Simon.
AMSTRAD COPYRIGHT 1984
PT NO. Z70200
Sub-PCB part list:
|IC103||40037 (TMS27C256)||32K ROM (note 1)|
|IC126||MN4164P||64k x 1bit DRAM|
|IC127||74LS08||Quad 2-Input NAND|
|IC128||74LS136||Quad 2-Input Exclusive-OR|
Drawing of the top of the sub-PCB:
Drawing of the bottom of the sub-PCB:
NOTE: I don't know if all these connections are correct because it is not easy to see the source/destination of some connections. Please e-mail me with corrections.
Signals to/from the sub-PCB:
|D7-D0||Data (note 1)|
|A14-A0||Address (note 2)|
|/ROMDIS||ROM data output disable (note 3)|
|/ROMEN||ROM enable (note 4)|
|VCC||5V D.C. power|
It is not known if /RD,/WR,/IORQ are used to determine the state of /ROMEN.
These are the signals that are present on the ribbon cables which connect the sub-PCB to the main PCB.
|Connection point 1||Connection point 2|
|74LS08 pin 14 (VCC)||MN4164P pin 9 (A7)|
|74LS08 pin 12 (A4)||MN4146P pin 10 (A5)|
|74LS08 pin 11 (Y4)||MN4164P pin 11 (A4)|
|74LS08 pin 10 (B3)||MN4164P pin 12 (A3)|
Connection diagram of the 74LS08:
Connection diagram of the 74LS136: