News:

Printed Amstrad Addict magazine announced, check it out here!

Main Menu
avatar_Chinnery

How to read a Basic Rom

Started by Chinnery, 17:11, 10 January 18

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Chinnery


I know there are many dumps of the basic rom 40009 from the Amstrad 464, but I've just got hold of a rom reader/burner and thought I would have a go at dumping it for myself, my ultimate goal burning a dual basic rom (v1.0 and v1.1)
If I try read the 40009 rom (I set my reader up to read 27x128), I get a bunch of FF's... However, if I try read the 40025 from my 6128, I get a valid reading, comparing with the rom included with Winape.
I guess I'm doing something wrong as usual, but can't figure out what.
And when I eventually get round to burning my dual-basic rom, would a UPD27C256AC-15 be suitable? I would expect to raise pin27 to 5v to get the upper half of the rom, and ground it to 0v to get the lower.

GUNHED

IIRC the main ROM in the 6128 contains BASIC and CPC-OS (=Firmware) in one 32 KB ROM.


Try to read a 32 KB ROM type.


Else you can use MAXAM to copy any ROM to the RAM and subsequently write it to disc.

http://futureos.de --> Get the revolutionary FutureOS (Update: 2023.11.30)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

Bryce

Are you sure you didn't fry the 40009 while removing it?

If there is still some residual solder on the pins they may not all be making good contact with the EPROM reader ZIF socket. Try inserting the 40009 into an IC socket first and then the socket pins into the EPROM reader.

And set your EPROM reader to 27x256, otherwise you are only reading half of the ROM.

Bryce.

Chinnery

Quote from: Bryce on 19:32, 10 January 18
Are you sure you didn't fry the 40009 while removing it?

Perfectly sure. It was socketed, like all the RAM chips. I will bob it back in and see if it still works though as a second test.


It is something I'd noticed later that the roms are 32k. I'd just checked in Winape and seen them as 16k. I didn't know they contained the firmware too. I'm going to redump as 32k roms later on, see if that makes any difference to the output.


What would be the conequence of placing a 40025 rom in place of the 40009 as a direct replacement. Is the firmware going to get confused with the hardware available?


Bryce

No problem at all. As long as the Firmware version matches the BASIC version it will work. BASIC 1.0 won't work with the 6128 Firmware and BASIC 1.1 won't work with the 464 Firmware, but if the firmware / BASIC are matched it will work in both. The mismatch doesn't work because the locations of firmware routines were changed in the 6128, not because of any hardware differences.

Bryce.

Powered by SMFPacks Menu Editor Mod