Amiga 2000 - Rev 6.2 has less onboard ram than preceeding boards?

[Retrogradient]

This has confused me quite a bit.



The RAM on the board is the TMS4256-15NL


The Rev. 6.2 boards have 8 of these chips, but the previous boards (Rev 4.x for example) have 32 of these chips.




Whats up with that?


Thank you...

[pipper]

Technological advances. More Storage per Chip.

[Retrogradient]

but its the same chip, and same storage capacity (256kb)...

[Thomas Richter]

Originally Posted by Retrogradient

The RAM on the board is the TMS4256-15NL

This is a 265Kx1 RAM chip found on the Rev.4 boards.

Originally Posted by Retrogradient

The Rev. 6.2 boards have 8 of these chips...

Actually, the Rev 6.2 boards have 256Kx4 chips, for example TMS44C256-15. Note the additional 4C in its label indicating that it stores 4 bits per cell.

[jasonsbeer]

Originally Posted by Thomas Richter

Actually, the Rev 6.2 boards have 256Kx4 chips, for example TMS44C256-15. Note the additional 4C in its label indicating that it stores 4 bits per cell.

This. The part numbers can be confusing, but Rev 5 and up all used 256k x 4 DRAM. Earlier revisions all used 256k x 1.

[Retrogradient]

I was reading about replacement parts on Rev 6.2 (More specifically referencing the Bill of Materials for a replica rebuild) and it called for 4256-10NL parts

539 U501 4256-10 Top Memory chip
540 U502 4256-10 Top Memory chip
541 U503 4256-10 Top Memory chip
542 U504 4256-10 Top Memory chip
543 U505 4256-10 Top Memory chip
544 U506 4256-10 Top Memory chip
545 U507 4256-10 Top Memory chip
546 U508 4256-10 Top Memory chip

Considering the replica boards are Rev 6.2...

Shouldn't these be 44C256-15 / 44C256-10 than ???

[jasonsbeer]

Originally Posted by Retrogradient

I was reading about replacement parts on Rev 6.2 (More specifically referencing the Bill of Materials for a replica rebuild) and it called for 4256-10NL parts

539 U501 4256-10 Top Memory chip
540 U502 4256-10 Top Memory chip
541 U503 4256-10 Top Memory chip
542 U504 4256-10 Top Memory chip
543 U505 4256-10 Top Memory chip
544 U506 4256-10 Top Memory chip
545 U507 4256-10 Top Memory chip
546 U508 4256-10 Top Memory chip

Considering the replica boards are Rev 6.2...

Shouldn't these be 44C256-15 / 44C256-10 than ???

Maybe. Depends on the manufacturer. Many (not all) manufacturers designate their 256k x 4 DRAM with a part number containing or ending with 4256-xx. Where the xx is the speed of the DRAM. The bill of materials is simply telling you to look for 4256-10 in the part number. However, it does not have to be -10. The Amiga 2000 Rev 6 specs call for 150ns (-15) or faster. I have been using 70ns DRAMS (-70) to replace the stock ones when needed.

See this link for some compatible DRAM options. http://www.amiga-stuff.com/hardware/256kx4-dram.html

[Retrogradient]

Originally Posted by jasonsbeer

Maybe. Depends on the manufacturer. Many (not all) manufacturers designate their 256k x 4 DRAM with a part number containing or ending with 4256-xx. Where the xx is the speed of the DRAM. The bill of materials is simply telling you to look for 4256-10 in the part number. However, it does not have to be -10. The Amiga 2000 Rev 6 specs call for 150ns (-15) or faster. I have been using 70ns DRAMS (-70) to replace the stock ones when needed.

See this link for some compatible DRAM options. http://www.amiga-stuff.com/hardware/256kx4-dram.html

thanks for the information.

I have been really considering this project of getting a replica board, as the Amiga I bought was quite damaged, and am rather keen on getting it up and going.


These rams in north America look pretty pricey and sparse though.
Thanks.