The Sinclair QL Forum

Posted: **Thu Feb 27, 2025 11:16 pm**

ql_freak wrote: Tue Feb 25, 2025 11:01 pm Welcome!

Sure you have a 640 K internal memory epansion!

I have never heard of it. Internal memory expansion normally had a total of 512 KByte (and you have to send it to a company which fitted the upgrade). Disadvantage: It was slow memory, cause also the video hardware ("processor") accessed it and hat to share time with the CPU.

I used to have a similar expansion from MicroPeripherals, but it was 256K (total 384K) so it probably had only 8 RAM chips on board. Also, it didn't require soldering.
It did have the memory contention drawback.

Posted: **Fri Mar 07, 2025 7:34 pm**

tofro wrote: Wed Feb 26, 2025 8:24 am Most of the internal expansions hat that downside, but definitely not all of them. Internal doesn't automatically mean contended.

It depends more or less on whether DRAM or SRAM was/is used. As far as I know, internal DRAM expansions never came with separate controller for refresh, but used the QL ULA for that purpose, so they all suffered. SRAM expansions were/are fine.

Posted: **Fri Mar 07, 2025 8:58 pm**

Hi,

see the QL WIKI: https://wiki.theqlforum.com/doku.php?id ... ry_upgrade

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