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.
tofro wrote: Wed Feb 26, 2025 8:24 amMost 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.
Hi & Welcome!
I am interested about your QL RAM expansion,
please, Could you give me information about it?
Recently I have reprogramed the famous algorithm to detect faulty ICs in QL with similar RAM expansions like yours. So I would like to know if also It would work fine with my modification.
Where is the glue logic that allows to access to higher RAM positions than 40000h?
Or how that works?
Thank you
Note: About the internal RAM expansion that I have seen by now are based on an external glue logic that very often is settled north the CPU, as I show in my Github: https://github.com/Silveriomrs/Minerva_RAM_Test
Last edited by Popopo on Wed Apr 30, 2025 2:40 pm, edited 1 time in total.
ql_freak wrote: Tue Feb 25, 2025 11:01 pm
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 have seen two different recently, the Danish one with 512KB and another (Don't know from where) with 640KB using extra IC in piggyback.
Second option more annoying to work or repairing matters.
I am looking for more documentation of them to add it to my Github.
Do you know more details?
Thanks
janbredenbeek wrote: Thu Feb 27, 2025 11:16 pm
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.
??? what what what??? how interesting!!!
Please, do you have photos or extra information about it?
Thanks
janbredenbeek wrote: Thu Feb 27, 2025 11:16 pm
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.
??? what what what??? how interesting!!!
Please, do you have photos or extra information about it?
Thanks
I think I had the same - They were sold through the German Vobis chain BITD and relatively common. Unfortunately, the thing has long gone and no photos exist.
tofro wrote: Wed Apr 30, 2025 6:11 pm
I think I had the same - They were sold through the German Vobis chain BITD and relatively common. Unfortunately, the thing has long gone and no photos exist.
Such a pity!
Depending on how they were integrated I could modify the code of the RAM Fail Test to also include this kind of updates.
Thanks for the extra information tofro!
