QL internal 27C512 ROM adapter board
Posted: Wed Feb 26, 2025 1:07 pm
I'm in the process of bringing my old QLs to life again. I got three of them and each has a different ROM. I've got a JM, a JS and an AH ROM in a ceramic package with a "golden" cover! One of them is an issue 6, the other two an issue 5.
So I thought the best thing to do was to upgrade all of them to the latest Minerva ROM. or are there better solutions?
But I couldn't find a proper PCB for a standard 27C512, so I made one myself. Just quick and dirty. No fancy ROM switching. It has a decoder that only decodes #CE on accesses to the first 48K, so the external ROM port doesn't clash with the internal ROM. I found a mICE, plugged it in and everything seems to work just fine! No magic smoke..!
With the new Minerva ROM I can finally see that my FrankenQL is working.
(viewtopic.php?t=2624&hilit=82s123)
It reports 128K or 512K depending on a switch that is located at the rear of the QL. I bought this QL decades ago and the previous owner did the mod.
But oddly enough, this QL has been running with a Trump card with the full 896K of RAM with the switch in the 512K setting! I can only tell the difference with the Trump card unplugged. With the Trump card fitted it reports 896K regardless of the switch state. So with the internal RAM mod, I guess my RAM is double buffered 
Anyway... To make a long story short, I have a few PCBs left, because I only need 3 or 4 of them. If anyone is interested, let me know. I can put them on www.sellmyretro.com.
I have a few 27C512s, so I can burn the ROM of your choice.
So I thought the best thing to do was to upgrade all of them to the latest Minerva ROM. or are there better solutions?
But I couldn't find a proper PCB for a standard 27C512, so I made one myself. Just quick and dirty. No fancy ROM switching. It has a decoder that only decodes #CE on accesses to the first 48K, so the external ROM port doesn't clash with the internal ROM. I found a mICE, plugged it in and everything seems to work just fine! No magic smoke..!
(viewtopic.php?t=2624&hilit=82s123)
It reports 128K or 512K depending on a switch that is located at the rear of the QL. I bought this QL decades ago and the previous owner did the mod.
- FrankenQL
Anyway... To make a long story short, I have a few PCBs left, because I only need 3 or 4 of them. If anyone is interested, let me know. I can put them on www.sellmyretro.com.
I have a few 27C512s, so I can burn the ROM of your choice.