exxos wrote: 28 Sep 2018 08:20
you lift the MMU end up of those resistors and then tie the free ends to 5V.
and
rubber_jonnie wrote: 28 Sep 2018 08:22
If I recall, if you are leaving the RAM chips in, you'll need to de-solder the bottom end of those 3 resistors and connect them to +5v to disable that second bank of 512KB RAM, a bit like if you added a Marpet or similar RAM add on.
Double check this before you do it though in case I'm remembering it wrong.
I think the double check was done for me already ;-)
sandord wrote: 28 Sep 2018 14:15
I think the double check was done for me already ;-)
Yeah, I reckon so :)
I think we wrote our replies at almost the same time.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
It's running with 512kb right now, so far I don't see any problems.
I guess the only practical way of fixing this ST (besides leaving it crippled with 512kb) is upgrading it with a RAM kit.
Replacing the darn j-leaded RAM chips looks pretty much impossible to me.
- with 1mb, I get rogue pixels GemBench at the bottom of the screen
(video address is near the top end of the RAM)
- with 1mb, I get rogue pixels in Metrocross at the bottom of the screen
(not sure where the video address is in this game)
- with 512kb, I get rogue pixels in GemBench at the bottom of the screen
(video address is near the top end of the RAM)
- with 512kb, I get rogue pixels in Metrocross
(not sure where the video address is in this game)
- I've seen YAART detect a memory error only once out of quite a few runs.
- With 1mb, I've seen YAART show rogue pixels in between the status text quite a lot but it never detected a memory error. Looks like YAART doesn't test the RAM where the status text is rendered to?
Looks like a pattern to me, problems appear to be at the end of each bank only. Too much of a coincidence?
