Search found 25 matches

by protek
Tue May 26, 2020 5:19 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Well, no luck with the 150 ns Fujitsus either. One thing I should mention is that, what looks like a cursor, appears to be blinking maybe a 10 seconds from boot-up, before it freezes.

Otherwise, I’m really running out of ideas.
by protek
Sun May 24, 2020 5:55 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

I’m still waiting for the new RAM chips to arrive, but I should be getting them tomorrow or the day after. I really hope the new RAM will solve the issue, because I really don’t know what else to try.
by protek
Sun May 10, 2020 8:38 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Wow, you’ve really done an amazing job deciphering the inner workings of the ULA, Mike! Yeah, my el cheapo oscilloscope is hardly up to the task. It doesn’t even come with a proper probe. Anyhow, I went and ordered a set of Fujitsu 8264 150 ns RAMs. I guess I just want to rule out that it isn’t the ...
by protek
Fri May 08, 2020 6:18 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

I just realized that the garbled screen is trying to tell the amount of free ram too.

J. M[ NZMM
BYTES FREE
by protek
Fri May 08, 2020 5:36 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Swapping IC 15/16 over, and no change to the character? I was expecting the character to change if the DRAM was marginal (problem moves with the chip). So there is still something odd about data line D3, causing trouble on the ULA's first read attempt. Would an oscilloscope shed more light into thi...
by protek
Thu May 07, 2020 9:09 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

^Hahah, yes, 150 ns. Silly me. :lol: I just might get the IC20 changed and socketed. It should probably be an easier job than the hex inverter was as I cleaned my desoldering gun of the clog. Nevertheless, it might be too tight a spot to use my preferred method, combination of desoldering gun and a ...
by protek
Thu May 07, 2020 6:06 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

I tried swapping the IC15 and IC16. I’m still getting the ’(’ character. One thing I should mention. It looks like the cursor is blinking on the row just above the ’Zmil’, roughly in the center of the screen. This was even before the RAM swap. I don’t know if it actually is the cursor, since typing ...
by protek
Thu May 07, 2020 8:30 am
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Okay, this is a bit perplexing. I look at the schematics and see that D3 that is pin12 on the ULA should be connected to IC16. But when I use my multimeter to check the continuity, the pin12 beeps with IC17 data lines. IC16 data lines beep with pin 13 on the ULA and pin 29 on the CPU and VIA. I supp...
by protek
Thu May 07, 2020 6:10 am
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

I checked the continuities between your suggeste pins, and indeed there’s no continuity at all between ULA pin 12 and IC16 pins 2 qnd 14 leg pins. CPU and VIA have continuity with the ULA. I did a quick visual inspection on the socket pin solder joints. The pin 14 joint on IC16 looks a bit dodgy, so...
by protek
Thu May 07, 2020 4:49 am
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Wow, Mike, that is indeed mindblowing! Thanks! I’ll be checking the continuities later today. As for the keyboard, I actually tried typing those commands but the keyboard isn’t very responsive. I’m able to type in maybe one or two keypresses as I suspect from the audible response I’m getting but the...
by protek
Wed May 06, 2020 7:34 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Unfortunately, I don’t have an oscilloscope, just a logic probe. I’ll try the other pin on the ULA. RAS and CAS pins did give a pulse on my probe when I tried it. Well, the hex inverter wasn’t the problem, or then I have two duff hex inverters. At least, I now have a socket for the inverter. It was ...
by protek
Wed May 06, 2020 12:26 pm
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

I consulted the manual, and I’m not getting what I interpret to be a clock signal on the ULA pin 7. The probe is just faintly high. Is the hex inverter the culprit?
by protek
Wed May 06, 2020 11:47 am
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Image
Here is how the screen looks with MikeB’s ROM and 4164 chips. There’s a repeating pattern clearly. Also a constant tone is played out of the speaker.
by protek
Wed May 06, 2020 10:36 am
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Image

Here’s how the screen looks like with the 4164 RAMs, btw. The b/w bars are different.
by protek
Wed May 06, 2020 9:41 am
Forum: Technical questions
Topic: Help with two Orics
Replies: 41
Views: 6536

Re: Help with two Orics

Yeah, gotta try to source some faster ones or see if I can get lucky with the 4164s that I have.

I only tried iss’s diagnostic ROM. I should probably try Mike’s ROM too.