Search found 179 matches

by Brane2
Mon May 19, 2014 3:06 pm
Forum: Hardware
Topic: Battery connection points on a qimi ??
Replies: 13
Views: 4314

Re: Battery connection points on a qimi ??

If you are going to use NiMh, go for LSD ( Low Self Discharge) ones. Difference can be drastic. I've bought a few tens of cheap LSD cells in Lidl for €1 per AA/AAA ( €4 per 4-pack) and even those rock. They claim IIRC 85% charge retention after a year. I've tried them in wall clocks, small shaver th...
by Brane2
Sat May 17, 2014 11:16 am
Forum: Hardware
Topic: DIY RAM EXPANSION
Replies: 93
Views: 18227

Re: DIY RAM EXPANSION

green screen is OK-ish, I guess...

You can always use it for movie special effects and post-production... :mrgreen:
by Brane2
Thu May 15, 2014 7:24 pm
Forum: Hardware
Topic: Ser1 - Ser2 fault
Replies: 2
Views: 811

Re: Ser1 - Ser2 fault

Try reseating IPC and ULA2, check SER connectors for oxidation if you have those non-standard ones, check voltages on drivers ( you need +/-12V IIRC).
by Brane2
Wed Apr 30, 2014 10:38 am
Forum: Hardware
Topic: ULA1 60Hz video - how much can I lift the clock ?
Replies: 10
Views: 2790

Re: ULA1 60Hz video - how much can I lift the clock ?

Interesting.

Which ULAs do you have ?

Two of mine are:

1. Ceramic
1.row: PS P 02
2.row CLA2310
3.row: YB413A

2. Plastic
1. row: PS P B
2. row: CLA2310
3.row: YB453E
by Brane2
Mon Apr 28, 2014 12:54 pm
Forum: Hardware
Topic: ULA1 60Hz video - how much can I lift the clock ?
Replies: 10
Views: 2790

Re: ULA1 60Hz video - how much can I lift the clock ?

The JSU rom controls the display depth through bit 6 of the master chip register at $18063 (0=625, 1=525 line). Yeah. Thanks. I'll have to try that right now... But before that I'll have to train small PIC to count all that CLK, HSYN and VSYN timings. And to send them through the COMport to PC... :D
by Brane2
Thu Apr 17, 2014 5:27 am
Forum: Hardware
Topic: has anyone tried reversing polarity on microdrive motor ?
Replies: 4
Views: 866

Re: has anyone tried reversing polarity on microdrive motor

Don't think of it as the tape being pushed to the outside of the loop - always think of it as the tape being pulled from the inside of the loop... The (dumb) idea was not to push the tape but to wait for it to be pulled from the other end. I thought that there is maybe 5-10 cm of extra length that ...
by Brane2
Thu Apr 17, 2014 5:25 am
Forum: Hardware
Topic: has anyone tried reversing polarity on microdrive motor ?
Replies: 4
Views: 866

Re: has anyone tried reversing polarity on microdrive motor

Errm, forget that. I've just tried it and got my answer soon enough. Dumb idea in the first place, but I thought if tape is tense enough that I could force it to go another direction even if for limited length. I reversed polarity on one drive I had laying around and apllied small voltage, so that i...
by Brane2
Thu Apr 17, 2014 5:07 am
Forum: Hardware
Topic: has anyone tried reversing polarity on microdrive motor ?
Replies: 4
Views: 866

has anyone tried reversing polarity on microdrive motor ?

I know that it is designed to work in one direction.

But in practice, could the tape be played backwards or at least reversed, so that one wouldn't need extra 7s for next pass for a sector that has just passed the head...
by Brane2
Wed Apr 16, 2014 12:18 pm
Forum: Hardware
Topic: Q: ZX8301 effect on memory bandwidth?
Replies: 21
Views: 4713

Re: Q: ZX8301 effect on memory bandwidth?

Yes, if you have fast logic. With bare transitors that you have to wire and bunch together within ULA i think it might be tricikier. Even more so that the final result is kosher ( equal pixel lengths etc)...
by Brane2
Wed Apr 16, 2014 12:35 am
Forum: Hardware
Topic: Q: ZX8301 effect on memory bandwidth?
Replies: 21
Views: 4713

Re: Q: ZX8301 effect on memory bandwidth?

An interesting tidbit of information: there is a blanking bit in the 8301 screen control register, but the system continues reading screen data even when the screen is blanked. Somewhat OT, but a few other intersting things: At 15MHz, PAL horizontal line takes 960 cycles. And visible part seems to ...

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