Search found 577 matches

by iss
Sat Apr 21, 2018 1:07 pm
Forum: Technical questions
Topic: oric atmos boot stuck at AA pattern
Replies: 14
Views: 328

Re: oric atmos boot stuck at AA pattern

Nice work, seb! About the R0* in my old post - it depends on amplification of the particular chosen transistor - it should be in range 200 Ohms ... 2kOhms, or maybe even more. It's not danger to experiment with any R value, the best is to use 10k trimmer and adjust the picture. I think you can get b...
by iss
Fri Apr 20, 2018 11:11 pm
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 20
Views: 1107

Re: FastBoot/FastLoad on Pravetz 8D/Disk II

Well, I finished the new controller and I'm very happy to say it works perfect! On the right is old broken one FDC, on the left - the new beast (still with trimmers for fine adjusting of the MAP signal), 20180421_000450.jpg And here is my version of the slideshow "as is" running on real hardware: :s...
by iss
Fri Apr 20, 2018 10:48 pm
Forum: Tape and floppy disk converters
Topic: FloppyBuilder evolution
Replies: 89
Views: 30771

Re: FloppyBuilder evolution

I'm advancing slowly in FloppyBuilder for 8D-FDC hardware. Here you can see optimized version of my test demo from previous post running on real 8D FDC. It's faster than in Oricutron :). [media]https://youtu.be/Vs5_dNjJal0[/media] I'll make some code cleanup and will post sources and all technical d...
by iss
Tue Apr 17, 2018 10:33 pm
Forum: Technical questions
Topic: Microdisc connectors
Replies: 9
Views: 499

Re: Microdisc connectors

Generally powering trough expansion slot is not wrong and it 'highly likely' ;) will work always. Although for me it's not good practice for very simple reason - the purpose of ribbon cables (and connectors) are to be signal cables i.e. for low currents (for instance about 100mA) where Oric wants >6...
by iss
Tue Apr 17, 2018 10:15 pm
Forum: Technical questions
Topic: oric atmos boot stuck at AA pattern
Replies: 14
Views: 328

Re: oric atmos boot stuck at AA pattern

+1 for diagnostic ROM else the usual suspects are RAM chips - btw, very interesting rare chips Inmos Ims2600.
Do you have any modifications on back of the PCB? And one easy thing: check if the NMI button works i.e. its contacts are not permanently connected.
by iss
Tue Apr 17, 2018 9:49 pm
Forum: Technical questions
Topic: Microdisc connectors
Replies: 9
Views: 499

Re: Microdisc connectors

And about the PSU. Here is one broken original Microdisc PSU - the plastic insulation is so old that it's not 'plastic' anymore. It waits silently its turn to be repaired one day... :) 1.jpg 2.jpg But more interesting here is the schematic (sorry for the ugly drawing): 3.jpg Important thing is that ...
by iss
Tue Apr 17, 2018 9:29 pm
Forum: Technical questions
Topic: Microdisc connectors
Replies: 9
Views: 499

Re: Microdisc connectors

As to powering the Oric, normally this is done directly from the Microdisc through the ribbon cable to the Oric... I think normally you can't power Oric with the ribbon cable. This is original Microdisc controller - pin 33 on the ribbon connector is not connected to +5V track. Yes, it looks like it...
by iss
Wed Apr 11, 2018 8:19 pm
Forum: Technical questions
Topic: Microdisc connectors
Replies: 9
Views: 499

Re: Microdisc connectors

Reference to Microdisc connectors here and here (China 10 pcs cheep but long waiting) and an eBay search . Maybe you can find them somewhere closer to your place. About the power supply - I suppose you have a PC PSU - if so DON'T USE the 12V to power Oric together with Microdisc and floppies - there...
by iss
Sun Apr 08, 2018 3:32 pm
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 20
Views: 1107

Re: FastBoot/FastLoad on Pravetz 8D/Disk II

Great sources! :)
One VIA specific thing: the value for timers must be '-2' for precise timings, i.e. #4FBA-2=#4FB8.
And this 1.0205 Mhz - I think it's apple][ clock, for Oric in my opinion it need to be exactly 1.0 MHz.
by iss
Sun Apr 08, 2018 11:08 am
Forum: Tape and floppy disk converters
Topic: Experimental very fast tape loading
Replies: 88
Views: 9107

Re: Experimental very fast tape loading

Yep, Symoon you are right.
RTI retrieves the Processor Status Word (flags) and the Program Counter from the stack in that order (interrupts push the PC first and then the PSW).
Note that unlike RTS, the return address on the stack is the actual address rather than the address-1.
by iss
Sun Apr 08, 2018 10:48 am
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 20
Views: 1107

Re: FastBoot/FastLoad on Pravetz 8D/Disk II

In my opinion it's worth, because it's not marginal but "boutique stuff". ;)

EDIT: I'm starting to de-marginalize 8D hardware - with new one the number of users will be increased by 100% :D.
20180408_155723.jpg
by iss
Sun Apr 08, 2018 10:21 am
Forum: Tape and floppy disk converters
Topic: Experimental very fast tape loading
Replies: 88
Views: 9107

Re: Experimental very fast tape loading

My proposal is modest but I think it makes sense - in short you don't need PHP/RTI in the interrupt routine. Use only RTS instead - gain 3 cycles and 1 precious byte. :) I.e. from: 04CD 4 AE 00 03 LDX $0300 Re-initialize CB1 flag 04D0 4 AE 08 03 LDX $0308 Read duration in X 04D3 4 8E 09 03 STX $0309...
by iss
Sat Apr 07, 2018 11:20 pm
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 20
Views: 1107

Re: FastBoot/FastLoad on Pravetz 8D/Disk II

About the 'linear' loading here is what happens: when picture loop starts fastloader reads sectors: 09,0a,0b,0c,...,07,08... and so on until re-seek to track 1, on the second loop sectors are read: 0a,0b,0c,0d,....,07,08,09... then seek again to track 1, and yes, you guess it :) : 0b,0c,...,08,09,0a...
by iss
Sat Apr 07, 2018 8:22 pm
Forum: Operating systems
Topic: FastBoot/FastLoad on Pravetz 8D/Disk II
Replies: 20
Views: 1107

Re: FastBoot/FastLoad on Pravetz 8D/Disk II

Scalex, you are really good how you found this nice little trick! Respect! I've got the idea for RTS at $B800 like an "illumination" ;) trying to optimize the code size for FloppyBuilder, where one single sector have to contain boot code for Jasmin and for 8D. I'm sorry that I simply forgot to uploa...
by iss
Sat Apr 07, 2018 7:58 pm
Forum: Tape and floppy disk converters
Topic: Experimental very fast tape loading
Replies: 88
Views: 9107

Re: Experimental very fast tape loading

Congrats for victory, Symoon!
Your source looks super, I tried to tested it with some quickly written encoding code based on explanations in your file but failed. Anyway, my tests are not relevant and only for fun, I'll wait until you release the encoding part.