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Forum: Retrogaming General Discussion 11 February 2019, 12:45
Replies: 147
Views: 7,963
Posted By pandy71
Well... from my perspective he is passionate,...

Well... from my perspective he is passionate, determined and wiling to do research - classical example is color reduction to efficiently use CLUT machines limitation (valid for Amiga and Atari ST) -...
Forum: Retrogaming General Discussion 10 February 2019, 14:32
Replies: 147
Views: 7,963
Posted By pandy71
After brief source check, Paula emulation is done...

After brief source check, Paula emulation is done with fixed frequency (obvious as STE do not support variable sample rate as Paula) - and this means that anything sampled faster than 25033Hz will be...
Forum: support.Hardware 02 February 2019, 02:03
Replies: 9
Views: 445
Posted By pandy71
You can use this method - i strongly disagree...

You can use this method - i strongly disagree with their approach to PCB tin plating but this method will work nicely for rusty Amiga shield - remove rust mechanically to clean metal (sanding paper?...
Forum: support.Hardware 02 February 2019, 01:52
Replies: 2
Views: 221
Posted By pandy71
Ages ago i've used styrofoam and aluminium foil...

Ages ago i've used styrofoam and aluminium foil to store IC's. It works fine. Cons may be way lower impedance - at some point this may be issue for charged capacitors - by connecting with foil large...
Forum: Retrogaming General Discussion 02 February 2019, 01:43
Replies: 147
Views: 7,963
Posted By pandy71
Don't get me wrong but i see no problem to...

Don't get me wrong but i see no problem to convert signed to unsigned and vice versa - important is quantization steps and seem curve is correct - higher level less accurate (bigger) quantization...
Forum: Retrogaming General Discussion 29 January 2019, 21:44
Replies: 147
Views: 7,963
Posted By pandy71
Well... it looks to me quite OK - similar...

Well... it looks to me quite OK - similar characteristics are common for example ulaw/Alaw https://en.wikipedia.org/wiki/%CE%9C-law_algorithm
Main difference is insufficient bit resolution (4 or 5)...
Forum: Amiga scene 16 January 2019, 15:23
Replies: 90
Views: 8,620
Posted By pandy71
Nice art but i realised that all files are jpg...

Nice art but i realised that all files are jpg and they are affected by jpg artifacts (https://en.wikipedia.org/wiki/Gibbs_phenomenon) - it is better to use png or gif instead jpg for pixel art...
Forum: Retrogaming General Discussion 16 January 2019, 14:46
Replies: 147
Views: 7,963
Posted By pandy71
Atari ST use YM2149 which is enhanced version of...

Atari ST use YM2149 which is enhanced version of AY-3-8910 - so AY-3-8910 is worse than YM2149. Audio quality difference is meaningless and enhancements are mostly functional type.

Comparing with...
Forum: Retrogaming General Discussion 15 January 2019, 21:52
Replies: 147
Views: 7,963
Posted By pandy71
Depends, signal volume/envelope control in AY is...

Depends, signal volume/envelope control in AY is 4 bit (non linear - approx logarithmic), SID and POKEY are 4 bit linear AFAIR, ST YM is 5 bit (significant difference from AY). So noisy (high...
Forum: Retrogaming General Discussion 14 January 2019, 12:58
Replies: 147
Views: 7,963
Posted By pandy71
I expressed this earlier - compare comparable,...

I expressed this earlier - compare comparable, trying to compare incomparable things you need to be very careful and use values in proper context - i don't judge POKEY quality, also don't judge AY...
Forum: Retrogaming General Discussion 14 January 2019, 03:41
Replies: 147
Views: 7,963
Posted By pandy71
Then even Intel 8253 can be considered as...

Then even Intel 8253 can be considered as "GENERAL PURPOSE sound chip"...
Forum: Retrogaming General Discussion 10 January 2019, 18:12
Replies: 147
Views: 7,963
Posted By pandy71
Well, DSD use 2.8224MHz 1-bit to be High End...

Well, DSD use 2.8224MHz 1-bit to be High End audio source (120dBFS).
So i estimate that difference between 985kHz and 3.58MHz is around 50dB
Are you able to hear difference between 7 and 16 bits?
...
Forum: Retrogaming General Discussion 10 January 2019, 02:56
Replies: 147
Views: 7,963
Posted By pandy71
What a bizarre thread... Atari (ST) had chance to...

What a bizarre thread... Atari (ST) had chance to deliver decent audio chip - it was called "AMY 1" (https://en.wikipedia.org/wiki/Atari_AMY) and can do something like IFFT (additive synthesis) - but...
Forum: Hardware mods 06 July 2018, 18:18
Replies: 28
Views: 2,405
Posted By pandy71
Excuse late reply - as i said earlier - other...

Excuse late reply - as i said earlier - other activities has higher priority and also as i said earlier - if i can help then i will be happy to help.
If you face any problem then you should share...
Forum: Hardware mods 03 July 2018, 12:27
Replies: 28
Views: 2,405
Posted By pandy71
Doing some things on this area but decided to not...

Doing some things on this area but decided to not say anything until it will be ready.
Progress is slow due other things with higher priority.



I need to finish other things first so decided...
Forum: Hardware mods 03 July 2018, 12:23
Replies: 6
Views: 786
Posted By pandy71
Nope - there can be more than 1.5MB slow, and...

Nope - there can be more than 1.5MB slow, and over 1.5MB in other areas normally not used (depends on machine and used extensions).
And 68K allow to address 4x 16MiB (program and data for user and...
Forum: support.Hardware 03 July 2018, 12:17
Replies: 5
Views: 372
Posted By pandy71
Use A520 schematics (...

Use A520 schematics ( http://members.iinet.net.au/~davem2/overclock/A520.html ) and MC1377 datasheet - or replace PCB with something more modern.
Forum: support.Hardware 03 July 2018, 12:12
Replies: 10
Views: 537
Posted By pandy71
You didn't fixed issue - you only replaced some...

You didn't fixed issue - you only replaced some parts that was corrupted as outcome of the issue itself - short way to repeating damages. Use service manual and/or datasheet for part - disconnect...
Forum: Hardware mods 03 July 2018, 01:38
Replies: 28
Views: 2,405
Posted By pandy71
I see - then OK. Check page 10 - video...

I see - then OK.



Check page 10 - video clocks and phase relations between them.
Forum: Hardware mods 02 July 2018, 23:20
Replies: 28
Views: 2,405
Posted By pandy71
It can be different phase - you should check...

It can be different phase - you should check Gayle datasheet - there is waveforms provided to show all dependencies. Side to this my assumption is that you using video port not hooking wires to pins...
Forum: support.Hardware 02 July 2018, 18:49
Replies: 10
Views: 537
Posted By pandy71
You should check oscilograms (waveforms diagrams...

You should check oscilograms (waveforms diagrams in technical spec) especially on horizontal deflection - as 1084 is made similar to small (14 inch) TV then flyback may be shared with PSU.
Forum: Hardware mods 02 July 2018, 18:42
Replies: 6
Views: 786
Posted By pandy71
idrougge is right - easily can't be done but... ...

idrougge is right - easily can't be done but...

...but you could modify autoconfig and add chips on top (piggyback), modify address selection (so efficiently building new expansion) to fit some...
Forum: Hardware mods 02 July 2018, 18:22
Replies: 28
Views: 2,405
Posted By pandy71
Yes, Agnus is address generator (it produce...

Yes, Agnus is address generator (it produce address but data going to Denise), you can manually (CPU and/or Copper) feed data to BPLxDAT registers (search for thread related to HAM with less than 6...
Forum: Hardware mods 02 July 2018, 11:16
Replies: 28
Views: 2,405
Posted By pandy71
RGA is internal (chipset) address bus, data are...

RGA is internal (chipset) address bus, data are transferred over shared data bus (shared with CPU). Denise is triggered by Agnus (usually) - some access to RGA works as strobe (so Denise internal...
Forum: support.Hardware 30 June 2018, 14:47
Replies: 41
Views: 2,027
Posted By pandy71
I use something like this:...

I use something like this: https://www.newegg.com/Product/Product.aspx?Item=N82E16817103066 - same form factor is present in many rack mountable blade servers (frequently available for bargain price...
Forum: Hardware mods 30 June 2018, 14:37
Replies: 28
Views: 2,405
Posted By pandy71
Of course - every timing in system will be...

Of course - every timing in system will be different - audio, UART, FDD - not sure how much original chipset can be overclocked - in past i think i was successful to replace original generator with...
Forum: Amiga scene 30 June 2018, 13:23
Replies: 37
Views: 2,065
Posted By pandy71
Thx Toni, so eventually list (of DMAC's used in...

Thx Toni, so eventually list (of DMAC's used in Amiga designs) will be quite short - MC68440* (and similar DMAC from Motorola e.g. 68450, AFAIR it was also 68850 DMAC [not MMU 851] but seem it is...
Forum: Hardware mods 30 June 2018, 12:38
Replies: 28
Views: 2,405
Posted By pandy71
few words from me too. To simplify your design...

few words from me too.
To simplify your design (and make it more robust i.e. higher chance to success) you can generate own pixel clock (you can use programmable generator such Si5351 - it is quite...
Forum: Amiga scene 30 June 2018, 12:15
Replies: 37
Views: 2,065
Posted By pandy71
Yes, indeed, NCR53C710 has implemented MC68K bus...

Yes, indeed, NCR53C710 has implemented MC68K bus timing and logic. So this may explain a lot - if there is DMA on SCSI then or it will use DMAC or SuperDMAC from Commodore, or GVP or NCR chip with...
Forum: Amiga scene 29 June 2018, 18:38
Replies: 37
Views: 2,065
Posted By pandy71
Common but only amongst few main vendors capable...

Common but only amongst few main vendors capable to pay for ASIC or CPLD. There was no cheap DMA controller on MC68k market - 68440 or 68450 was quite expensive and uncommon out of VME world. Some of...
Forum: Amiga scene 28 June 2018, 23:51
Replies: 37
Views: 2,065
Posted By pandy71
Only few SCSI controllers on Amiga use DMA and...

Only few SCSI controllers on Amiga use DMA and then they usually use DMAC from Commodore with DMAC limitations (like 24 bit address bus) - not sure why such approach - perhaps general assumption was...
Forum: Amiga scene 28 June 2018, 20:15
Replies: 37
Views: 2,065
Posted By pandy71
Why "it is too late"? Should be not a big issue...

Why "it is too late"? Should be not a big issue to create DMA controller and implement DMA for PATA. Low speed is outcome of overall available bandwidth within Amiga SoC. Also instead creating HW DMA...
Forum: Amiga scene 28 June 2018, 03:12
Replies: 14
Views: 1,730
Posted By pandy71
As mentioned YUV generation was easier than RGB...

As mentioned YUV generation was easier than RGB and supported by many computers - YUV was easy to generate as it can be created purely in digital domain in simple circuits (as colour information is...
Forum: Amiga scene 28 June 2018, 02:58
Replies: 37
Views: 2,065
Posted By pandy71
Hope you are aware that SATA is fast serial...

Hope you are aware that SATA is fast serial interface (point to point, differential, low voltage multi Gigabit per second) and there is no easy way to interface SATA with old 5V logic. You can use or...
Forum: support.Hardware 23 June 2018, 20:07
Replies: 3
Views: 394
Posted By pandy71
You can't reprogram those chips - they are truly...

You can't reprogram those chips - they are truly MASK ROM - Commodore ordered them from few companies - at the beginning (Kick <2) it was Japan (mostly Hitachi), later (Kick >2?) it was Macronix...
Forum: Hardware mods 10 June 2018, 15:01
Replies: 34
Views: 2,409
Posted By pandy71
This seem to be proper answer - usually this is...

This seem to be proper answer - usually this is button to start and if it keep pressed longer then it perform COLD shutdown (independent from OS).

I agree that 500W is ridiculous and usually...
Forum: support.Hardware 15 May 2018, 23:23
Replies: 9
Views: 525
Posted By pandy71
Not sure but perhaps original PSU using voltage...

Not sure but perhaps original PSU using voltage doubler - this is quite common for US/EU PSU's - they have switch to use PSU in voltage doubler or normal mode - if this is similar for this PSU then...
Forum: support.Other 15 May 2018, 18:08
Replies: 1
Views: 609
Posted By pandy71
If this monitor support CGA then it should work...

If this monitor support CGA then it should work with Amiga - use VGA input as it is proper input for video signal generated by Amiga (analog video) MDA, CGA, EGA are digital signals and they will...
Forum: support.Hardware 14 May 2018, 20:05
Replies: 12
Views: 912
Posted By pandy71
I didn't mean to insult anyone especially...

I didn't mean to insult anyone especially E-Penguin, well yes, i've tried to be funny and a bit of ironic (being from almost 20 years electronics engineer i've had impression that have some basic...
Forum: support.Hardware 13 May 2018, 15:39
Replies: 12
Views: 912
Posted By pandy71
Thank you. So please tell me what makes coil...

Thank you.

So please tell me what makes coil to whine?
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