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Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-28, 11:35

Just lowered the CMOS clock speed to 32kHz, by: 1) Halving the 128kHz clock speed by removing the useless second Square Wave output which isn't used. 2) Halving the then-64kHz clock speed by doubling the rate of the half clock(decreasing all taps by 1, which can be done because taps 1&2 aren't used( …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-28, 10:37

It seems it's correct: 8kHz is the maximum speed: The lower four bits (0-3) of status register A select a divider for the 32,768 Hz frequency. The resulting frequency is used for the periodic interrupt (IRQ 8). The system initializes these bits to 0110 binary (or 6 decimal). This selects a 1,024 Hz …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-28, 03:49

Looking at the docs again. The RTC ticks at one tap higher than the square wave, so minimum of value(decimal) 3=>tap 3=8kHz interrupts. Edit: BUT, all rates are decreased by one. Thus rate 3(8kHz)=>tap 2. Tap 2 is shifted left one to obtain tap3 for the non-square wave variant thus every 8 ticks. …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-28, 02:10

I've added the code for my timing of the RTC above in my previous post. Edit: Wait a sec..... Is this call: RTC_Handler(lastsecond); //Handle anything that the RTC has to handle! not in the wrong position? It's handler is supposed to be called at 64kHz, like the time update directly above it, but …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-28, 01:48

Just tried the setup with the new (almost 100%) cycle-accurate system. It still fails with a "0152 error -system board"? I know that it's supposed to be a 32kHz crystal, but the multiplier is used for clocking correctly: Main clock handler at 131072Hz: OPTINLINE void RTC_Handler(byte lastsecond) // …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-27, 22:13

I guess to make it pass the CMOS test on that diagnostics floppy, I'll have to add an alternate timing mode to the RTC. So that instead of running in realtime(Windows clock), it'll run based on the last CMOS clock time(last saved CMOS status loaded in the CMOS during emulator start) combined with …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-27, 19:43

Just managed to update the Visual Studio projects for my two projects using the common emulator framework to call the batch file, thus automatically updating the version info when compiling for Windows in all cases. The same is applied(but through the Android Studio itself, using special gradle …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-27, 18:56

Took me a whole day to get automatic versioning fully working in a cross-compiler way. Now a single configuration file is used(which combines with other files to create the entire .res file from the .rc file for Windows). There's now two files containing settings: gitversion.h, which contains the …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-27, 04:09

You do know that the one on minuszerodegrees is probably corrupted in some way? It had more than 512 bytes left at the end(usually floppy disks are using 512-byte sectors). UniPCemu checks if the size is readable when mounting and rejects that disk image, because it cannot reliably read those …

Re: UniPCemu IBM AT emulation FDC/DMA issues?

Posted on 2018-01-27, 02:39

That AT diagnostics/setup disk on minuszerodegrees can't be used(on UniPCemu), so I did a bit of searching and found it by Googling it using the search terms "ibm pc diagnostics at 2.07" winworld . That disk image is the correct 360K disk image(7-zip reports leftover data on the one from …

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