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#1

2.15.0.0
Hello Rob.
Thanks for your warm welcome.

I mostly split time for retrocomputing between Amstrad CPC and MSX2 computers. There's a lot of new games and demos on these two.
I also enjoy DOS gaming on real machine with my HP Vectra 500 Pentium 166Mhz from 1995. I upgraded it a little with 112Mb RAM, 32Gbx2+64Gb CF Card on IDE and SoundBlaster AWE64 connected to Roland MT-32, SC-88 and JV-1010 MIDI expander for the best sound experience.
#2
I didn't swap it. It's actually flat and fine. Just a play of the light.
#3

Quote from: zhulien on Today at 11:23what exactly are the parts of the real CPC that the timings have issues with and which can be overcome on real hardware somehow - i.e. raster RAM chips? faster ROM chip? (I'm guessing)
1us Divided into z80 1/4 time GA 3/4 time to read 2 bytes. A simple speed 2x increase results in too much data to display. Either 100Hz frame and 600Hz interrupt, or change GA to only download 1byte for 1 nop. ROM you can replace FRAM. 
#4
Hi,
I managed to short out my PCW analogue board (Deeply annoyed with myself!)

I think I blew the STK7308. I'm using a pcw 9256. The data sheets are really unhelpful and I was trying to work out the voltages you'd expect on the stk's pins

With the STK in circuit, the board blows the overprotection diodesd d505 d511 and d512.
R501 gets very hot then burns out.

Removing the STK means none of this happens.

The transformer windings dont seem to be shorted (there is 'OL' reading if compare primary to secondary pins).

I just wanted to check before I solder in a new STK7308 to minimise the risk of killing it if Ive missed something!

Thanks
#5
Quote from: GUNHED on Today at 00:03EDIT: Seems to be very compatible (?), now... seriously... Amstrad should have use it!
Interestingly nobody ever offered it as upgrade or so. 
Indeed, that would have been nice, if they would have included it from the beginning. Probably it was
  • too expensive
  • or too risky (as no other provider than Hitachi)
  • or not available in the right quantities

Maybe even all of it...


Regarding the upgrade: were there any (successful) upgrades that required desoldering a big IC in the CPC? that's usually quite a risky procedure that not many will do.


Btw: I could not find any reference where that IC was actually used. I see it's included in the MAME sources so probably in some arcade machines. But other than that, it's hard to find any information.
#6
The raster is preserved there. This will be the most expensive part of the (non)CPC fun.
#7
Just curious, the Terasic T-Rex can run the CPC at 24Mhz and it seems pretty reliable - I know it's an FPGA core, but from a timing point of view in relation to a real CPC, timing seems to always come up as an issue - what exactly are the parts of the real CPC that the timings have issues with and which can be overcome on real hardware somehow - i.e. raster RAM chips? faster ROM chip? (I'm guessing)... and why don't such FPGA cores have timing issues even if internally?
#8
Building an Amstrad with an eZ80 would be fun. A couple of challenges with it though:

* The on device hardware uses I/O addresses starting at $80 (the high byte is ignored). You might have to patch software to avoid those addresses. Most software probably loads those bits high, which would be safe, but writes to the gate array have the register data on those bits. Register 2 could be problematic here. Although I think just setting bit 5 high should solve any issues.

* The eZ80 has no memory manager on board. That means you'll need to use external RAM and ROM. At 50MHz the clock cycle time is 20ns[0]. The fastest parallel RAM chips available appear to be about 10ns. The fastest ROMs about 55ns. Once you add in gate delays for whatever you're using for the memory manager (CPLD, FPGA) you're unlikely to be able to run at full 50MHz clock speed even reading from RAM.

But those issues aside, it's certainly do-able and, as I said, would be fun <g>.

A 20MHz Z80 on the other hand would be far easier. You'll need to replace the DRAM with faster modern SRAM and rejig the gate array timings. But neither of those overly complicated.

  • I'm assuming here that the read cycle is a single clock cycle. It certainly is for internal memory. Either way you'll need that single cycle read for the best performance.
#9
Quote from: McArti0 on Today at 09:18
Quote from: andycadley on Today at 07:41That probably won't...
That's why I joined the queue for 6128 PCB replica. I don't want to solder on my antique. What I have in mind is a printed model for assembly, the CPC6128 case. ;D
I don't mean physically won't work, I mean the actual functionality won't work with the way the Amstrad hardware has to decode addresses. It doesn't really use the CRTC MA and RA signals the way they're intended and the way it does use them won't work with the way the "wider window" approach works.
#10
avatar_pmeier
Other retro / C64 emulator with debugger?
Last post by pmeier - Today at 10:49
Hi,

I'm looking for a C64 emulator with a debugger that is comparable with the WinAPE debugging features.

I have tried no$c64 and RetroDebugger.

I'm a little bit disappointed. Are there any better ones?

My review results (IMHO):
RetroDebugger: Very old fashioned multi window interface. Disassembler font too small.
no$c64: No sound (ok for me), had to modify the game I wanted to analyze, but probably my choice for now.
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