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Memory Contention: A Hypothetical Fix?I have just had this crazy thought: If one were to wire an additional memory chip, say a 6264 8Kx8 SRAM, in parallel with the main memory so that it …
... reduce the effect of memory contention considerably. Possibly with the addition ... ULA is reading from, would halt the Z80 only if the ... -
Memory Map/ContentionHi I'm new to speccy coding (well I did some z80 coding a few years back - like 20yrs ago :) ), and I'd like to get back into writing some scrolling…
... a correct map for memory contention?
Address Size Area ... -
I/O contention model questionHi everyone, Sorry for my poor english. Together with a friend we are working on ZX Spectrum 48k implemented in FPGA. We have found bug in the Spect…
... .s faq describing I/O contention.
The 48k ... to lead to the following contention patterns:
High ... /> in 40 - 7F? | Low bit | Contention pattern
------------+---------+-------------------
No | Reset ... -
Contention and floating bus timingHello, I was recently playing a bit with memory contention and floating bus stuff in ZXDS and there is one thing which puzzles me a bit. It is the d…
... playing a bit with memory contention and floating bus stuff in ... sense it starts applying the contention a few cycles earlier, namely ... -
Some ever noticed that +2A/+3 halts Z80 using WAIT?I mean: Anyone ever noticed that the +2A/+3 halts the Z80 using WAIT? All documentation I've read about contention state that the ULA halts the Z80 …
... documentation I've read about contention state that the ULA halts ... mount ULA) uses WAIT to halt the CPU. I haven't ... at the screen RAM, so contention should be strong here.
BEEPER music compo 10-11 July on Di:Halt partyoh yeah! public pressure organizers [B]Di:Halt [/B]which will take place [B]July 10-11[/B], agreed to hold the [B]beeper music compo[/B]. The rules…
... ! public pressure organizers [B]Di:Halt [/B]which will take place ...128K Contention - How to get it right?With my recent hardware hackery, I've built a 128K (toastrack) clone. I can't quite get the contention right though. What I'm lack is a clear descri…
... 0x7ffd, 0xbffd and 0x3ffd port contention behaviour.
... However, I find that contention is applied too often ... /> To correct the excessive contention, I replicated ULA14 and ULA15 ... someone describe accurately the contention behaviour for the 128K ...28-character wide multicolour(ish) on 48k SpectrumLong-time lurker here... I've always been interested in rainbow effects on the 48k Spectrum, mainly from a perspective of "Just what [I]would [/I]ha…
... like crazy the moment the contention-free period starts. We get ... to mess around with the contention, so maybe you could get ... /> LD B,L
TSLP3 HALT ; Hang around, modifying the instructions ... at the start of the contention-free period
PUSH BC ...BIT b,(ii+n) contentionThe documentation says that BIT b,(ii+n) has this contention pattern: pc+1:4,pc+2:3,pc+3:3,pc+3:1 x 2,ii+n:3,ii+n:1 See [url]http://scratchpad.wiki…
... b,(ii+n) has this contention pattern:
pc+1 ... Tstate.
So the contention pattern should be:
Is there an SNA halt bug?Hello all, I noticed that some SNAs don't work on my emulator but they do work in almost everyone else's, SPUD fails with them too which is a tad sp…
... to get stuck on the halt instruction. I can't find ... with regard to SNA and halt, does anyone have the details ...Address bus contents (i.e. PC) during execution of HALTI'm wondering if anyone can tell me what's placed on the address bus during execution of HALT, beyond the initial M1 cycle. The Z80 user manual state…
... address bus during execution of HALT, beyond the initial M1 ... contains the following code for HALT:
[CODE] case ... the opcode fetch after a HALT could actually trigger paging ... of addresses well before the HALT operation finishes. While I ...Top Telly Tip... Halt and Catch FireThe series is set in the early 1980s and depicts a fictionalized insider's view of the personal computer revolution. The show's title refers to the f…
... the fictitious machine code instruction Halt and Catch Fire, which would ...HALT: Why always 4ts?Instruction breakdown of halt is like that: PC 4ts. That means it fetches instruction byte from ram which tooks 4 ts and then does nothing and read…
Instruction breakdown of halt is like that:
... or interrupt.
if halt is already read by cpu ... and again to execute the HALT, why it still takes 4 ... /> I mean if cpu executed HALT at cycle 5, and if ...Understanding contentionI'm trying to understand contention and its implications when some "weird" bus cycles (such as I/O cycles with I/O addresses in the contended memory …
I'm trying to understand contention and its implications when some ... both memory and I/O contention. Memory contention causes T1 to be ... ?
Also: memory contention makes T1 to be enlarged ... for instance, to avoid memory contention) that begins at the ...Question of contentionI'm not desperate to go digging through technical descriptions in depth, but one thing bugs me about the Speccy's video contention model - and that's…
... about the Speccy's video contention model - and that's the ... /> And then there's the contention pattern where the memory is ... 16, so that means the contention pattern covers a run of ..."Decoding z80 Opcodes" (http://www.z80.info/decoding.htm#intro) - Incorrect HALT Opcode?Apologies if this is a dupe but I searched within the forums and couldn't find anything. I've been working on a z80 emulator (for academic and rec…
... seems to incorrectly specify a HALT opcode as 0x7[i]7 ...ZXDS 1.3.4Hello, to celebrate the 35th Spectrum (and 10th ZXDS) anniversary, I have prepared [url="http://zxds.raxoft.cz/"]new ZXDS release[/url]. It fixes …
... just one very subtle contention bug in HALT emulation, which no one ...128K memory bank selection to avoid contention issuesI'm currently developing a game and I'm trying to get my head around the memory contention issues of the various 128K/+2/+2A/+3 spectrum models in or…
... my head around the memory contention issues of the various 128K ... what is the cause of contention for banks 1,3,4 ... downs due to this apparent contention issue.Writing own emulator: Contention questionsHi! (I don't know if this message should be here or in Hardware) I'm trying to write my own emulator just for the sake of it, and I'm having pr…
... having problems understanding the memory contention in 48k, in instructions like ... is being used there for contention.
Thanks ...Which Emulator has a menu option to enable Interrupts (EI) if emulated Speccy hangs after DI / HALT?Which Emulator has a menu option / debugger option to enable Interrupts (EI) if emulated Speccy hangs after DI / HALT? I tried SpecEmu and Fuse, b…
Which Emulator has a menu option / debugger option to enable Interrupts (EI) if emulated Speccy hangs after DI / HALT?
I tried SpecEmu and Fuse, but I can not find a option for doing this in their debugger.Zero v0.8Pigs can apparently fly because it's the v0.8 update of Zero that no one asked for but is out for public consumption anyway. Grab it [url="https:/…
... behaviour (ZJoyKiller).
- Fixed +3 contention bug (woody)
- Fixed mic ... snapshot (woody).
- Fixed incorrect HALT implementation (ZjoyKiler).
- Fixed incorrect ... (Hexaae).
- Fixed +3 contention bug (woody)
- Fixed issue ...The new GP2Xpectrum releases threadYeah, I know the thread title isn't exactly too original, but I've decided that just one post to hold all updates makes more sense than a lot of smal…
... - I was still applying contention emulation in a place where ... shouldn't when "no contention" was selected. Now the ... no contention mode will be less ... bug that made port contention not to be applied ... - Fixed a bug in HALT timing, it was taking 8 ...Has any programmers recently pushed the spectrum to the limits?Hi there. Ive just discovered this great forum and I was brought up with the speccy 16,48 and then 128k. Im just wanting to know if there are any re…
... /> LD B,L
TSLP3 HALT ; Hang around, modifying the instructions ... ; Hit here just as the contention-free period starts - start pushing ..."Programming the Spectrum in Assembly" series in Micro MartI see that Shaun Bebbington is starting a series of articles in Micro Mart magazine on how to program in assembly for those who might know a little b…
... -world algorithm which experiences more contention on a +2A/+3 than ... timings:
[code]
halt
xor a
ld ...LDIR timings in contended RAM?The 48K Spectrum technical reference page ([URL="http://www.worldofspectrum.org/faq/reference/48kreference.htm"]here[/URL]) describes the detailed ti…
... screen rendering immediately after a HALT you can reduce the contention.
