Search found 62 matches

by Tony Brewer
24 Nov 2018 19:42
Forum: SOFTWARE
Topic: New tape cleaner tool
Replies: 36
Views: 2232

Re: New tape cleaner tool

What would be read? In normal operation an interrupt is triggered on an edge (can't remember which on). Would not the bit read just reflect if an edge has been detected or not? As an aside, one of these days, when the emulators are up to it, I would love to write a tape loader with music and loadin...
by Tony Brewer
19 Nov 2018 22:27
Forum: SOFTWARE
Topic: New tape cleaner tool
Replies: 36
Views: 2232

Re: New tape cleaner tool

Does the CTC set a register that can be polled? Yes, here is an extract from the Zilog Z80 Family User Manual: The Down-Counter The down-counter is an 8-bit register that is used in both COUNTER and TIMER modes. This register is loaded by the Time Constant register both initially, and when it count...
by Tony Brewer
19 Nov 2018 15:47
Forum: GENERAL DISCUSSIONS
Topic: Problems with Ads on Memorum?
Replies: 13
Views: 1111

Re: Problems with Ads on Memorum?

The offending lines in the forum code are: <!-- Begin BidVertiser code --> <SCRIPT data-cfasync="false" SRC="//bdv.bidvertiser.com/BidVertiser.dbm?pid=824774&bid=1967045" TYPE="text/javascript"></SCRIPT> <!-- End BidVertiser code --> The imported javascript could be changed at any time, and do diff...
by Tony Brewer
19 Nov 2018 01:10
Forum: SOFTWARE
Topic: New tape cleaner tool
Replies: 36
Views: 2232

Re: New tape cleaner tool

muldjord wrote:
19 Nov 2018 00:45
I guess you could poll it continually. The speed of the cpu should be sufficient to just continually read and somehow compare the output. It would be inefficient I believe, but should work.
What is "it"? There is no cassette input that can be polled directly.
by Tony Brewer
18 Nov 2018 22:23
Forum: SOFTWARE
Topic: New tape cleaner tool
Replies: 36
Views: 2232

Re: New tape cleaner tool

A tape-related conundrum for you: The MTX is interesting because the cassette input is via the CTC, which can be configured with this code: LD C,0BH ;CTC channel 3 port LD B,0C5H ;Enable interrupt, counter mode, trigger on C/T3 falling edge LD A,1 ;Time constant = 1 OUT (C),B OUT (C),A Could there b...
by Tony Brewer
27 Oct 2018 14:41
Forum: SOFTWARE
Topic: Thoughts on Einstien "Stolen" Software?
Replies: 5
Views: 574

Re: Thoughts on Einstien "Stolen" Software?

Mark, it was taken aback but once I realised there was a solution it didn't take very long. All done the same day, I think.

Instead of one of C/T0, C/T1 or C/T2 tied to /VDPINT they are all connected to 2 MHz - a strange design decision.
by Tony Brewer
19 Oct 2018 16:17
Forum: SOFTWARE
Topic: Thoughts on Einstien "Stolen" Software?
Replies: 5
Views: 574

Re: Thoughts on Einstien "Stolen" Software?

The Einstein VDP /INT is not connected to Z80 /INT or /NMI or anything else. I couldn't believe it when I found out and therefore converting the Speculator was not as simple as it should have been. Luckily CTC channels 2 and 3 can be cascaded (ZC2 tied to C/T3) and I programmed channel 2 in timer mo...
by Tony Brewer
19 Oct 2018 15:10
Forum: HARDWARE
Topic: NTSC/PAL VDP setup?
Replies: 10
Views: 798

Re: NTSC/PAL VDP setup?

The VDP datasheet says: Note: Enabling bit 7 (actually bit 0/LSB) in the TMS9928A/9929A causes A-Y and B-Y to go to the sync level only when all planes in front of the pixel under question are transparent. I have no idea what they mean by this. A-Y is an error and should be R-Y . More from the data...
by Tony Brewer
03 Oct 2018 15:37
Forum: SOFTWARE
Topic: Thoughts on Einstien "Stolen" Software?
Replies: 5
Views: 574

Re: Thoughts on Einstien "Stolen" Software?

A diskette was sold that allowed some extra Spectrum games to run on the Einstein Speculator which I knew nothing about at the time, despite it being my device. The Einstein had an interesting hardware "feature" - the VDP /INT pin was not connected to anything! I met the chief designer during a visi...
by Tony Brewer
06 May 2018 22:04
Forum: NEW HARDWARE
Topic: Rodents anyone ?
Replies: 17
Views: 1600

Re: Rodents anyone ?

What if the CP/M BIOS set up a frequent interrupt to read the mouse keys?