Search found 175 matches

by olofsen
Tue Jun 16, 2020 9:02 am
Forum: Software
Topic: ZigZags by Noice, colorized
Replies: 2
Views: 417

Re: ZigZags by Noice, colorized

It seems NXTLIN points to a line at 403C where there is a USR 16458 (8F 00 94 00 00). The ZigZags look very good with colours! :)
by olofsen
Fri Jun 12, 2020 7:45 pm
Forum: Development
Topic: ZX81 interrupts with z88dk, how to install an ISR ?
Replies: 19
Views: 1643

Re: ZX81 interrupts with z88dk, how to install an ISR ?

So the address may be located by disassembling the P file and looking for the end of the alternative DISPLAY-3: 4167 ed44 neg 4169 3c inc a 416a 08 ex af,af' 416b d3fe out (0feh),a 416d 2a8b41 ld hl,(418bh) 4170 23 inc hl 4171 228b41 ld (418bh),hl 4174 7c ld a,h 4175 b5 or l 4176 c27d41 jp nz,417dh ...
by olofsen
Thu Jun 11, 2020 6:49 pm
Forum: Development
Topic: ZX81 interrupts with z88dk, how to install an ISR ?
Replies: 19
Views: 1643

Re: ZX81 interrupts with z88dk, how to install an ISR ?

Just a note that the clock available here https://sinclairzxworld.com/viewtopic.php?p=17265#p17265 hooks up an ISR, but I don't remember all details... The address of a C function (although consisting of assembly code) is "poked" to the startup code of the ISR that z88dk installed, at 0x41b4.The sou...
by olofsen
Tue May 19, 2020 7:03 pm
Forum: Development
Topic: New ToddyForth with built-in editor & block storage (Was: TasWord as editor for ToddyForth)
Replies: 31
Views: 1278

Re: TasWord as editor for ToddyForth

Great article :) Trying it I got stuck before step 1 ;) of the workflow though, combining TasWord with your patches... Could you perhaps show how to use SIMDOS2 for this purpose?
by olofsen
Thu Jan 23, 2020 7:52 am
Forum: Emulators
Topic: Emulating musical tones using cassette out - help!
Replies: 7
Views: 2228

Re: Emulating musical tones using cassette out - help!

Indeed, the code is used only for the first value in the sound buffer after an IN or OUT. The "newpos" and "subpos" variables are calculated like an integer division and a remainder. So I guess the "subpos" variable smoothes things a bit by not taking the initial value itself, but taking into accoun...
by olofsen
Mon Jan 20, 2020 11:52 pm
Forum: Emulators
Topic: Emulating musical tones using cassette out - help!
Replies: 7
Views: 2228

Re: Emulating musical tones using cassette out - help!

Some quick thoughts: Indeed with IN the signal should go low, and with OUT high, which would suggest the sound_beeper argument in sz81 is reversed. And indeed INs (with an even port number) are prevented to cause VSYNCs when a program is running, which is with NMIs in SLOW mode. The IN/OUT works as ...
by olofsen
Fri Oct 04, 2019 11:10 pm
Forum: Development
Topic: ZXmore - infos & updates
Replies: 59
Views: 21380

Re: ZXmore - infos & updates

Tim, do you still have a jumper at J12 to set the i/o address to the one the ZXmaster is expecting?
by olofsen
Sat Sep 21, 2019 9:19 am
Forum: Software
Topic: Load files to any memory location without ZXpand
Replies: 3
Views: 3143

Re: Load files to any memory location without ZXpand

LET LIKES=LIKES+1 :)
by olofsen
Sun Sep 08, 2019 12:23 pm
Forum: Hardware
Topic: 32 kb ROM patch.
Replies: 9
Views: 1199

Re: 32 kb ROM patch.

Does setting RAMTOP to $0000 work as well on a real ZX81?
by olofsen
Thu Sep 05, 2019 8:44 pm
Forum: Emulators
Topic: sz81 emulator
Replies: 23
Views: 8997

Re: sz81 emulator

The 2.3.10 source and Windows binaries have been updated with a minor change for UDG. Without this change, the first "BBB" video worked, but hopefully now also the new example videos. A difference is that switching off WRX doesn't seem to be necessary. Hopefully the minor change does not give issues...