Search found 52 matches

by Mike
Thu Jul 17, 2008 2:09 pm
Forum: Hardware
Topic: ZX81 Motherboard
Replies: 35
Views: 21206

Re: ZX81 Motherboard

My guess is they are using the logic to detect a certain address in the ROM, and changing a few bits on the data bus to write a new opcode out on the bus, thus changing one single instruction. Very clever fix. I guess since the ROMS are special custom chips, not just EEPROMS, it was too expensive t...
by Mike
Mon Jul 14, 2008 7:25 pm
Forum: Hardware
Topic: ZX81 Motherboard
Replies: 35
Views: 21206

Re: ZX81 Motherboard

That page doesn't quite add up to me... The description describes extra ROM piggybacked on top of the original ROM. However, the picture shows a couple of 74LS logic chips (A triple 3 input NOR and a triple 3 input NAND) on top of the Z80 with no extra ROM in sight. Looks more like someone screwed u...
by Mike
Sat Jul 12, 2008 6:38 pm
Forum: Development
Topic: 8K Adventure ported to the ZX-81?
Replies: 114
Views: 81079

Re: 8K Adventure ported to the ZX-81?

yerzmyey wrote:I wonder why the file http://www.user.dccnet.com/wrigter/inde ... es/BMP2P.P You pointed doesn't work with EughtyOne emularor...
Because you haven't enabled WRX graphics in the Hardware dialog box...

Mike
by Mike
Sat Jun 28, 2008 10:04 am
Forum: Emulators
Topic: EIGHTYONE PROBLEM
Replies: 14
Views: 35773

Re: EIGHTYONE PROBLEM

I'm having a problem with loading .p or .o files. Once I select them, it should automatically LOAD "", but it doesn't. In previous uses of Eighty-One, I never had a problem with it. Now I do. Is this an error? You can turn on/off auto loading of files by opening the Tape Manager (Options->Tape Mana...
by Mike
Fri Jun 20, 2008 9:39 am
Forum: Development
Topic: DEMOS FOR ZX81/TS1000/TS1500??????
Replies: 3
Views: 5224

Re: DEMOS FOR ZX81/TS1000/TS1500??????

Ah, SP81.

That's stored on a hard drive from a PC that's long died. I'll dig it out sometime and put it on the web for you.

Mike
by Mike
Sun Jun 15, 2008 10:02 pm
Forum: Emulators
Topic: Firm Zeddie
Replies: 10
Views: 13741

Re: Firm Zeddie

If you're looking for a clock accurate emulation of the Z80 in software, maybe the best place to start would be something like the VHDL source for T80?

http://www.opencores.org/projects.cgi/web/t80/overview

Mike
by Mike
Sat Jun 14, 2008 8:02 pm
Forum: Emulators
Topic: EIGHTYONE PROBLEM
Replies: 14
Views: 35773

Re: EIGHTYONE PROBLEM

Speed and sound emulation are linked. I think the speed issue is due to the inaccurate timer I'm using - once I've rewritten the sound code, the timing will then depend on the accuracy of how fast DirectSound empties it's buffer (Hopefully, 44.1khz is really 44.1khz etc) and the speed will be more a...
by Mike
Sat Jun 14, 2008 3:36 pm
Forum: Emulators
Topic: EIGHTYONE PROBLEM
Replies: 14
Views: 35773

Re: EIGHTYONE PROBLEM

eighty-one: ql emulation never starts, load from audio source doesn't work yet, support of .p and .o files?, speed? everything is too slow, even loading from a wav file takes longer than what it would take on a real ts2068. support of TS2068 joystick is really needed for some joystick-only programs...
by Mike
Fri Jun 13, 2008 6:43 pm
Forum: Sinclair Misc
Topic: THE ZX81 POCKET BOOK
Replies: 6
Views: 7582

Re: THE ZX81 POCKET BOOK

I haven't got a copy, but around 15 years ago I borrowed it from my local library and kept it for 6 months... The Adventure system in the book does work. There are a number of adventures written with it - the only name I can think of atm is "greedy gulch". Oh, hang on a min... all the adventures on ...
by Mike
Fri Jun 13, 2008 6:36 pm
Forum: Development
Topic: Text Adventures on the ZX-81?
Replies: 7
Views: 10226

Re: Text Adventures on the ZX-81?

The interesting thing about the ARTIC adventures, is if you look at them in a hex editor all the text is in ASCII not ZX81 character set. They must have been ported from another system...

Mike