Sinclair ZX80 / ZX81 / Z88 Forums

Of course that's also an option, but how did you guys solve the problem of flashing something that occupies the entire ram? :) I would say: it's a design fault to use a flash memory, which could only be erased/programmed in blocks bigger than the ram is ;) Kai uses in his ZX2000 a 512kB (that is bi...

I started a redesign with EPROM on board but it's turning into an address-bus nightmare :evil: ? You don't need to fetch the address lines of the ROM to use an external EPROM for rom patches: use the normal address lines at the edge connector and enable the external EPROM only during /RD cycles (no...

'll need to control /M1, /IORQ, /MREQ, /RD and /WR ... I suppose when the Z80 tristates these will float. Yes, you have to drive ALL Z80 outputs, which are not fixed to a specific level using pullup- or pulldown resitors (e. g. also /HALT and /RFSH). DMA state is the only legal mode, where you coul...

and some of us also C and BRAINF**CK

Siggi

The pure Z80 inside the ZX81 or Spectrum is not able to drive such a long cable. This would require line drivers and a well-terminated bus to avoid signal distortions. I made something similar to drive a very long cable to an external keyboard (for buffering of the Z80 address lines, used for keyboa...

All we need is for someone to selll a a blank cartridge which uses flash memory, and use a program on the PC side to flash the cart contents via the joystick port. It's 100% possible and it's now being done by Spectrum users!" According to the thread http://www.sinclairzxworld.com/viewtopic.php?t=1...

Perhaps you could describe your hardware a little bit more (which lines are driven by your hardware during DMA)?

Wilf's DMA solution seemed to work:

http://www.user.dccnet.com/wrigter/index_files/HS4.htm

HTH Siggi

Hi Charlie, the German ZX-Team uses a 64 pin VG connector to avoid any wobble. It has some pins free for additional signal (like video). If you would use the same connector, we could easily share the new and existing expansion cards. See Kai's pages for details: http://www.fischerkai.de/zxteam/zx96_...

Hello friends, I am sure the answer to be somewhere, but let ask it again : I have a program I call from the BASIC with the usual RAND USR XXXX But in the program I will use all the REG and the Stack. If you run the program in SLOW mode, NEVER touch the IX, IY and AF' registers, because they are us...

Meanwhile I think, that BRAINFUCK is an easier programming language: http://www.youtube.com/watch?v=OnQobTyqEd0 And Matthias wrote a brainfuck interpreter for the ZX81: http://www.swatosch.de/zx81/brainfuck.p For details: see http://forum.tlienhard.com/phpBB3/viewtopic.php?f=2&t=275&start=0 :mrgreen...