Looking for a couple beta testers for my new ZX81 interface

BeanBean Posts: 8,068
edited 2019-09-20 - 00:09:34 in Propeller 1
I know there are some ZX81 fans on this forum, so I thought I would ask here.
I have developed an interface for the ZX81 using the Propeller.
It gives the ZX81 the following features:

3 channel sound (tone/noise/pwm)

Wii Classic Controller interface

VGA - The video modes constrained by the Propeller RAM.
1) Low Resolution (128x120 pixels, every pixel can be any of 64 colors)
2) Medium Resolution (256x192 pixels, 4 colors, every 8x8 cell can be any four of the 64 colors)
3) High Resolution (512x192 pixels, 2 colors, every 16x8 cell can be any two of the 64 colors)

Everything is controlled by POKE and PEEK so it is usable from BASIC.

I am looking for one or two people to be beta testers. You need to be able to test the interface with BASIC and assembly. Of course you will need to have a ZX81 or TS1000 computer too.

If you are interested please reply here, or send me a private message. I will choose in the next week or two.

Thanks,
Bean
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Comments

  • Wow, that takes me back... I remember programming the ZX81 a very long time ago... Barely recall doing a bunch of PEEK and POKE on it...

    Couldn't you also emulate the ZX81 with the propeller?
    Prop Info and Apps: http://www.rayslogic.com/
  • I have both a ZX81 and TS1000. I would be happy to help beta test!

    Unfortunately, it's going to be a couple weeks or so before I can. We're moving into a new home next Friday (9/27). Then, I have to empty the contents of my storage buildings into the new house after that.

    My equipment is tucked away in those buildings (our house is almost empty).

    But when I get settled in, I'd be happy to help any way I can.

    Feel free to email me if you want.

    cbmeeks [at] gmail [dot] com

  • I don't have a ZX81 but I see you can still buy the kit for only $999!

    http://www.zebrasystems.com/nyc/index.php/timexsinclair/timex-sinclair
  • PublisonPublison Posts: 11,060
    edited 2019-09-20 - 20:36:47
    David Betz wrote: »
    I don't have a ZX81 but I see you can still buy the kit for only $999!

    http://www.zebrasystems.com/nyc/index.php/timexsinclair/timex-sinclair

    $999 !!!
    You can get used ZX81 on ebay for less than $100.

    https://www.ebay.com/sch/i.html?_from=R40&_nkw=ZX81&_sacat=0&LH_TitleDesc=0&rt=nc&LH_Complete=1
  • I have nearly 100 vintage computers in my collection. I deal with that kind of crap all the time. People thinking their Apple IIe or ZX Spectrum is a rare artifact worth thousands of dollars. Or, worse, they KNOW it's not worth very much but hope some naive collector will pay up.

    I don't remember what I paid for my ZX81 (it was nearly mint in original box, RAM expansion, manuals, etc.) but I know I didn't pay $50 for it shipped.
  • cbmeeks, Thanks. I was hoping you would reply.
    I'll contact you in a couple weeks to get the module to you.
    I should have all the firmware bugs worked out by then.
    What I really need is someone to help me test the module with assembly language so I can find the bottlenecks and fix them.
    Everything pretty much has been tested using BASIC and works.

    One thing I was surprised by is how fast the ZX81 is in fast mode. It it just as fast if not faster than a C64 or Apple II.
    I think some really good games can be made using this module.

    Thanks again and I'll be in touch.

    Bean
  • cbmeeks wrote: »
    I don't remember what I paid for my ZX81 (it was nearly mint in original box, RAM expansion, manuals, etc.) but I know I didn't pay $50 for it shipped.
    I think I paid $79 for my new ZX81 way back in the early 80's. I bought it directly from Sinclair via mail order from their US office (which I think was in Boston but I could be mistaken).

    I also have a TS2068 and a Sinclair QL. All of these are stored in a box in the bottom of a closet and I haven't even looked at them in years...

  • I think it was 1982 or 83 when I got my Timex Sinclair 1000 with it's "massive" 2K of RAM.
    Then I had to work to save up for the 16K ram pack and the printer. My family was quite poor, so $50 in 1983 was quite a bit of money for my parents.
    My best friend at the time got a CoCo for Christmas and we would go to each others houses to write programs. Sometime we would "sleep over" but, of course we didn't sleep, we would write code all night. We both "discovered" assembly language and kind of went our separate ways as he had a 6809 and it was quite different than my Z-80.

    Bean
  • Will your board work with the TS1000? There seem to be some of them for fairly reasonable prices. Will you be selling these?
  • zx81vgazx81vga Posts: 53
    edited 2019-09-21 - 14:25:16
    Hello @Bean

    I developed zx81vga for the Propeller.

    Your Project is very cool. :cool:

    I got my 1. ZX81 1983 with 1 KB RAM.
    Then upgrade to 16 KB !!! (Wobble).

    In my House live 2 ZX81 and 1 TS1000
    I'm very interested on your Project.

    I love Z80 Assembler, and i think there is much more to do... :lol:

    Feel Free to Send me a PM.

    Greetings from Nuremberg, Germany

    Werner


    PS.

    Whats about Load/Save?
    SD-Card or Tape? :confused:
  • David Betz wrote: »
    Will your board work with the TS1000? There seem to be some of them for fairly reasonable prices. Will you be selling these?

    Yes, they will work with the TS1000, that is what I use.

    I plan to sell them as a kit for $69.99 and $99.99 assembled. They are all thru-hole parts.

    If they are popular, I will redesign it to use SMD parts and sell them assembled only.

    Bean
  • Werner, Thanks. I was hoping you would reply.

    I will send you a private message to get your address.

    It will probably be a couple weeks until I have the firmware completed.

    It does not have any save/load or SD card. It is compatible with the ZXtend if you move the memory out of the 8K to 16K area. Using "CONFIG M=H".

    Bean
  • Bean wrote: »
    David Betz wrote: »
    Will your board work with the TS1000? There seem to be some of them for fairly reasonable prices. Will you be selling these?

    Yes, they will work with the TS1000, that is what I use.

    I plan to sell them as a kit for $69.99 and $99.99 assembled. They are all thru-hole parts.

    If they are popular, I will redesign it to use SMD parts and sell them assembled only.

    Bean
    Thanks! Maybe I'll look for a TS1000 once your kit becomes available. It looks cool.
  • @Bean, how does the interface handle the commands from the ZX80? Especially in regards to the VGA generation. Do you insert wait states or slow the computer? IIRC, the ZX81 runs around 3.5 MHz (slightly slower than NTSC). Do you devote more than one cog to intercept the signals from the computer?

    Thanks!
  • It should work on the ZX80, it is just memory mapped to the 8K to 16K region.
    It only uses 4 memory addresses, but partial decoding repeats these thru the whole 8K to 16K region.
    This works out because then you can use IY with a negative offset to poke it without using any registers.

    It uses one "command" address, two "parameter" addresses, and one "status" address.

    You can poke to each of these without waiting, but if you want to poke to the same address again, you must read the "status" address and look at bit 7 which is the "busy flag".

    The propeller can read all four addresses with one cog, but writing (Z80 READ) is more time constrained and I must have a cog for each address.

    I have a forum setup for the module at zxgame.forumotion.com all the files are there (no source code though).

    If you want I can send you one. If you are interested send me a PM with your address. I just ask that you actually use it and report any problems.

    Bean

    P.S. Oh wait, the VGA generation is NOT a duplicate of the normal ZX81 screen. It is a separate display. If that is what you were asking.
  • Bean
    I just saw this post and I know I'm late for the party but are you still looking for testers? I have a working TS1000 and experience with Z80 assembly.
  • Blitted2,
    Send me a PM with your address and I'll send you one.

    Bean
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