ZXblast - ZX81 memory extension plus USB

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PokeMon
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ZXblast - ZX81 memory extension plus USB

Post by PokeMon » Sat Mar 19, 2016 6:15 pm

Hi there,
some people already got some information about a new memory extension for the ZX81.
Here it is, called it ZXblast, that blows up the features of a ZX81 and let you have a blast with your old ZX81.

It may be used with the DIN 41617 connectors (64 pins a/c row like used in the german ZX team) or the standard expansion connector and has dimension of 100x80 mm or half size "europe board" (4.0 x 3.15 inches). In fact this is a cheap memory extension plus using USB flash memory/sticks for loading and saving data and offers SRAM and Flash ROM with either each 128k or 512kByte depending on what memory type is used. The business logic is inside a CPLD which allows to have several features like RAM banking, different ROM types and partly additional features the ZXmore offers (not all possible).

The USB ports may be used mainly for flash memory sticks but also additional hardware like joysticks or similar. I think there will be a cheaper starter version for people only need memory extension and loading/saving files and maybe bigger memory and more features for the power users with a bigger CPLD. This should be available around april or latest may this year. So just an announcement when you need a mass storage device with memory extension. Not 100% sure about pricing but the basic version should be in the range of about 25 GBP as self construction kit or 30 GBP ready to use (plug and play).
ZXblast4.png
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sirmorris
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Re: ZXblast - ZX81 memory extension plus USB

Post by sirmorris » Sat Mar 19, 2016 6:26 pm

Looking good, Karl! If you need a beta tester... ;)
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

Prime
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Re: ZXblast - ZX81 memory extension plus USB

Post by Prime » Sun Mar 20, 2016 2:39 am

Indeed looking good.

Out of interest what are you using to talk to the USB, I guess you have something on the bottom of the board?

Cheers,

Phill.

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mrtinb
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Re: ZXblast - ZX81 memory extension plus USB

Post by mrtinb » Sun Mar 20, 2016 8:15 am

Can you make a short comparison between ZXblast and ZXpand?
Last edited by mrtinb on Mon Mar 21, 2016 5:17 am, edited 1 time in total.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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PokeMon
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Re: ZXblast - ZX81 memory extension plus USB

Post by PokeMon » Sun Mar 20, 2016 12:03 pm

The USB controller is on the bottom side of the board and already soldered, it's the FTDI VNC2 chip used on the ZXmore - this way I can use quite much code of ZXmore and shorten development time (software). I can not exactly compare it with the ZXpand because I do not know ZXpand very well and I do not know very well where the limits of ZXblast are exactly. :mrgreen:

I am quite sure it will offer up to 56k RAM, load and save via USB and use of other ROMs than ZX81 (maybe up to 10 to choose from and easily to program when copied on a USB stick). There are some more options like banking RAM which mechanism is not yet defined. I think the main difference is to use USB flash media instead of SD cards and does allow other USB hardware as well as connecting a joystick, other keyboard depending on controller software/memory. I have to check out a few things but SD card is limited to storage only.

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1024MAK
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Re: ZXblast - ZX81 memory extension plus USB

Post by 1024MAK » Sun Mar 20, 2016 12:12 pm

Some info on the ZXpand here (scroll down a bit) and here.

Mark

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PokeMon
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Re: ZXblast - ZX81 memory extension plus USB

Post by PokeMon » Sun Mar 20, 2016 12:24 pm

Okay - there is no AY support while the ZXpand also needs an additional AY module. So for sound you have to use an additional regular external AY module.

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PokeMon
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Re: ZXblast - ZX81 memory extension plus USB

Post by PokeMon » Mon May 02, 2016 6:02 pm

Some news about ZXblast - the boards are here and in the meanwhile I made a short test with programming it as plain 16k RAM extension and works as expected. So the CPLD programming has to be developed further for the other features and some software extracted from ZXmore to control the USB chip and some testing. Hopefully it will be available for sale in about 2 weeks now. Not too much work for it now necessary. Will have time for it next week.

Here are some pics:
IMG_9071k.JPG
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IMG_9070k.JPG
IMG_9070k.JPG (81.39 KiB) Viewed 1688 times

And this is the completed board:
IMG_9072k.JPG
IMG_9072k.JPG (94.53 KiB) Viewed 1688 times

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PokeMon
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Re: ZXblast - ZX81 memory extension plus USB

Post by PokeMon » Mon May 02, 2016 6:06 pm

This is the backside.
Unfortunately, there is a small bug with 3 wires, crossing a pad.
Modified something and forgot to run design rule check again. :?

Here it is fixed with some bigger copper wires in orange colour, the final solution uses thinner copper wires in blue color which are not that prominent. The wires are soldered already when shipping the plain board and of course for completed memory packs.
IMG_9073k.JPG
IMG_9073k.JPG (90.94 KiB) Viewed 1689 times
IMG_9083k.jpg
IMG_9083k.jpg (157.36 KiB) Viewed 1689 times

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Re: ZXblast - ZX81 memory extension plus USB

Post by RWAP » Mon May 02, 2016 6:47 pm

This is great news :D

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