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zx81 ULA modules.

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  zx81 ULA modules. andy rea <ask_me@ask.me> - 2011-12-10 20:52 +0000
    Re: zx81 ULA modules. andy rea <ask_me@ask.me> - 2011-12-14 22:02 +0000
    Re: zx81 ULA modules. david <david.t.bastard@gmail.com> - 2011-12-17 04:15 -0800
      Re: zx81 ULA modules. andy rea <ask_me@ask.me> - 2011-12-17 15:37 +0000
      Re: zx81 ULA modules. Peter Liebert-Adelt <peter@zschopower.de> - 2011-12-17 22:52 +0100

#541 — zx81 ULA modules.

comming soon... ZX81 ULA module.

Plugs into original ula socket, provides composite video output 
(requires vwry small mod to bypass UHF Modulator, but still uses 
modulator output socket)..

But wait there's more, if your competent with a soldering iron the 
addition of 6 more wires you can enable enhanced operation :-

All software controlled by a simple POKE

1. inverted video
2. inverted border
3. switch between 60Hz and 50Hz
4. switchable M!not mod
5. turbo mode ***

*** turbo mode has some restrictions.

1. you must upgrade CPU to at least a Z80B (rated at 6Mhz but all i have 
seen will run at 6.5Mhz) or greater of course (i use 8Mhz)
2. Some ROMs in the ZX81's are too slow :-( i have found the motorola 
type to be useable.
3. if you have a soundcard you need to route the constant 3.25Mhz from 
the cpu to your sound card (or cut a track on the mainboard)

a quick PDF i knocked up here

http://www.debraclayton.webspace.virginmedia.com/zxulamk2.pdf

regards Andy

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#553

On 10/12/2011 20:52, andy rea wrote:
> comming soon... ZX81 ULA module.
>
> Plugs into original ula socket, provides composite video output
> (requires vwry small mod to bypass UHF Modulator, but still uses
> modulator output socket)..
>
> But wait there's more, if your competent with a soldering iron the
> addition of 6 more wires you can enable enhanced operation :-
>
> All software controlled by a simple POKE
>
> 1. inverted video
> 2. inverted border
> 3. switch between 60Hz and 50Hz
> 4. switchable M!not mod
> 5. turbo mode ***
>
> *** turbo mode has some restrictions.
>
> 1. you must upgrade CPU to at least a Z80B (rated at 6Mhz but all i have
> seen will run at 6.5Mhz) or greater of course (i use 8Mhz)
> 2. Some ROMs in the ZX81's are too slow :-( i have found the motorola
> type to be useable.
> 3. if you have a soundcard you need to route the constant 3.25Mhz from
> the cpu to your sound card (or cut a track on the mainboard)
>
> a quick PDF i knocked up here
>
> http://www.debraclayton.webspace.virginmedia.com/zxulamk2.pdf
>
> regards Andy

Now Availbale :-)

http://www.sellmyretro.com/offer/details/Brand_New_ZX-ULA2_for_the_Sinclair_ZX81_Home_Computer_%28FITTED%29-1984

Regards Andy

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#555

On Dec 10, 8:52 pm, andy rea <ask...@ask.me> wrote:
> comming soon... ZX81 ULA module.
>
> Plugs into original ula socket, provides composite video output
> (requires vwry small mod to bypass UHF Modulator, but still uses
> modulator output socket)..
>
> But wait there's more, if your competent with a soldering iron the
> addition of 6 more wires you can enable enhanced operation :-
>
> All software controlled by a simple POKE
>
> 1. inverted video
> 2. inverted border
> 3. switch between 60Hz and 50Hz
> 4. switchable M!not mod
> 5. turbo mode ***
>
> *** turbo mode has some restrictions.
>
> 1. you must upgrade CPU to at least a Z80B (rated at 6Mhz but all i have
> seen will run at 6.5Mhz) or greater of course (i use 8Mhz)
> 2. Some ROMs in the ZX81's are too slow :-( i have found the motorola
> type to be useable.
> 3. if you have a soundcard you need to route the constant 3.25Mhz from
> the cpu to your sound card (or cut a track on the mainboard)
>
> a quick PDF i knocked up here
>
> http://www.debraclayton.webspace.virginmedia.com/zxulamk2.pdf
>
> regards Andy

Very impressive - its a shame it's not possible to make a ZX81 clone-
kit using it (ZX11 anyone?!)

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#559

On 17/12/2011 12:15, david wrote:
> On Dec 10, 8:52 pm, andy rea<ask...@ask.me>  wrote:
>> comming soon... ZX81 ULA module.
>>
>> Plugs into original ula socket, provides composite video output
>> (requires vwry small mod to bypass UHF Modulator, but still uses
>> modulator output socket)..
>>
>> But wait there's more, if your competent with a soldering iron the
>> addition of 6 more wires you can enable enhanced operation :-
>>
>> All software controlled by a simple POKE
>>
>> 1. inverted video
>> 2. inverted border
>> 3. switch between 60Hz and 50Hz
>> 4. switchable M!not mod
>> 5. turbo mode ***
>>
>> *** turbo mode has some restrictions.
>>
>> 1. you must upgrade CPU to at least a Z80B (rated at 6Mhz but all i have
>> seen will run at 6.5Mhz) or greater of course (i use 8Mhz)
>> 2. Some ROMs in the ZX81's are too slow :-( i have found the motorola
>> type to be useable.
>> 3. if you have a soundcard you need to route the constant 3.25Mhz from
>> the cpu to your sound card (or cut a track on the mainboard)
>>
>> a quick PDF i knocked up here
>>
>> http://www.debraclayton.webspace.virginmedia.com/zxulamk2.pdf
>>
>> regards Andy
>
> Very impressive - its a shame it's not possible to make a ZX81 clone-
> kit using it (ZX11 anyone?!)

Oh it quite possible to build a clone around a CPLD based ULA, i did 
such a thing, used even less passive components that the original, 
properly split the databus and addresss bus, so that got rid of 17 
resistors for a start, tr1 circuit on the cpld, so that anothe few 
components gone.

to say i've only been playing with CPLD's since march i reckon i'm doing 
quite well :-)

Andy

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#560

Am 17.12.2011 13:15, schrieb david:

> Very impressive - its a shame it's not possible to make a ZX81 clone-
> kit using it (ZX11 anyone?!)

Why not? I'm sure it will work in ZX96 and ZX2000 too, because they use 
the Sinclair-ULA.
Did you never hear about ZX96 and ZX2000? You will not have been at one 
of the famous ZX-TEAM-meetings.

Next year, from 23rd until 25th of march 2012 the 16th ZX-TEAM-meeting 
will take place in a very little village called Mahlerts in the heart of 
Germany near the town Fulda.
More information at www.zx81.de.

I'm very sure, you will be able to see AX81: the ZX81 in one ATmega-chip 
at that meeting too.

Peter

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