Hello from Nashville, Tennessee USA!
Hello from Nashville, Tennessee USA!
Hi there! I live in the suburbs of Nashville, Tennessee USA. I recently acquired a "used, untested" ZX81 from eBay, along with a Sinclair 16K memory pack, replacing the originals I owned as a teenager in 1981. My original was my first computer - I saw one of the ads Sinclair had posted in US computer magazines, saved up my money for a few months and ordered one by mail. I had that original for about a year and used it to learn BASIC and dip my toe into the early days of home computing. I ended up selling that original machine to a friend to purchase my next machine (an Atari 400). That machine in turn led me into the world of Atari computers and I never looked back. Until recently, that is. Over the last year I was getting the urge to replace that original Zeddie from four decades ago, so a few weeks ago I did.
Fortunately, I am an experienced amateur electronics modder and tech, with plenty of tools and the skills to use them, so "untested" doesn't hold much fear for me. As it turns out, the machine had been opened by a prior owner, which ruined the original keyboard membrane connector. After confirming the computer would power on to the expected "K" cursor, I have since cleared out the shredded debris from the edge connectors on the PCB, then removed the original RF modulator board and built a composite mod circuit on perfboard using instructions found here in the forums. A replacement keyboard has arrived now from the UK just yesterday, and I have a vLA81 en route to me from New Zealand as I write.
Today, I received a new CMOS-based Z84 to replace the NEC original, along with some 32K SRAMs. The new CPU is already in the machine, and one of the SRAM's will be used first as a basic 16K internal upgrade, then as a 32K upgrade once the vLA81 arrives. I also have new 3.5mm phono connectors coming to replace the badly worn and damaged originals. I also plan to replace the original 7805 with a modern switching replacement but I don't yet have one ordered. I meant to do that last week when I ordered the new Z84 and SRAMs but forgot.
My younger daughter is an artist and she will hand-paint the original embossed lettering on the case of the ZX81 as well as the RAM pack, even though I don't intend to ever use that except as a memento. After I get the little machine put back together, I look forward to exploring some of the software I never saw as a kid, and reliving some of those early experiences of laboriously typing in BASIC programs and the joy when they actually worked.
Anyway, that is my story and thank you for reading.
Fortunately, I am an experienced amateur electronics modder and tech, with plenty of tools and the skills to use them, so "untested" doesn't hold much fear for me. As it turns out, the machine had been opened by a prior owner, which ruined the original keyboard membrane connector. After confirming the computer would power on to the expected "K" cursor, I have since cleared out the shredded debris from the edge connectors on the PCB, then removed the original RF modulator board and built a composite mod circuit on perfboard using instructions found here in the forums. A replacement keyboard has arrived now from the UK just yesterday, and I have a vLA81 en route to me from New Zealand as I write.
Today, I received a new CMOS-based Z84 to replace the NEC original, along with some 32K SRAMs. The new CPU is already in the machine, and one of the SRAM's will be used first as a basic 16K internal upgrade, then as a 32K upgrade once the vLA81 arrives. I also have new 3.5mm phono connectors coming to replace the badly worn and damaged originals. I also plan to replace the original 7805 with a modern switching replacement but I don't yet have one ordered. I meant to do that last week when I ordered the new Z84 and SRAMs but forgot.
My younger daughter is an artist and she will hand-paint the original embossed lettering on the case of the ZX81 as well as the RAM pack, even though I don't intend to ever use that except as a memento. After I get the little machine put back together, I look forward to exploring some of the software I never saw as a kid, and reliving some of those early experiences of laboriously typing in BASIC programs and the joy when they actually worked.
Anyway, that is my story and thank you for reading.
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- Posts: 2191
- Joined: Sat Nov 26, 2016 2:42 am
Re: Hello from Nashville, Tennessee USA!
Welcome on board and back to the world of zeddy! Wish I had someone to paint in logos for me.
If you haven’t already spotted them you can get TZXDuinos and MAXDuinos for software loading. Much better than trying with tapes.
If you haven’t already spotted them you can get TZXDuinos and MAXDuinos for software loading. Much better than trying with tapes.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Hello from Nashville, Tennessee USA!
Hi Dr V.
A big welcome from me also.
I never ceased to be amazed at the reach this peculiarly little computer had. We have forum members from just about most places on the planet, in Europe there is a very active German forum as well as Denmark ,the Netherlands and France just to name a few. On your side of the puddle we have members from New York to Texas too.
Lots to read and digest here and any questions are sure to get a positive response so again welcome to our world.
Regards.
Moggy.
A big welcome from me also.
I never ceased to be amazed at the reach this peculiarly little computer had. We have forum members from just about most places on the planet, in Europe there is a very active German forum as well as Denmark ,the Netherlands and France just to name a few. On your side of the puddle we have members from New York to Texas too.
Lots to read and digest here and any questions are sure to get a positive response so again welcome to our world.
Regards.
Moggy.
Re: Hello from Nashville, Tennessee USA!
Hi DrV,
Welcome and congrats on getting your ZX81 working
You'll find a lot of useful info on my website:
https://www.timexsinclair.com/
In particular, look under the Type-in Program tab of this page:
https://www.timexsinclair.com/computers ... /articles/
(it can take a second to load b/c there are 1819 articles.)
And, since you're in Nashville, you might enjoy this blog post: https://www.timexsinclair.com/blog/jim- ... terprises/
Best,
David
Welcome and congrats on getting your ZX81 working
You'll find a lot of useful info on my website:
https://www.timexsinclair.com/
In particular, look under the Type-in Program tab of this page:
https://www.timexsinclair.com/computers ... /articles/
(it can take a second to load b/c there are 1819 articles.)
And, since you're in Nashville, you might enjoy this blog post: https://www.timexsinclair.com/blog/jim- ... terprises/
Best,
David
My archive.org collection, containing many Timex/Sinclair related publications.
TimexSinclair.com, my website about Sinclair computers in the US.
TimexSinclair.com, my website about Sinclair computers in the US.
Re: Hello from Nashville, Tennessee USA!
Thanks for those links - "Weird Nashville," indeed. Every city and town has its lesser-known stories and tales and that was a pretty good one. Thanks for sharing!jdfan1000 wrote: ↑Thu Jul 08, 2021 5:51 pm Hi DrV,
Welcome and congrats on getting your ZX81 working
You'll find a lot of useful info on my website:
https://www.timexsinclair.com/
In particular, look under the Type-in Program tab of this page:
https://www.timexsinclair.com/computers ... /articles/
(it can take a second to load b/c there are 1819 articles.)
And, since you're in Nashville, you might enjoy this blog post: https://www.timexsinclair.com/blog/jim- ... terprises/
Best,
David
And thanks to all for warm welcome - there's a tremendous depth of knowledge gathered on these little machines, and I am four decades out of date on all of it!
Re: Hello from Nashville, Tennessee USA!
hello and welcome…
With that name game 60 in 1K hires must be played.
A preview in this video (from 4:10) https://www.youtube.com/watch?v=HXMWNzL ... 8&index=21
With that name game 60 in 1K hires must be played.
A preview in this video (from 4:10) https://www.youtube.com/watch?v=HXMWNzL ... 8&index=21
Re: Hello from Nashville, Tennessee USA!
The State of the Zeddy today:
So far, composite mod fabricated based on a schematic found here in the forums somewhere (3 resistors, 1 transistor, couple of capacitors); original NEC-made Z80 replaced with a modern Zilog CMOS-based Z84; original Ferranti ULA replaced with a vLA81; and most recently, SRAM chips removed and 28-pin socket installed with "easy" 16K mod (LK2 connected, pins 1, 21 and 23 wired to diodes D1, D3 and D5). I have new 3.5 mono phono jacks on hand to install next and then it will be time to work on the case repainting, replace the keyboard with a new one (also on hand already) and then maybe replace the 7805 with a modern switching unit. But the machine is already drawing so little power with the new CMOS chips it's hardly worth it.
So far, composite mod fabricated based on a schematic found here in the forums somewhere (3 resistors, 1 transistor, couple of capacitors); original NEC-made Z80 replaced with a modern Zilog CMOS-based Z84; original Ferranti ULA replaced with a vLA81; and most recently, SRAM chips removed and 28-pin socket installed with "easy" 16K mod (LK2 connected, pins 1, 21 and 23 wired to diodes D1, D3 and D5). I have new 3.5 mono phono jacks on hand to install next and then it will be time to work on the case repainting, replace the keyboard with a new one (also on hand already) and then maybe replace the 7805 with a modern switching unit. But the machine is already drawing so little power with the new CMOS chips it's hardly worth it.
Re: Hello from Nashville, Tennessee USA!
With the VLA81 inside you should have 32k already!
In theory, there is no difference between theory and practice. But, in practice, there is.
Re: Hello from Nashville, Tennessee USA!
No it doesn't. But 16k RAM chips are very uncommon. Most SRAM chips with 28 Pins are at least 32K. And vLA81 can modify the ROMCS and RAMCS behaviour so that 32k can be accessed.
In theory, there is no difference between theory and practice. But, in practice, there is.