Tandy 1000 ex/hx PLUS Expansion to 8-Bit ISA Riser card project

[djos]

Huzzah! My 1000 EX finally arrived and in fair condition, the keys need some retr0bright and the the case needs a clean which I knew, but the power cord has some damage at the plug and needs replacing.



If any US residents are visiting their local Home Despot this week, could they please grab a 3-pin mains plug for me? I'm more than happy to pay for USPS shipping, the cost of the plug and some extra coin for a 6-pack of beer? 

[djos]

I managed to find a couple of fairly decent looking US NEMA 515 plugs in white online - this will allow me to get the old girl up and running again safely. 

http://www.leviton.com/en/products/3w101-wh



This morning before work I managed to pop the lid off and check out the 2 expansion cards - much to my delight, the memory expansion is fully populated so the machine has a full 640kb ram. The second card is a Tandy 1200 baud internal modem which will be replaced by a dual serial ISA card to drive a serial mouse.

[djos]

I got some this morning (before work) to test the physical aspects of my design (old one below).



I printed out the design and a few revisions as I found that it needed significant realignment of the header compared to the ISA Slot - the new version has the ISA slot pins offset by only about 2.3mm to the right as opposed to about 7.6mm. the PCB was also way too tall to fit in the top PLUS slot so I've shortened the PCB by quite bit.

Im pretty confident in the design now so I'll add back in the copper pour and I may (or may not) even modify the ISA slot part to remove the screw fixings that my ISA slots dont have.

[djos]

and Done! I just need to order the boards from Elecrow! 



EDIT: Order Placed.

[djos]

Argh, I realised today I've made a monumental stuff up! I followed the wrong diagram in the tech reference manual with for some odd reason shows the pinouts mirrored!  I found the schematics deeper in the tech reference manual diagrams that I believe are correct based on what I'd read previously.

So I've had to re-design the PCB's! I just hope my email to Elecrow gets to them in time to cancel my original design. 

anyhoo, here's the corrected version.

[bitseeker]

At least you're not running a million of them!

[djos]

At least you're not running a million of them!

Too true. 

[djos]

I decided to make use of the time and modified the ISA Slot to remove the mounting points and it makes the board shorter, thus cheaper to make too.





I'll get them made in Blue like the little FDD boards:

[djos]

So I was too slow in realising my mistake and I couldnt cancel my order with Elecrow - nvm, I expected to make some mistakes along the way.  Anyhoo, I've ordered the latest version.   

Amusingly, I may just be able to rescue version 1 of the PCB by installing the right angle header on the "wrong" side of the PCB... I need to test my theory tho... 

PS. I tweaked the design slightly to improve component clearances and add the board version.

[rorysl]

Hey there! Been following this thread with interest. I have a Tandy 1000HX, very similar to the EX, and have been trying to figure out how to add more memory. Plus adapters and the Memory Expansion Card seem to be impossible to source though. If I understand this thread correctly (I'm a bit of a noob) you're designing your own Plus adapter for the Tandy Memory Expansion Card you already have?

If I were to buy or build a Plus card adapter are there any other memory cards that would work with my Tandy? Or do I have to have a Tandy brand one?

Any help or suggestions are greatly appreciated!!

[djos]

Hey there! Been following this thread with interest. I have a Tandy 1000HX, very similar to the EX, and have been trying to figure out how to add more memory. Plus adapters and the Memory Expansion Card seem to be impossible to source though. If I understand this thread correctly (I'm a bit of a noob) you're designing your own Plus adapter for the Tandy Memory Expansion Card you already have?

If I were to buy or build a Plus card adapter are there any other memory cards that would work with my Tandy? Or do I have to have a Tandy brand one?

Any help or suggestions are greatly appreciated!!

G'day, unfortunately Tandy used their own custom DMA /memory controller chip on the EX / HX ram expansion board so cloning it isn't simple. The best thing to do is buy another EX / HX that has it and go from there.

Technically my adapter will work without the ram board but very few expansions will work without the DMA controller.

[rorysl]

Ah! Drag. Ok then. Feel free to send me your Memory Expansion Board then. Lol 

In all seriousness though, thanks for the reply -- the HX/EX is a tough system to find peripherals for and information on!

[djos]

Ah! Drag. Ok then. Feel free to send me your Memory Expansion Board then. Lol 

In all seriousness though, thanks for the reply -- the HX/EX is a tough system to find peripherals for and information on!

Lol, I'd luv to design a new Ram expansion board for the EX/HX machines but im an amature with very very poor understanding of digital logic design.

There's a ton of good info and documentation here including the reference manuals for the EX & HX:

http://www.oldskool.org/guides/tvdog/documents.html

and his FAQ is great too:

http://www.oldskool.org/guides/tvdog/1kfaq.html

[rorysl]

Thanks for the links -- I think I've come across them before in my quest. For now, I'm going to concentrate on upgrading to a NEC V20 and maybe installing a SmartWatch chip and keep scanning eBay for memory expansion cards!

[djos]

Thanks for the links -- I think I've come across them before in my quest. For now, I'm going to concentrate on upgrading to a NEC V20 and maybe installing a SmartWatch chip and keep scanning eBay for memory expansion cards!

Cool, I've a got a couple of V20's lying around too and have also ordered a compatible smart watch chip from Asia. 

[WastelandTek]

lol

the deeper I dig in this forum the more crazy I find

good crazy, mind you

[djos]

lol

the deeper I dig in this forum the more crazy I find

good crazy, mind you

hehe, yeah you do have to be a bit mad to enjoy playing with 20-30 year old computers. 

[bitseeker]

I've got a CoCo 1 from 1981 that's been waiting for diagnosis of screen garbage when powered on. It was my first home computer, so one day I'll get it up and running again. I probably have the cassette tapes for it somewhere. I learned to program on a TI 99/4 (1979), but never got around to acquiring one.

[djos]

I've got a CoCo 1 from 1981 that's been waiting for diagnosis of screen garbage when powered on. It was my first home computer, so one day I'll get it up and running again. I probably have the cassette tapes for it somewhere. I learned to program on a TI 99/4 (1979), but never got around to acquiring one.

Nice! I recall seeing the Coco 2's and 3's in my local Tandy Electronics in the 80's, great little machines for the time!

I learned to code in basic on an Amstrad CPC-6128 in primary school about 2 years before we got our Tandy 1000 EX, but I've never really felt the desire to get one. Prolly due to my distaste for the shockingly expensive 3" floppy disks I had to spend my lawn mowing money on so I could get a copy of my own programs. 

[rorysl]

Cool, I've a got a couple of V20's lying around too and have also ordered a compatible smart watch chip from Asia. 

Awesome -- would you mind sharing the model number or link? I need to order one myself that is EX/HX compatible.

[djos]

Cool, I've a got a couple of V20's lying around too and have also ordered a compatible smart watch chip from Asia. 

Awesome -- would you mind sharing the model number or link? I need to order one myself that is EX/HX compatible.

I found some NEC V20 D70108HCZ-16 units on eBay, as long as they are D70108HCZ-8 or better they'll work fine.

[rorysl]

Great! And the Smartwatch compatible chips were...?

Thanks again for all the help!

[djos]

Great! And the Smartwatch compatible chips were...?

Thanks again for all the help!

These ones

https://www.ebay.com.au/itm/182164983799

[djos]

So my v7 design while it works (electrically if right angle header is mounted on the back side of the board).

V8 is more compact and cheaper to make as the PCB is shorter (there's no need for the mounting holes on either side).

[DavinD]

So, the cable I made doesn't fit into the 1000ex.  It has the right number of pins, but the connector is too wide.  I would need to break the plastic edges off the connector on the expansion board, and I'm not sure I want to do that.