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ISA RAM card, my easter project

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First post, by Jo22

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Hello everyone,

I'm currently attempting to build a 128KiB UMB card for my PC/XT,
using the schematics I've found at the Vintage Computer Federation Forums.

And while I'm writing these words to you,
I'm listening to this song..

Will I succeed ? - I have no idea, but I have hope and confidence.

So stay tuned. 😀
- I'll report my progress at random times in this thread..

Best regards and
happy easter my friends,
Jo22

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 1 of 66, by Jo22

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First step..

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 2 of 66, by Jo22

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Second. Wires..

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 3 of 66, by Jo22

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And here's the schematic I'm using.. 😀

umb4xt.png
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>> Special thanks to Ruud! <<

Source: http://www.Baltissen.org

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 4 of 66, by Jo22

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Third. More wires! 😁

As you may noticed, I'm using two 74LS08N instead of just one (quad dual-input&gate).
Sounds like a waste, doesn't it ? Well, I like things to be discrete as possible. Hope it works that way.
If I encounter trouble, maybe I should ground the unused inputs ? Any suggestions welcome. 😀

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 5 of 66, by Jo22

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Fourth. Things are gettin' hairy.. 😉

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 6 of 66, by keropi

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Nice progress there, keep us posted with more pics 😀

🎵 🎧 PCMIDI MPU , OrpheusII , Action Rewind , Megacard and 🎶GoldLib soundcard website

Reply 7 of 66, by Jo22

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Thanks keropi, I'll do! I've just completed the basic wiring. 😀
I.e., the connections between the logic chip are established.
It's just the wiring for the 128KiB SRAM that still has to be done.

If nothing goes wrong (crosstalk ? What`s that ?), I should be able to test the card
within a few days, as soon as the TTL chips arrived. I ordered them online,
because my local electronics shop doesn't have them.

Like usual. They now have Arduino and RPi accessories among the basic parts
(resistors, caps, switches, etc), but sorted out (or rather did not reorder) some classic
stuff like radio-related components (PL and DIN connectors), Germanium transitors,
and some of the lesser common TTL parts.

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 8 of 66, by Jo22

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Quick update. Two types of ICs are on the way. The SRAM won't arrive until next week, though.

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 9 of 66, by Jo22

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Quick update. One of the 74LS08N arrived today. 😀

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 10 of 66, by ibmapc

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This looks great!
Have you had a look at this? http://www.vcfed.org/forum/showthread.php?281 … quivillent-PROM
This is a very nice write up about the same project http://www.vcfed.org/forum/showthread.php?626 … d-Portable-5155

This provides UMB in the same regions as your project. The advantage for your project is that it should work on clones as well as the IBM 5160.

As always, I'll provide a programmed GAL to anyone interested in trying this mod for the cost of shipping!!

Greg

Reply 12 of 66, by Jo22

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ibmapc wrote:
This looks great! Have you had a look at this? http://www.vcfed.org/forum/showthread.php?281 … quivillent-PROM This is a very […]
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This looks great!
Have you had a look at this? http://www.vcfed.org/forum/showthread.php?281 … quivillent-PROM
This is a very nice write up about the same project http://www.vcfed.org/forum/showthread.php?626 … d-Portable-5155

This provides UMB in the same regions as your project. The advantage for your project is that it should work on clones as well as the IBM 5160.

As always, I'll provide a programmed GAL to anyone interested in trying this mod for the cost of shipping!!

Greg

Thank your very much, Greg! I spent this night reading it and it was very interesting and informative. Thanks, again, Greg. 😀
The computer I'm hoping to get it going to in is an old Nixdorf 8810 M35. I'll do tests on a separate system first, of course.
As often with such classics, care has to be taken of to not damaging them.

luckybob wrote:

I'm curious. Why? premade cards are very common. I'm assuming this is intentionally a pet project?

Thanks for your interest, luckybob! 😀 Yes, it is a pet project for one.
Though I also find it less stressing at the moment to build such a behemoth using classic DIP/DIL chips than
getting hold of certain SMD parts in correct size and shape. As you can see, I've got an 1MB card from Lo-Tec/TexElec..

Unfortunately, I haven't gotten yet exactly the SMD chips required for it on usual places like eBay, Amazon or locally
(This may sound odd, but in terms of tinkering,I was raised the oldschool way by my father. We often went to our favorite
electronics store by tram or car and talked to Peter, that friendly dude behind the counter, about our electronics projects.
Akin to some folks would have done in the 60s/70s when they went to their accustomed radio store).

To make sure I get the right parts, especially in the right size, I would have to order them from Mouser
or Farnell using the parts numbers mentioned in the Lo-Tec Wiki, both of which I have no account for yet.
(I ordered the PCB from over sea, so it is too expensive to ruin by trial&error.)

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 13 of 66, by ibmapc

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Jo22 wrote:

...The computer I'm hoping to get it going to in is an old Nixdorf 8810 M35. ...

When I saw PC/XT in your original post I assumed IBM 5160.

Jo22 wrote:

...To make sure I get the right parts, especially in the right size, I would have to order them from Mouser
or Farnell using the parts numbers mentioned in the Lo-Tec Wiki, both of which I have no account for yet...

I've ordered plenty from Mouser without an account. Just check out as a guest. For me, the soldering of the SMD parts would be most challenging. I've done it, but I always struggle correcting Solder bridges.

Reply 14 of 66, by Jo22

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ibmapc wrote:

When I saw PC/XT in your original post I assumed IBM 5160.

Ah, I see, sorry about that. 😅 I meant to say PC/XT compatibe.. Though, now that I'm thinking about it,
that would also have been a a bit of a misnomer. 😐 The link said it was AT compatible somehow, what ever that means.. 😕
Let's say it's an 8088 PC with 8-Bit slots (no V20 upgrade yet, since that didn't work last time. The M35 BIOS was smarter than good for it.)

ibmapc wrote:

I've ordered plenty from Mouser without an account. Just check out as a guest.

Thank you for the tip! 😀 I never knew of those big companies until I visited the Lo-Tech website.
In the past, when I had to order parts from an electronics company, I usually had a look at Conrad Electronics, Pollin Electronic or Reichelt Elektronik.

ibmapc wrote:

For me, the soldering of the SMD parts would be most challenging. I've done it, but I always struggle correcting Solder bridges.

Me, too. 😅 IMHO it's quite finicky. My soldering iron isn't exactly made for this, either. It works, but it requires a tranquil hand.
Last time, when I installed some serial conversion chips for another project (dedicated MOD4WIN player based on an old x86 set-top box),
I had to hold my breath and be completely relaxed (to keep my heart beat low) during the soldering process. When I finished it, I felt quite dizzy.

Edit: I'm curious, what kind of SMD soldering projects are you interested in (for example) ?

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 15 of 66, by ibmapc

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ibmapc wrote:

For me, the soldering of the SMD parts would be most challenging. I've done it, but I always struggle correcting Solder bridges.

Jo22 wrote:
Me, too. :sweatdrop: IMHO it's quite finicky. My soldering iron isn't exactly made for this, either. It works, but it requires […]
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Me, too. 😅 IMHO it's quite finicky. My soldering iron isn't exactly made for this, either. It works, but it requires a tranquil hand.

Last time, when I installed some serial conversion chips for another project (dedicated MOD4WIN player based on an old x86 set-top box),
I had to hold my breath and be completely relaxed (to keep my heart beat low) during the soldering process. When I finished it, I felt quite dizzy.

Edit: I'm curious, what kind of SMD soldering projects are you interested in (for example) ?

I have to cut back on my coffee intake for a few days and be well rested, preferably with the kids out of the house before I can tackle SMD work. Lots of good light and magnification helps to. Also, I recently bought a cheap copy of a Hakko Solder station with many different tips that makes things easier to control.

The first SMD stuff I did was making mods to a NetPliance IOpener motherboard to put a faster processor on it. Lately, I've been building and selling Retro-Canada's MDA/CGA/EGA to VGA Converters that use a high speed SRAM chip that is only available in SMD.

Reply 16 of 66, by Jo22

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ibmapc wrote:

I have to cut back on my coffee intake for a few days and be well rested, preferably with the kids out of the
house before I can tackle SMD work.

I see. Good luck! 😀

ibmapc wrote:

Lots of good light and magnification helps to.

Indeed, I fully agree. it's quite handy to have one of these magnifier/lamp combos, too.
A few years ago, I bought one of them (a semi-profrssional model) but ran out of space.

And since it uses a real lamp (no LED) with a nice, warm, white light, I've never dared to set it up.
I'm too afraid it could somehow fall off my working space and break. 😅

ibmapc wrote:

Also, I recently bought a cheap copy of a Hakko Solder station with many different tips that makes things easier to control.

Cool. 😎 Just had a look at hakko.com and saw several SMD capable models, too.
I guess it's a replica of one of the multi-stations, I suppose.

ibmapc wrote:

The first SMD stuff I did was making mods to a NetPliance IOpener motherboard to put a faster processor on it.
Lately, I've been building and selling Retro-Canada's MDA/CGA/EGA to VGA Converters that use a high speed SRAM chip that is only available in SMD.

Just had a look at the Converter and the SRAM (also read the wiki about the IOpener; wonder why they did prevent hacking so much).
- Boy, it's quite some work to solder 44 little feets, yet alone doing that for a serial production (even a small one). 😳

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 17 of 66, by Jo22

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Update. Some more ICs arrived. With Peanuts stamps! 😁

Edit: I forgot to mention..: It was a pair of 74LS138N.

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 18 of 66, by Jo22

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Today is Second Sunday of Easter (aka Little Easter).. I wished I could show you any progress.
Unfortunately, I still have to wait for the SRAM to arrive.

So since I mentioned these stamps of Snoopy and The Peanuts gang,
how about going a bit off-topic and look at at some of my stamps instead ? 😉

PS: Listening to this AY-3-8910 OST right now.

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 19 of 66, by Jo22

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Update. Another 74LS08N arrived today.

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//