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dhe

This old Horizon #4

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I purchased this one from Bud. It almost has no memory.

I was planning on maxing it out when Static Memory Prices had fallen! 😃

 

 

horizon4000.jpg

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38 minutes ago, dhe said:

I purchased this one from Bud. It almost has no memory.

I was planning on maxing it out when Static Memory Prices had fallen! 😃

 

 

horizon4000.jpg

Memory chips for that one shouldn't be a real problem now--and it has the socket for a second 154 already, so you can easily double-stack it if you wanted to go that route with 128K chips (not so relevant if using 512K chips though). . .and a couple of the mods @FALCOR4 and I did to make the 4000B boards super stable could probably be done there too with a little cutting and a few flying wires.

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How many 512K chips would I need to purchase to do a single layer (no double stack)?

Do you have a recommendation of Vendor/Chips?

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2 hours ago, dhe said:

How many 512K chips would I need to purchase to do a single layer (no double stack)?

Do you have a recommendation of Vendor/Chips?

It needs a total of 16 chips (assuming your current two chips are 128K, as I haven't looked closely at the part number on them). I usually use the following Alliance chip, although most any chip that is both fast enough and tolerant of the lower voltage when the card switches to battery will do. The price on these has slowly been going up again (even before the pandemic).

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Right now I have two Hitachi 628512 - I'm guessing all compatible.

I will probably end up ordering 16 Alliance and having the two Hitachi as spares.

 

 

628512.pdf

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If you look at the picture, the battery holders are very nice metal units. They make replacing batteries really easy.

Unfortunately when I moved about 20 years ago, things where kind of chaotic and my ram disks where packed away with batteries, which destroyed the contacts on the holders.

 

Some of my units used the old style radio shack plastic battery holders with solder lugs. This 4000 I liked - so I've done some googling.

 

The nice metal style are made by Keystone. AAA part numbers are 137, AA part number is 139. Note, these don't come cheap - about $4.00 each. But, I plan on holding on to my equipment for another 20 years, so to me,  it's ok for me to pay this for the long haul.

 

I also found automotive tape is used by many a home brewer for attaching battery packs.

 

 

image.thumb.png.dc9134d522a82b3644ef311f4b35a608.png

image.thumb.png.b9ef455220113784cb7381f74f21dc81.png

 

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