Altair 8800 front panel hex display

[Qbertnix]

Noticed this Altair on ebay has a hex display on the front panel, was that kit that existed or is this someone's diy? It's very neatly done.
https://www.ebay.co.uk/itm/235023012435

 

[mountainking]

Noticed this Altair on ebay has a hex display on the front panel, was that kit that existed or is this someone's diy? It's very neatly done.
https://www.ebay.co.uk/itm/235023012435
:i】View attachment 1257977

Interesting, wish the listing mentioned something about the added display.

 

[Martynv]

Never seen anything like that on an Altair before. Could be quite useful, unlike the switch in one picture that faces sideways

 

[btb]

probably won't help too much, but I noticed this machine when it came up at an estate auction earlier: https://www.proxibid.com/asp/LotDetail.asp?lid=74430864
and from what I gathered from other items there it must have belonged to Ed Sandberg of the 3D-TV pioneer HDI, so it could have been his work.

 

[alank2]

Those digits can decode hex from the 4 signals directly and display the correct hex value. I've seen some of these type boards for a RC2014 before. I think the displays are still out there, but probably hard to find and pricey. I wondered about making a FPGA type project at one point that emulated the logic of the displays, but never got around to it. I'm sure there are some old IC"s that did the same, but these displays are cool because they have the decoding IC built right in!

This might be the RC2014 thing I was thinking about:

Datasheet for the display:

https://www.mouser.com/datasheet/2/588/til311-e4-519224.pdf

They are $30 each at Jameco!

 

[1944GPW]

Those digits can decode hex from the 4 signals directly and display the correct hex value. I've seen some of these type boards for a RC2014 before. I think the displays are still out there, but probably hard to find and pricey. I wondered about making a FPGA type project at one point that emulated the logic of the displays, but never got around to it. I'm sure there are some old IC"s that did the same, but these displays are cool because they have the decoding IC built right in!

The manual including schematic for an S-100 front panel with hex display is at
http://www.s100computers.com/Hardware Folder/Wameco/FPB/FPB.htm
I wonder if it could be useful?

 

[Plasmo]

Interesting. I built a front panel for RC2014 (Z80-based computer) using six 7-segment displays, a CPLD, and PS2 keyboard for address/data entry. I was tired of the toggle-switch data entry and found PS2 keyboard can enter data much faster.

https://groups.google.com/g/rc2014-z80/c/FYOinxhk1Ug/m/adGuXkFrBAAJ

 

[Hugo Holden]

Those Hex displays appear to be the common garden Texas Instruments TIL311, these have been around since the 1970's. They are readily available from a number of sellers, I have a box of them:

QTY 1 TIL311 - 8531 Texas Instruments Hexadecimal Display - TI - Red - Rare | eBay

Find many great new & used options and get the best deals for QTY 1 TIL311 - 8531 Texas Instruments Hexadecimal Display - TI - Red - Rare at the best online prices at eBay! Free shipping for many products!

www.ebay.com

(interestingly Innocor in Canada once made a low power CMOS version of them. I think I bought the remainder of their stock. In the past I made these into a 12/24 hr up down clock with 4000 series cmos IC's pic attached).

There is a modern replacement for them too : Avago / Broadcom HDSP -0962 bright green, or red hexadecimal displays, super quality displays. I used these in the keyboard diagnostic instrument in this article:

https://www.worldphaco.com/uploads/HARDWARE_DIAGNOSTIC_TOOL_FOR_THE_SOL.pdf

I also once made a 16 bit binary to to decimal converter that used the TIL311's, it had a very short latency of 350nS to do the conversion. I made it because binary was messing with my head for a project and I wanted to immediately see the decimal value. It came out as a handy sort of "logic probe" for other problems too, I made it with a manual or external data latch input so it could capture transient binary values. It was quite power hungry with all the TTL IC's and I had to ventilate the housing with a fan

 

[alank2]

Nice work on those units Hugo; they are well done.

 

[Plasmo]

I build TIL311-like display out of individual 0603 LED, mainly because I have a roll of the LED, but also because I was wondering how much work it is to manually align&solder them. Alignment wasn’t too hard, but manual solder still took a while.

builderpages:plasmo:cpldtil [RetroBrew Computers Wiki]

www.retrobrewcomputers.org