Upgrade the Disk II controller with shrouded headers

Apple chose bare headers for the disk connectors on the Disk II controller, which make it notoriously easy to connect the drive cable incorrectly.

Jameco's "Shrouded Box Header 20 Pin 2316R-20G" makes an ideal replacement.


The chaotic shambles of EPROM voltages, from 2708 through 2764

Early EPROMs required an unruly assortment of positive and negative power supplies, variously different programming voltages, an assortment of programming voltages.  And they adopted inconsistent part numbering schemes to distinguish these features.

Most surprisingly -- and irritatingly -- manufacturers gradually switched to elevated power supply voltages during programming.  So a 1977 Intel 2716 can be programmed with VCC=5 volts, whereas a 1988 AMD 2716 requires VCC=6 volts during programming.  And Texas Instruments's horribly-complicated TM2716 requires VCC=12 volts during programming!


Rich Mansueto on the Cassie Keyboard

Nov. 4, 2022

Hi Tom,

It's been a pleasure talking to you about the cassie keyboard. It was a fun project. I was a mechanical engineer at Apple from 82-87. The initial design goal was to create a fully encoded keyboard with full size spacing (.75) between keys and only as big as the keys with no perimeter. This was a challenge for several reasons but the biggest was where to put the processors. My initial thoughts were under the space bar since that was the only place possible. Surface mount technology was new, and we didn’t have experience in it, so we built a prototype smt line in our lab to learn how to do it. We also were developing a new bus system for connecting the keyboard, mouse and any other devices in a daisy chain fashion. Mike Clark, who you spoke to, was doing that.

Next thing was to make a modular keyboard for ease of assembly. I came up with the idea of a curved base, so we didn’t have to have sculptured keycaps, but I was trying to have the switches be integral and not use individual switches like we used on our other keyboards. I came up with a switch design that used a molded post on the base with a nylon sleeve to provide a smooth bearing surface and the tactile feel. The base plate had all the switch posts perpendicular to the radius, which made a quite unique and difficult tool to make. The company that made the tool won an award for it because it was so unique and almost impossible to do.

The bearings were heat staked on the base plate. The pcb had the processors and switch contacts on it, and we actually printed carbon pads on the pcb for the contacts. The pcb was put in the base plate, then a sheet of copper spiral springs was installed and then a metal plate to add some weight and then it was screwed together. After assembled the keycaps were installed and then we had a proprietary process for printing the characters on the entire keyboard.

Another interesting thing we did was that we used a 4 conductor 1/8” jack for connecting the cable. The feet on the keyboard housed the female connector and the male end actually formed the other half of the foot.

It was a very radical design from what was on the market and after we developed it and had it operational we were told it might be perceived as too small for consumers, even though it was a full size keyboard!

I would be happy to answer any other questions you may have and feel free to share this. Thanks for being interested in my work.

Rich Mansueto


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