MOS 6581 “SID” chip is the audible output of a Commodore 64 computer. It was revolutionary when it was released in the 1980s, and made it’s way in synthesizers and gave its sound to the Commodore 64.
This chip has an analog nature, filtering, and could produce 3 simultaneous voices – much better than anything IBM’s “personnal computer” could produce at the time.
When we built the 250466 reproduction board, the SID was borrowed from another C64. That meant one of the two Commodore had no audio output. It meant silent gaming and no music.
When it comes to keyboards, the best-designed touch-typist keyboard ever made happens to be the IBM Model M.
Well, in theory, it is debatable: some stating the IBM Model F was better. It did come first. But seing how the Model M was meant to replace the Model F [in a more affordable way] and ended up being much more popular, likely because of its form factor that defined the standard PC keyboard layout or the fact it is indestructible.
The model M is the keyboard that defined keyboard layouts. Odds are, the keyboard on your computer uses this same layout.
The model M layout was standardized by ISO in 1994 and ANSI in 1998, with minor additions—most notably the windows and Menu keys.
It is OK to say the model M was the summum keyboard to get.
In any case, they both were utilising the same hardware key switch, which is what optimised the hear-and-feel that made both keyboards so great to use.
Buckling?
The IBM model M was introduced in 1985 and uses a buckling spring type of keyswitch. It is not purely a mechanical keyboard but isn’t either a purely membrane keyboard. The audible buckling spring makes for a great typing feeling and good auditory feedback.
BucklingIBM keyboard buckling springsFully pressed key with spring buckledPressing the key bends the spring. When it does, an audible depression is heard as the feet holding the spring enters contact with the membrane causing the key to be sensed by the computer.
Aditionally, those keyboards are sturdy – a metal frame protects the keyswitch. They are built like tanks and weights in at about 5 lbs (2.25kg) so even after nearly 40 years, they are generally in excellent shape.
The underneat metal plate is curved and give each row of the Model M its correct angle
The keycaps are 2-parts, meaning the actual key that is used to buckle the spring is one thing, but the cap is changeable too. That made useful for commercial point of sales, and jokes in college. But also flexible for custom keyboards.
Model M 2-pieces keycap – F1Model M 2-pieces keycap – ESC
Also, they do not yellow with age. They may have scuffs or marks, but even after 40 years they aren’t yellow.
Difference between mechanical switch and buckling spring
Model F and M are -not- mechanical keyboards.
It isn’t a mechanical switch, but a buckling spring. The contacts on a buckling springs are at the foot of the spring which keeps the key in its upward,position. When pushed down, the spring bends [buckles] and the feet enter contact with the bottom PCB to tell the computer a key is pressed.
For a mechanical key switch, the contacts are released by the movement of the spring-loaded plunger. There is a great article on Popular Mechanics about the differences, where they talk about replica Model F keyboards.
Difference in movement Buckling Spring and Cherry MX blue mechanical switch
To many, the mechanical keyswitch are just a way to recreate something similar to the optimal comfort of a buckling spring.
While buckling springs make for an awesome feel, the spring needs to be fully extended to reset, so from pressed to unpressed is a slower process than with mechanical keyswitch, which in turn makes for poor gameplay. The matrix nature of the controller also allows ghosting wich doesn’t help gamers either.
Model M compared to modern fullsize keyboard
Model Ms are excellent programmer keyboards.
So why aren’t more people using them?
Being created in early 1980s, they were meant for AT keyboard connection, and evolved to PS/2 keyboard DIN, both of which are not hot-swappable, and rarely installed on modern laptop computers.
AT and PS/2 keyboard connections – image courtesy of PC Mag (no affiliation)
Today we explore alternate controllers for the IBM Model M keyboard that will enable the keyboard to be compatible with modern-day USB.
A while ago we talked about the upcoming project of a replacement CIA chip for the C-64 and it pointed to a YouTube video that showed an overexcited Perifractic demonstrating an upcoming J-CIA that would in theory be a drop-in replacement for any failing CIA chip.
Well, the C-64 variant has been available since this month and we purchased a pair to try out.
We are All Geeks! 