back to source

Floppy Corrective Comment

corrective comment from Ignacio Menendez, Jan 2022
I just read a very interesting article on the history of microprogramming, at your portal.

One small observation, there’s a statement that IBM first used the diskette loading for the 370/3145 cpu in 1971…

This is incorrect, IBM first used in the 60’s, for diskette loading of microcode, on the 360/2835 Control Unit for the high speed 2305 drum.

These were only attachable via a 360/2880 Channel to the 360/2075 and 360/2091.

The data rate was too fast to use on 2065 and below.

(I know, I worked on these 2835/2305 drums (were actually fixed head disks, I wrote part of the microprogram for the 2835))


From Ed-Thelen Org Come-history

A Brief History of Microprogramming

Page 10, Second paragraph:

“IBM invented the eight-inch floppy diskette and its drive to improve the distribution of microcode patches and diagnostics; the diskette was first used in 1971 on the System/370 Model 145, which had a writable control store (WCS) of up to 16K words of 32 bits each.”