Today we’ll be taking a look at a Generic 8 Port USB/PS2 KVM Switch which has 8 ports which you can switch to with 2x USB/PS2 inputs and a monitor output. There are no markings on the vendor on the outside of the box.
After a few screws we’re in.
(Picture might look a little distorted due to Pano stitching)
Once inside, we can see the PCB doesn’t use up all of the space available. They are using one chip 8 times (as you might expect), have a little bit of logic (2x 74HC13 and 2x 74HC14), there’s a main chip and a chip for each USB port. There is a 6x 2 pin header for the main chip, the front panel buttons/LEDs connects via a 34 pin connector and there is another 34 pin connector spare with some unpopulated components nearby, wonder what other functionality they could have added. PCB date is 30th week, 2004.
The input voltage to the KVM is 9V so we have an ST L7805 bringing it down to 5V with a decent pad for heat dissipation plus an AMS1117 LDO.
Under the A3 label we have the main chip, an Atmel ATmega64 which can run up to 16MHz with 64KB flash, 4KB SRAM, 2KB EEPROM to name a few features. It looks like the PS2 riser board connects to this chip. Running with a 16MHz crystal.
For each port, we have a Cypress CY7C63723C USB and PS/2 Controller/MCU which can auto configure itself to act as a USB or PS/2. It can run at 12MHz, has 256B of RAM and 8KB of EPROM for programming, 16 GPIOs with an SPI interface.
For the switching side of things, we have 6x IDT QS3251Q 8:1 multiplexer/demultiplexer, this would be used for the VGA switching side.
For the 2x USB input ports, we have a Cypress SL811HST USB Host/Slave Controller which supports full speed 12Mbps and low speed 1.5Mbps USB. Running with a 12MHz crystal.
And that’s all.
