TT Rom access speedup
Posted: Wed Mar 06, 2019 2:42 pm
Hello,
So far I've tried this sucessfully on 3 different TT machines and it works well.
It only takes two diodes, Germanium or Schottky (Bat 48).
Connect the anode of one diode to XDS0 and a second diode to XDS1.
These signals can be found on the ST-Ram board pins 15 and 16 of the C row, connector to the front of the TT.
Next, connect both cathodes together and wire these to the CS of an Eprom. (Just any Eprom will do, it's pin 20)
The boards I tested had either Eproms with 120nS, 150nS or Flash (placed by me) with 90nS access time.
Slower Eproms most likely will not do.
The result is much faster Eprom access.
Gembench shows increase of speed, but not a real value. (On average 20 to 30% depending on the base of comparison and GB version)
Windows will pop-up much faster and boot time will decrease.
It is possible to connect a switch in the cable to the CS of the Eproms, to go back to "normal" speed.
This hardware has about the same speed increase as a copy of the OS to fastram will give.
Advantages are no Ram usage and very small cost. Switching is also very easy.
BR/
Guus
So far I've tried this sucessfully on 3 different TT machines and it works well.
It only takes two diodes, Germanium or Schottky (Bat 48).
Connect the anode of one diode to XDS0 and a second diode to XDS1.
These signals can be found on the ST-Ram board pins 15 and 16 of the C row, connector to the front of the TT.
Next, connect both cathodes together and wire these to the CS of an Eprom. (Just any Eprom will do, it's pin 20)
The boards I tested had either Eproms with 120nS, 150nS or Flash (placed by me) with 90nS access time.
Slower Eproms most likely will not do.
The result is much faster Eprom access.
Gembench shows increase of speed, but not a real value. (On average 20 to 30% depending on the base of comparison and GB version)
Windows will pop-up much faster and boot time will decrease.
It is possible to connect a switch in the cable to the CS of the Eproms, to go back to "normal" speed.
This hardware has about the same speed increase as a copy of the OS to fastram will give.
Advantages are no Ram usage and very small cost. Switching is also very easy.
BR/
Guus