On everybody's favorite auction site I saw a PCjr that was untested and did not come with a power supply, keyboard, or monitor. But it did have two cartridges, an unknown sidecar, and a funny little switch hacked into the front bezel:
I bought it. I love funny little switches ... you never know where they lead to.
A few days later I got a pretty dirty system in the mail. But look what I found while cleaning it up:
That my friends is a very rare PC Enterprises speedup board for the PCjr. You remove the 8088 from it's socket and plug the board into the socket. All of this fits under the diskette drive.
The board comes with a NEC V20 and some logic that allows the machine to run at 9.54Mhz. The board can insert extra wait states for RAM and ROM accesses so that the machine is stable even with the RAM being overclocked by a factor of two. It can even fill in the 16K memory hole caused by the PCjr video circuitry.
Translated into English - that's a 'Turbo Jr'. Almost 2x the speed of the original system.
I love funny little switches. The switch on this system is used to control whether the board fills in the 16KB memory hole to make the system behave more like a PC, or just leaves things as they are so that PCjr software using the better CGA+ video modes still works correctly.
I bought it. I love funny little switches ... you never know where they lead to.
A few days later I got a pretty dirty system in the mail. But look what I found while cleaning it up:
That my friends is a very rare PC Enterprises speedup board for the PCjr. You remove the 8088 from it's socket and plug the board into the socket. All of this fits under the diskette drive.
The board comes with a NEC V20 and some logic that allows the machine to run at 9.54Mhz. The board can insert extra wait states for RAM and ROM accesses so that the machine is stable even with the RAM being overclocked by a factor of two. It can even fill in the 16K memory hole caused by the PCjr video circuitry.
Translated into English - that's a 'Turbo Jr'. Almost 2x the speed of the original system.
I love funny little switches. The switch on this system is used to control whether the board fills in the 16KB memory hole to make the system behave more like a PC, or just leaves things as they are so that PCjr software using the better CGA+ video modes still works correctly.
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